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…

Overview

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

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.