6.12-stable review patch. If anyone has any objections, please let me know.
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From: Carolina Jubran cjubran@nvidia.com
[ Upstream commit eb41a264a3a576dc040ee37c3d9d6b7e2d9be968 ]
There's a race between disabling DIM and NAPI callbacks using the dim pointer on the RQ or SQ.
If NAPI checks the DIM state bit and sees it still set, it assumes `rq->dim` or `sq->dim` is valid. But if DIM gets disabled right after that check, the pointer might already be set to NULL, leading to a NULL pointer dereference in net_dim().
Fix this by calling `synchronize_net()` before freeing the DIM context. This ensures all in-progress NAPI callbacks are finished before the pointer is cleared.
Kernel log:
BUG: kernel NULL pointer dereference, address: 0000000000000000 ... RIP: 0010:net_dim+0x23/0x190 ... Call Trace: <TASK> ? __die+0x20/0x60 ? page_fault_oops+0x150/0x3e0 ? common_interrupt+0xf/0xa0 ? sysvec_call_function_single+0xb/0x90 ? exc_page_fault+0x74/0x130 ? asm_exc_page_fault+0x22/0x30 ? net_dim+0x23/0x190 ? mlx5e_poll_ico_cq+0x41/0x6f0 [mlx5_core] ? sysvec_apic_timer_interrupt+0xb/0x90 mlx5e_handle_rx_dim+0x92/0xd0 [mlx5_core] mlx5e_napi_poll+0x2cd/0xac0 [mlx5_core] ? mlx5e_poll_ico_cq+0xe5/0x6f0 [mlx5_core] busy_poll_stop+0xa2/0x200 ? mlx5e_napi_poll+0x1d9/0xac0 [mlx5_core] ? mlx5e_trigger_irq+0x130/0x130 [mlx5_core] __napi_busy_loop+0x345/0x3b0 ? sysvec_call_function_single+0xb/0x90 ? asm_sysvec_call_function_single+0x16/0x20 ? sysvec_apic_timer_interrupt+0xb/0x90 ? pcpu_free_area+0x1e4/0x2e0 napi_busy_loop+0x11/0x20 xsk_recvmsg+0x10c/0x130 sock_recvmsg+0x44/0x70 __sys_recvfrom+0xbc/0x130 ? __schedule+0x398/0x890 __x64_sys_recvfrom+0x20/0x30 do_syscall_64+0x4c/0x100 entry_SYSCALL_64_after_hwframe+0x4b/0x53 ... ---[ end trace 0000000000000000 ]--- ... ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
Fixes: 445a25f6e1a2 ("net/mlx5e: Support updating coalescing configuration without resetting channels") Signed-off-by: Carolina Jubran cjubran@nvidia.com Reviewed-by: Cosmin Ratiu cratiu@nvidia.com Signed-off-by: Tariq Toukan tariqt@nvidia.com Reviewed-by: Jacob Keller jacob.e.keller@intel.com Link: https://patch.msgid.link/1752155624-24095-3-git-send-email-tariqt@nvidia.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/mellanox/mlx5/core/en_dim.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_dim.c b/drivers/net/ethernet/mellanox/mlx5/core/en_dim.c index 298bb74ec5e94..d1d629697e285 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_dim.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_dim.c @@ -113,7 +113,7 @@ int mlx5e_dim_rx_change(struct mlx5e_rq *rq, bool enable) __set_bit(MLX5E_RQ_STATE_DIM, &rq->state); } else { __clear_bit(MLX5E_RQ_STATE_DIM, &rq->state); - + synchronize_net(); mlx5e_dim_disable(rq->dim); rq->dim = NULL; } @@ -140,7 +140,7 @@ int mlx5e_dim_tx_change(struct mlx5e_txqsq *sq, bool enable) __set_bit(MLX5E_SQ_STATE_DIM, &sq->state); } else { __clear_bit(MLX5E_SQ_STATE_DIM, &sq->state); - + synchronize_net(); mlx5e_dim_disable(sq->dim); sq->dim = NULL; }