| CVE |
Vendors |
Products |
Updated |
CVSS v3.1 |
| A race condition in Grafana Live allows authenticated users with Viewer role to trigger a server crash by sending concurrent requests that cause a fatal map access error. This results in complete service unavailability requiring restart of the Grafana server. |
| In the Linux kernel, the following vulnerability has been resolved:
RDMA/hns: Fix unlocked call to hns_roce_qp_remove()
Sashiko points out that hns_roce_qp_remove() requires the caller to hold
locks. The error flow in hns_roce_create_qp_common() doesn't hold those
locks for the error unwind so it risks corrupting memory.
Grab the same locks the other two callers use. |
| In the Linux kernel, the following vulnerability has been resolved:
nfc: llcp: add missing return after LLCP_CLOSED checks
In nfc_llcp_recv_hdlc() and nfc_llcp_recv_disc(), when the socket
state is LLCP_CLOSED, the code correctly calls release_sock() and
nfc_llcp_sock_put() but fails to return. Execution falls through to
the remainder of the function, which calls release_sock() and
nfc_llcp_sock_put() again. This results in a double release_sock()
and a refcount underflow via double nfc_llcp_sock_put(), leading to
a use-after-free.
Add the missing return statements after the LLCP_CLOSED branches
in both functions to prevent the fall-through. |
| In the Linux kernel, the following vulnerability has been resolved:
ocfs2: fix possible deadlock between unlink and dio_end_io_write
ocfs2_unlink takes orphan dir inode_lock first and then ip_alloc_sem,
while in ocfs2_dio_end_io_write, it acquires these locks in reverse order.
This creates an ABBA lock ordering violation on lock classes
ocfs2_sysfile_lock_key[ORPHAN_DIR_SYSTEM_INODE] and
ocfs2_file_ip_alloc_sem_key.
Lock Chain #0 (orphan dir inode_lock -> ip_alloc_sem):
ocfs2_unlink
ocfs2_prepare_orphan_dir
ocfs2_lookup_lock_orphan_dir
inode_lock(orphan_dir_inode) <- lock A
__ocfs2_prepare_orphan_dir
ocfs2_prepare_dir_for_insert
ocfs2_extend_dir
ocfs2_expand_inline_dir
down_write(&oi->ip_alloc_sem) <- Lock B
Lock Chain #1 (ip_alloc_sem -> orphan dir inode_lock):
ocfs2_dio_end_io_write
down_write(&oi->ip_alloc_sem) <- Lock B
ocfs2_del_inode_from_orphan()
inode_lock(orphan_dir_inode) <- Lock A
Deadlock Scenario:
CPU0 (unlink) CPU1 (dio_end_io_write)
------ ------
inode_lock(orphan_dir_inode)
down_write(ip_alloc_sem)
down_write(ip_alloc_sem)
inode_lock(orphan_dir_inode)
Since ip_alloc_sem is to protect allocation changes, which is unrelated
with operations in ocfs2_del_inode_from_orphan. So move
ocfs2_del_inode_from_orphan out of ip_alloc_sem to fix the deadlock. |
| In the Linux kernel, the following vulnerability has been resolved:
btrfs: do not strictly require dirty metadata threshold for metadata writepages
[BUG]
There is an internal report that over 1000 processes are
waiting at the io_schedule_timeout() of balance_dirty_pages(), causing
a system hang and trigger a kernel coredump.
The kernel is v6.4 kernel based, but the root problem still applies to
any upstream kernel before v6.18.
[CAUSE]
From Jan Kara for his wisdom on the dirty page balance behavior first.
This cgroup dirty limit was what was actually playing the role here
because the cgroup had only a small amount of memory and so the dirty
limit for it was something like 16MB.
Dirty throttling is responsible for enforcing that nobody can dirty
(significantly) more dirty memory than there's dirty limit. Thus when
a task is dirtying pages it periodically enters into balance_dirty_pages()
and we let it sleep there to slow down the dirtying.
When the system is over dirty limit already (either globally or within
a cgroup of the running task), we will not let the task exit from
balance_dirty_pages() until the number of dirty pages drops below the
limit.
So in this particular case, as I already mentioned, there was a cgroup
with relatively small amount of memory and as a result with dirty limit
set at 16MB. A task from that cgroup has dirtied about 28MB worth of
pages in btrfs btree inode and these were practically the only dirty
pages in that cgroup.
So that means the only way to reduce the dirty pages of that cgroup is
to writeback the dirty pages of btrfs btree inode, and only after that
those processes can exit balance_dirty_pages().
Now back to the btrfs part, btree_writepages() is responsible for
writing back dirty btree inode pages.
The problem here is, there is a btrfs internal threshold that if the
btree inode's dirty bytes are below the 32M threshold, it will not
do any writeback.
This behavior is to batch as much metadata as possible so we won't write
back those tree blocks and then later re-COW them again for another
modification.
This internal 32MiB is higher than the existing dirty page size (28MiB),
meaning no writeback will happen, causing a deadlock between btrfs and
cgroup:
- Btrfs doesn't want to write back btree inode until more dirty pages
- Cgroup/MM doesn't want more dirty pages for btrfs btree inode
Thus any process touching that btree inode is put into sleep until
the number of dirty pages is reduced.
Thanks Jan Kara a lot for the analysis of the root cause.
[ENHANCEMENT]
Since kernel commit b55102826d7d ("btrfs: set AS_KERNEL_FILE on the
btree_inode"), btrfs btree inode pages will only be charged to the root
cgroup which should have a much larger limit than btrfs' 32MiB
threshold.
So it should not affect newer kernels.
But for all current LTS kernels, they are all affected by this problem,
and backporting the whole AS_KERNEL_FILE may not be a good idea.
Even for newer kernels I still think it's a good idea to get
rid of the internal threshold at btree_writepages(), since for most cases
cgroup/MM has a better view of full system memory usage than btrfs' fixed
threshold.
For internal callers using btrfs_btree_balance_dirty() since that
function is already doing internal threshold check, we don't need to
bother them.
But for external callers of btree_writepages(), just respect their
requests and write back whatever they want, ignoring the internal
btrfs threshold to avoid such deadlock on btree inode dirty page
balancing. |
| In the Linux kernel, the following vulnerability has been resolved:
btrfs: lock the inode in shared mode before starting fiemap
Currently fiemap does not take the inode's lock (VFS lock), it only locks
a file range in the inode's io tree. This however can lead to a deadlock
if we have a concurrent fsync on the file and fiemap code triggers a fault
when accessing the user space buffer with fiemap_fill_next_extent(). The
deadlock happens on the inode's i_mmap_lock semaphore, which is taken both
by fsync and btrfs_page_mkwrite(). This deadlock was recently reported by
syzbot and triggers a trace like the following:
task:syz-executor361 state:D stack:20264 pid:5668 ppid:5119 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5293 [inline]
__schedule+0x995/0xe20 kernel/sched/core.c:6606
schedule+0xcb/0x190 kernel/sched/core.c:6682
wait_on_state fs/btrfs/extent-io-tree.c:707 [inline]
wait_extent_bit+0x577/0x6f0 fs/btrfs/extent-io-tree.c:751
lock_extent+0x1c2/0x280 fs/btrfs/extent-io-tree.c:1742
find_lock_delalloc_range+0x4e6/0x9c0 fs/btrfs/extent_io.c:488
writepage_delalloc+0x1ef/0x540 fs/btrfs/extent_io.c:1863
__extent_writepage+0x736/0x14e0 fs/btrfs/extent_io.c:2174
extent_write_cache_pages+0x983/0x1220 fs/btrfs/extent_io.c:3091
extent_writepages+0x219/0x540 fs/btrfs/extent_io.c:3211
do_writepages+0x3c3/0x680 mm/page-writeback.c:2581
filemap_fdatawrite_wbc+0x11e/0x170 mm/filemap.c:388
__filemap_fdatawrite_range mm/filemap.c:421 [inline]
filemap_fdatawrite_range+0x175/0x200 mm/filemap.c:439
btrfs_fdatawrite_range fs/btrfs/file.c:3850 [inline]
start_ordered_ops fs/btrfs/file.c:1737 [inline]
btrfs_sync_file+0x4ff/0x1190 fs/btrfs/file.c:1839
generic_write_sync include/linux/fs.h:2885 [inline]
btrfs_do_write_iter+0xcd3/0x1280 fs/btrfs/file.c:1684
call_write_iter include/linux/fs.h:2189 [inline]
new_sync_write fs/read_write.c:491 [inline]
vfs_write+0x7dc/0xc50 fs/read_write.c:584
ksys_write+0x177/0x2a0 fs/read_write.c:637
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f7d4054e9b9
RSP: 002b:00007f7d404fa2f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f7d405d87a0 RCX: 00007f7d4054e9b9
RDX: 0000000000000090 RSI: 0000000020000000 RDI: 0000000000000006
RBP: 00007f7d405a51d0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 61635f65646f6e69
R13: 65646f7475616f6e R14: 7261637369646f6e R15: 00007f7d405d87a8
</TASK>
INFO: task syz-executor361:5697 blocked for more than 145 seconds.
Not tainted 6.2.0-rc3-syzkaller-00376-g7c6984405241 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor361 state:D stack:21216 pid:5697 ppid:5119 flags:0x00004004
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5293 [inline]
__schedule+0x995/0xe20 kernel/sched/core.c:6606
schedule+0xcb/0x190 kernel/sched/core.c:6682
rwsem_down_read_slowpath+0x5f9/0x930 kernel/locking/rwsem.c:1095
__down_read_common+0x54/0x2a0 kernel/locking/rwsem.c:1260
btrfs_page_mkwrite+0x417/0xc80 fs/btrfs/inode.c:8526
do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2947
wp_page_shared+0x15e/0x380 mm/memory.c:3295
handle_pte_fault mm/memory.c:4949 [inline]
__handle_mm_fault mm/memory.c:5073 [inline]
handle_mm_fault+0x1b79/0x26b0 mm/memory.c:5219
do_user_addr_fault+0x69b/0xcb0 arch/x86/mm/fault.c:1428
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x7a/0x110 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:copy_user_short_string+0xd/0x40 arch/x86/lib/copy_user_64.S:233
Code: 74 0a 89 (...)
RSP: 0018:ffffc9000570f330 EFLAGS: 000502
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
tty: n_gsm: fix deadlock and link starvation in outgoing data path
The current implementation queues up new control and user packets as needed
and processes this queue down to the ldisc in the same code path.
That means that the upper and the lower layer are hard coupled in the code.
Due to this deadlocks can happen as seen below while transmitting data,
especially during ldisc congestion. Furthermore, the data channels starve
the control channel on high transmission load on the ldisc.
Introduce an additional control channel data queue to prevent timeouts and
link hangups during ldisc congestion. This is being processed before the
user channel data queue in gsm_data_kick(), i.e. with the highest priority.
Put the queue to ldisc data path into a workqueue and trigger it whenever
new data has been put into the transmission queue. Change
gsm_dlci_data_sweep() accordingly to fill up the transmission queue until
TX_THRESH_HI. This solves the locking issue, keeps latency low and provides
good performance on high data load.
Note that now all packets from a DLCI are removed from the internal queue
if the associated DLCI was closed. This ensures that no data is sent by the
introduced write task to an already closed DLCI.
BUG: spinlock recursion on CPU#0, test_v24_loop/124
lock: serial8250_ports+0x3a8/0x7500, .magic: dead4ead, .owner: test_v24_loop/124, .owner_cpu: 0
CPU: 0 PID: 124 Comm: test_v24_loop Tainted: G O 5.18.0-rc2 #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
Call Trace:
<IRQ>
dump_stack_lvl+0x34/0x44
do_raw_spin_lock+0x76/0xa0
_raw_spin_lock_irqsave+0x72/0x80
uart_write_room+0x3b/0xc0
gsm_data_kick+0x14b/0x240 [n_gsm]
gsmld_write_wakeup+0x35/0x70 [n_gsm]
tty_wakeup+0x53/0x60
tty_port_default_wakeup+0x1b/0x30
serial8250_tx_chars+0x12f/0x220
serial8250_handle_irq.part.0+0xfe/0x150
serial8250_default_handle_irq+0x48/0x80
serial8250_interrupt+0x56/0xa0
__handle_irq_event_percpu+0x78/0x1f0
handle_irq_event+0x34/0x70
handle_fasteoi_irq+0x90/0x1e0
__common_interrupt+0x69/0x100
common_interrupt+0x48/0xc0
asm_common_interrupt+0x1e/0x40
RIP: 0010:__do_softirq+0x83/0x34e
Code: 2a 0a ff 0f b7 ed c7 44 24 10 0a 00 00 00 48 c7 c7 51 2a 64 82 e8 2d
e2 d5 ff 65 66 c7 05 83 af 1e 7e 00 00 fb b8 ff ff ff ff <49> c7 c2 40 61
80 82 0f bc c5 41 89 c4 41 83 c4 01 0f 84 e6 00 00
RSP: 0018:ffffc90000003f98 EFLAGS: 00000286
RAX: 00000000ffffffff RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffffffff82642a51 RDI: ffffffff825bb5e7
RBP: 0000000000000200 R08: 00000008de3271a8 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000030 R14: 0000000000000000 R15: 0000000000000000
? __do_softirq+0x73/0x34e
irq_exit_rcu+0xb5/0x100
common_interrupt+0xa4/0xc0
</IRQ>
<TASK>
asm_common_interrupt+0x1e/0x40
RIP: 0010:_raw_spin_unlock_irqrestore+0x2e/0x50
Code: 00 55 48 89 fd 48 83 c7 18 53 48 89 f3 48 8b 74 24 10 e8 85 28 36 ff
48 89 ef e8 cd 58 36 ff 80 e7 02 74 01 fb bf 01 00 00 00 <e8> 3d 97 33 ff
65 8b 05 96 23 2b 7e 85 c0 74 03 5b 5d c3 0f 1f 44
RSP: 0018:ffffc9000020fd08 EFLAGS: 00000202
RAX: 0000000000000000 RBX: 0000000000000246 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff8257fd74 RDI: 0000000000000001
RBP: ffff8880057de3a0 R08: 00000008de233000 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000100 R14: 0000000000000202 R15: ffff8880057df0b8
? _raw_spin_unlock_irqrestore+0x23/0x50
gsmtty_write+0x65/0x80 [n_gsm]
n_tty_write+0x33f/0x530
? swake_up_all+0xe0/0xe0
file_tty_write.constprop.0+0x1b1/0x320
? n_tty_flush_buffer+0xb0/0xb0
new_sync_write+0x10c/0x190
vfs_write+0x282/0x310
ksys_write+0x68/0xe0
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
RIP: 0033:0x7f3e5e35c15c
Code: 8b 7c 24 08 89 c5 e8 c5 ff ff ff 89 ef 89 44 24
---truncated--- |
| In the Linux kernel, the following vulnerability has been resolved:
net: skbuff: propagate shared-frag marker through frag-transfer helpers
Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail
to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when
moving frags from source to destination. __pskb_copy_fclone() defers
the rest of the shinfo metadata to skb_copy_header() after copying
frag descriptors, but that helper only carries over gso_{size,segs,
type} and never touches skb_shinfo()->flags; skb_shift() moves frag
descriptors directly and leaves flags untouched. As a result, the
destination skb keeps a reference to the same externally-owned or
page-cache-backed pages while reporting skb_has_shared_frag() as
false.
The mismatch is harmful in any in-place writer that uses
skb_has_shared_frag() to decide whether shared pages must be detoured
through skb_cow_data(). ESP input is one such writer (esp4.c,
esp6.c), and a single nft 'dup to <local>' rule -- or any other
nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d
skb in esp_input() with the marker stripped, letting an unprivileged
user write into the page cache of a root-owned read-only file via
authencesn-ESN stray writes.
Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors
were actually moved from the source. skb_copy() and skb_copy_expand()
share skb_copy_header() too but linearize all paged data into freshly
allocated head storage and emerge with nr_frags == 0, so
skb_has_shared_frag() returns false on its own; they need no change.
The same omission exists in skb_gro_receive() and skb_gro_receive_list().
The former moves the incoming skb's frag descriptors into the
accumulator's last sub-skb via two paths (a direct frag-move loop and
the head_frag + memcpy path); the latter chains the incoming skb whole
onto p's frag_list. Downstream skb_segment() reads only
skb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's
shinfo as the nskb -- both p and lp must carry the marker.
The same omission also exists in tcp_clone_payload(), which builds an
MTU probe skb by moving frag descriptors from skbs on sk_write_queue
into a freshly allocated nskb. The helper falls into the same family
and warrants the same fix for consistency; no TCP TX-side in-place
writer is currently known to reach a user page through this gap, but
a future consumer depending on the marker would regress silently.
The same omission exists in skb_segment(): the per-iteration flag
merge takes only head_skb's flag, and the inner switch that rebinds
frag_skb to list_skb on head_skb-frags exhaustion does not fold the
new frag_skb's flag into nskb. Fold frag_skb's flag at both sites
so segments drawing frags from frag_list members carry the marker. |
| In the Linux kernel, the following vulnerability has been resolved:
serial: 8250: Fix TX deadlock when using DMA
`dmaengine_terminate_async` does not guarantee that the
`__dma_tx_complete` callback will run. The callback is currently the
only place where `dma->tx_running` gets cleared. If the transaction is
canceled and the callback never runs, then `dma->tx_running` will never
get cleared and we will never schedule new TX DMA transactions again.
This change makes it so we clear `dma->tx_running` after we terminate
the DMA transaction. This is "safe" because `serial8250_tx_dma_flush`
is holding the UART port lock. The first thing the callback does is also
grab the UART port lock, so access to `dma->tx_running` is serialized. |
| In the Linux kernel, the following vulnerability has been resolved:
ksmbd: call ksmbd_vfs_kern_path_end_removing() on some error paths
There are two places where ksmbd_vfs_kern_path_end_removing() needs to be
called in order to balance what the corresponding successful call to
ksmbd_vfs_kern_path_start_removing() has done, i.e. drop inode locks and
put the taken references. Otherwise there might be potential deadlocks
and unbalanced locks which are caught like:
BUG: workqueue leaked lock or atomic: kworker/5:21/0x00000000/7596
last function: handle_ksmbd_work
2 locks held by kworker/5:21/7596:
#0: ffff8881051ae448 (sb_writers#3){.+.+}-{0:0}, at: ksmbd_vfs_kern_path_locked+0x142/0x660
#1: ffff888130e966c0 (&type->i_mutex_dir_key#3/1){+.+.}-{4:4}, at: ksmbd_vfs_kern_path_locked+0x17d/0x660
CPU: 5 PID: 7596 Comm: kworker/5:21 Not tainted 6.1.162-00456-gc29b353f383b #138
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014
Workqueue: ksmbd-io handle_ksmbd_work
Call Trace:
<TASK>
dump_stack_lvl+0x44/0x5b
process_one_work.cold+0x57/0x5c
worker_thread+0x82/0x600
kthread+0x153/0x190
ret_from_fork+0x22/0x30
</TASK>
Found by Linux Verification Center (linuxtesting.org). |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Fix deadlocks between devlink and netdev instance locks
In the mentioned "Fixes" commit, various work tasks triggering devlink
health reporter recovery were switched to use netdev_trylock to protect
against concurrent tear down of the channels being recovered. But this
had the side effect of introducing potential deadlocks because of
incorrect lock ordering.
The correct lock order is described by the init flow:
probe_one -> mlx5_init_one (acquires devlink lock)
-> mlx5_init_one_devl_locked -> mlx5_register_device
-> mlx5_rescan_drivers_locked -...-> mlx5e_probe -> _mlx5e_probe
-> register_netdev (acquires rtnl lock)
-> register_netdevice (acquires netdev lock)
=> devlink lock -> rtnl lock -> netdev lock.
But in the current recovery flow, the order is wrong:
mlx5e_tx_err_cqe_work (acquires netdev lock)
-> mlx5e_reporter_tx_err_cqe -> mlx5e_health_report
-> devlink_health_report (acquires devlink lock => boom!)
-> devlink_health_reporter_recover
-> mlx5e_tx_reporter_recover -> mlx5e_tx_reporter_recover_from_ctx
-> mlx5e_tx_reporter_err_cqe_recover
The same pattern exists in:
mlx5e_reporter_rx_timeout
mlx5e_reporter_tx_ptpsq_unhealthy
mlx5e_reporter_tx_timeout
Fix these by moving the netdev_trylock calls from the work handlers
lower in the call stack, in the respective recovery functions, where
they are actually necessary. |
| In the Linux kernel, the following vulnerability has been resolved:
net: mscc: ocelot: add missing lock protection in ocelot_port_xmit_inj()
ocelot_port_xmit_inj() calls ocelot_can_inject() and
ocelot_port_inject_frame() without holding the injection group lock.
Both functions contain lockdep_assert_held() for the injection lock,
and the correct caller felix_port_deferred_xmit() properly acquires
the lock using ocelot_lock_inj_grp() before calling these functions.
Add ocelot_lock_inj_grp()/ocelot_unlock_inj_grp() around the register
injection path to fix the missing lock protection. The FDMA path is not
affected as it uses its own locking mechanism. |
| In the Linux kernel, the following vulnerability has been resolved:
batman-adv: Avoid double-rtnl_lock ELP metric worker
batadv_v_elp_get_throughput() might be called when the RTNL lock is already
held. This could be problematic when the work queue item is cancelled via
cancel_delayed_work_sync() in batadv_v_elp_iface_disable(). In this case,
an rtnl_lock() would cause a deadlock.
To avoid this, rtnl_trylock() was used in this function to skip the
retrieval of the ethtool information in case the RTNL lock was already
held.
But for cfg80211 interfaces, batadv_get_real_netdev() was called - which
also uses rtnl_lock(). The approach for __ethtool_get_link_ksettings() must
also be used instead and the lockless version __batadv_get_real_netdev()
has to be called. |
| In the Linux kernel, the following vulnerability has been resolved:
drm/imagination: Fix deadlock in soft reset sequence
The soft reset sequence is currently executed from the threaded IRQ
handler, hence it cannot call disable_irq() which internally waits
for IRQ handlers, i.e. itself, to complete.
Use disable_irq_nosync() during a soft reset instead. |
| In the Linux kernel, the following vulnerability has been resolved:
crypto: algif_aead - Revert to operating out-of-place
This mostly reverts commit 72548b093ee3 except for the copying of
the associated data.
There is no benefit in operating in-place in algif_aead since the
source and destination come from different mappings. Get rid of
all the complexity added for in-place operation and just copy the
AD directly. |
| In the Linux kernel, the following vulnerability has been resolved:
net/mlx5: Fix deadlock between devlink lock and esw->wq
esw->work_queue executes esw_functions_changed_event_handler ->
esw_vfs_changed_event_handler and acquires the devlink lock.
.eswitch_mode_set (acquires devlink lock in devlink_nl_pre_doit) ->
mlx5_devlink_eswitch_mode_set -> mlx5_eswitch_disable_locked ->
mlx5_eswitch_event_handler_unregister -> flush_workqueue deadlocks
when esw_vfs_changed_event_handler executes.
Fix that by no longer flushing the work to avoid the deadlock, and using
a generation counter to keep track of work relevance. This avoids an old
handler manipulating an esw that has undergone one or more mode changes:
- the counter is incremented in mlx5_eswitch_event_handler_unregister.
- the counter is read and passed to the ephemeral mlx5_host_work struct.
- the work handler takes the devlink lock and bails out if the current
generation is different than the one it was scheduled to operate on.
- mlx5_eswitch_cleanup does the final draining before destroying the wq.
No longer flushing the workqueue has the side effect of maybe no longer
cancelling pending vport_change_handler work items, but that's ok since
those are disabled elsewhere:
- mlx5_eswitch_disable_locked disables the vport eq notifier.
- mlx5_esw_vport_disable disarms the HW EQ notification and marks
vport->enabled under state_lock to false to prevent pending vport
handler from doing anything.
- mlx5_eswitch_cleanup destroys the workqueue and makes sure all events
are disabled/finished. |
| In the Linux kernel, the following vulnerability has been resolved:
USB: dummy-hcd: Fix locking/synchronization error
Syzbot testing was able to provoke an addressing exception and crash
in the usb_gadget_udc_reset() routine in
drivers/usb/gadgets/udc/core.c, resulting from the fact that the
routine was called with a second ("driver") argument of NULL. The bad
caller was set_link_state() in dummy_hcd.c, and the problem arose
because of a race between a USB reset and driver unbind.
These sorts of races were not supposed to be possible; commit
7dbd8f4cabd9 ("USB: dummy-hcd: Fix erroneous synchronization change"),
along with a few followup commits, was written specifically to prevent
them. As it turns out, there are (at least) two errors remaining in
the code. Another patch will address the second error; this one is
concerned with the first.
The error responsible for the syzbot crash occurred because the
stop_activity() routine will sometimes drop and then re-acquire the
dum->lock spinlock. A call to stop_activity() occurs in
set_link_state() when handling an emulated USB reset, after the test
of dum->ints_enabled and before the increment of dum->callback_usage.
This allowed another thread (doing a driver unbind) to sneak in and
grab the spinlock, and then clear dum->ints_enabled and dum->driver.
Normally this other thread would have to wait for dum->callback_usage
to go down to 0 before it would clear dum->driver, but in this case it
didn't have to wait since dum->callback_usage had not yet been
incremented.
The fix is to increment dum->callback_usage _before_ calling
stop_activity() instead of after. Then the thread doing the unbind
will not clear dum->driver until after the call to
usb_gadget_udc_reset() safely returns and dum->callback_usage has been
decremented again. |
| In the Linux kernel, the following vulnerability has been resolved:
octeontx2-af: Workaround SQM/PSE stalls by disabling sticky
NIX SQ manager sticky mode is known to cause stalls when multiple SQs
share an SMQ and transmit concurrently. Additionally, PSE may deadlock
on transitions between sticky and non-sticky transmissions. There is
also a credit drop issue observed when certain condition clocks are
gated.
work around these hardware errata by:
- Disabling SQM sticky operation:
- Clear TM6 (bit 15)
- Clear TM11 (bit 14)
- Disabling sticky → non-sticky transition path that can deadlock PSE:
- Clear TM5 (bit 23)
- Preventing credit drops by keeping the control-flow clock enabled:
- Set TM9 (bit 21)
These changes are applied via NIX_AF_SQM_DBG_CTL_STATUS. With this
configuration the SQM/PSE maintain forward progress under load without
credit loss, at the cost of disabling sticky optimizations. |
| In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: L2CAP: Fix deadlock in l2cap_conn_del()
l2cap_conn_del() calls cancel_delayed_work_sync() for both info_timer
and id_addr_timer while holding conn->lock. However, the work functions
l2cap_info_timeout() and l2cap_conn_update_id_addr() both acquire
conn->lock, creating a potential AB-BA deadlock if the work is already
executing when l2cap_conn_del() takes the lock.
Move the work cancellations before acquiring conn->lock and use
disable_delayed_work_sync() to additionally prevent the works from
being rearmed after cancellation, consistent with the pattern used in
hci_conn_del(). |
| In the Linux kernel, the following vulnerability has been resolved:
Revert "PCI/IOV: Add PCI rescan-remove locking when enabling/disabling SR-IOV"
This reverts commit 05703271c3cd ("PCI/IOV: Add PCI rescan-remove locking
when enabling/disabling SR-IOV"), which causes a deadlock by recursively
taking pci_rescan_remove_lock when sriov_del_vfs() is called as part of
pci_stop_and_remove_bus_device(). For example with the following sequence
of commands:
$ echo <NUM> > /sys/bus/pci/devices/<pf>/sriov_numvfs
$ echo 1 > /sys/bus/pci/devices/<pf>/remove
A trimmed trace of the deadlock on a mlx5 device is as below:
zsh/5715 is trying to acquire lock:
000002597926ef50 (pci_rescan_remove_lock){+.+.}-{3:3}, at: sriov_disable+0x34/0x140
but task is already holding lock:
000002597926ef50 (pci_rescan_remove_lock){+.+.}-{3:3}, at: pci_stop_and_remove_bus_device_locked+0x24/0x80
...
Call Trace:
[<00000259778c4f90>] dump_stack_lvl+0xc0/0x110
[<00000259779c844e>] print_deadlock_bug+0x31e/0x330
[<00000259779c1908>] __lock_acquire+0x16c8/0x32f0
[<00000259779bffac>] lock_acquire+0x14c/0x350
[<00000259789643a6>] __mutex_lock_common+0xe6/0x1520
[<000002597896413c>] mutex_lock_nested+0x3c/0x50
[<00000259784a07e4>] sriov_disable+0x34/0x140
[<00000258f7d6dd80>] mlx5_sriov_disable+0x50/0x80 [mlx5_core]
[<00000258f7d5745e>] remove_one+0x5e/0xf0 [mlx5_core]
[<00000259784857fc>] pci_device_remove+0x3c/0xa0
[<000002597851012e>] device_release_driver_internal+0x18e/0x280
[<000002597847ae22>] pci_stop_bus_device+0x82/0xa0
[<000002597847afce>] pci_stop_and_remove_bus_device_locked+0x5e/0x80
[<00000259784972c2>] remove_store+0x72/0x90
[<0000025977e6661a>] kernfs_fop_write_iter+0x15a/0x200
[<0000025977d7241c>] vfs_write+0x24c/0x300
[<0000025977d72696>] ksys_write+0x86/0x110
[<000002597895b61c>] __do_syscall+0x14c/0x400
[<000002597896e0ee>] system_call+0x6e/0x90
This alone is not a complete fix as it restores the issue the cited commit
tried to solve. A new fix will be provided as a follow on. |
