CVE-2026-64122 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Fix use-after-free in mlx5e_tx_reporter_timeout_recover
mlx5e_tx_reporter_timeout_recover() accesses sq->netdev after mlx5e_safe_reopen_channels() has torn down and freed the channel (and its embedded SQs). Replace the three sq->netdev references with priv->netdev which is safe because priv outlives channel teardown.
The netdev_err() call already used priv->netdev for this reason; make the trylock/unlock and health_channel_eq_recover calls consistent.
This fixes the following KASAN splat:
BUG: KASAN: use-after-free in mlx5e_tx_reporter_timeout_recover+0x1dd/0x360 [mlx5_core]
Read of size 8 at addr ffff889860ed0b28 by task kworker/u113:2/5277
Call Trace: mlx5e_tx_reporter_timeout_recover+0x1dd/0x360 [mlx5_core]
devlink_health_reporter_recover+0xa2/0x150 devlink_health_report+0x254/0x7c0 mlx5e_reporter_tx_timeout+0x297/0x380 [mlx5_core]
mlx5e_tx_timeout_work+0x109/0x170 [mlx5_core]
process_one_work+0x677/0xf20 worker_thread+0x51f/0xd90 kthread+0x3a5/0x810 ret_from_fork+0x208/0x400 ret_from_fork_asm+0x1a/0x30
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Analysis
by VulDB Data Team • 07/19/2026
The vulnerability described represents a critical use-after-free condition in the Mellanox ConnectX-5 network driver component of the Linux kernel. This flaw occurs within the mlx5e_tx_reporter_timeout_recover function where the code attempts to access a network device reference after the underlying channel structure has already been torn down and freed. The issue stems from improper resource management during error recovery operations, specifically when handling timeout conditions in the transmit path of Mellanox network adapters.
The technical root cause involves the manipulation of shared data structures where sq->netdev references are accessed after channel teardown has occurred. When mlx5e_safe_reopen_channels() executes, it destroys and frees the channel along with its embedded SQs, but the mlx5e_tx_reporter_timeout_recover function continues to reference these freed resources through sq->netdev. This creates a scenario where memory that has been deallocated is being accessed, leading to undefined behavior and potential system crashes.
This vulnerability manifests as a KASAN (Kernel Address Sanitizer) detection event with a specific memory access pattern showing a read of size 8 at address ffff889860ed0b28. The call trace demonstrates the execution path leading to the use-after-free condition, beginning from mlx5e_tx_reporter_timeout_recover and flowing through devlink_health_reporter_recover, ultimately triggered by mlx5e_reporter_tx_timeout and mlx5e_tx_timeout_work. The issue aligns with CWE-416, which addresses Use After Free conditions in software systems.
The operational impact of this vulnerability extends beyond simple memory corruption to potentially compromise system stability and network functionality. When triggered, the use-after-free condition can cause kernel panics, system crashes, or unpredictable behavior in network operations. The affected driver component handles critical transmit timeout recovery mechanisms that are essential for maintaining network connectivity and performance on Mellanox hardware platforms.
The fix implemented addresses this by replacing all sq->netdev references with priv->netdev throughout the mlx5e_tx_reporter_timeout_recover function. This change ensures that only safe references are used during the error recovery process since the private driver context (priv) maintains a longer lifetime than individual channel structures. The solution also standardizes the locking and recovery operations to be consistent with existing patterns within the same codebase, specifically aligning with how netdev_err() already properly utilizes priv->netdev for this purpose.
This remediation approach follows established security best practices and aligns with ATT&CK framework concept T1499.004, which addresses network denial of service through resource exhaustion or corruption. The fix ensures that memory access patterns conform to proper resource lifecycle management principles, preventing unauthorized access to deallocated kernel memory structures. The solution maintains the functional integrity of the timeout recovery mechanism while eliminating the potential for system instability and security vulnerabilities associated with improper memory handling in kernel space network drivers.