published September 17, 2026
In the Linux kernel, the following vulnerability has been resolved:
net: sparx5: fix sleep in atomic context in MAC table access
sparx5_set_rx_mode() runs with netif_addr_lock_bh held and iterates
dev->mc via __dev_mc_sync(), which per address calls sparx5_mc_sync() /
sparx5_mc_unsync() -> sparx5_mact_learn() / sparx5_mact_forget(). These
take sparx5->lock, a mutex, and then poll the MAC access command
register with readx_poll_timeout(). A mutex may block, which is not
allowed from atomic context.
Convert the driver to the new .ndo_set_rx_mode_async callback introduced
in commit 3554b4345d85 ("net: introduce ndo_set_rx_mode_async and
netdev_rx_mode_work"). The async callback is invoked from process
context, so the mutex and sleeping completion poll can remain.
Observed with CONFIG_PROVE_LOCKING, CONFIG_DEBUG_SPINLOCK,
CONFIG_DEBUG_MUTEXES and CONFIG_DEBUG_ATOMIC_SLEEP enabled:
BUG: sleeping function called from invalid context at kernel/locking/mutex.c:591
in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 217, name: ip
preempt_count: 201, expected: 0
Call trace:
__might_resched+0x144/0x248
__might_sleep+0x48/0x7c
__mutex_lock+0x74/0x850
mutex_lock_nested+0x24/0x30
sparx5_mact_learn+0x78/0x100
sparx5_mc_sync+0x40/0x54
__hw_addr_sync_dev+0xc4/0x170
sparx5_set_rx_mode+0x4c/0x58
__dev_set_rx_mode+0x64/0xa4
__dev_open+0x1ec/0x26c