CVE-2026-99078 is a vulnerability in Linux Kernel
Published on October 23, 2026
net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
In the Linux kernel, the following vulnerability has been resolved:
net/mlx5e: Prevent stale XSK buffer release on MPWQE refill retry
With AF_XDP on a striding RQ, mlx5e defers releasing XSK buffers until
an MPWQE is refilled. If XSK allocation then returns -ENOMEM,
actual_wq_head is not advanced and a later NAPI poll retries the same
WQE.
mlx5e_free_rx_mpwqe() leaves each released slot marked as releasable. On
retry it can therefore call xsk_buff_free() again through stale pointers
after the frames have returned to the XSK pool and been reallocated.
Set all skip_release_bitmap bits in the common error path of
mlx5e_xsk_alloc_rx_mpwqe(). This matches mlx5e_alloc_rx_mpwqe(). A
successful allocation already clears the bitmap after replacing every
buffer, so retries become idempotent without changing the success path.
Fault injection forced three consecutive failures for one selected MPWQE.
Both an early allocation failure and a partial 8-of-16-buffer unwind
released the original 16 XSK buffers only once. Each error left a full
bitmap, the following NAPI retry skipped the release, and a later
successful allocation cleared it. A 20-second AF_XDP zero-copy pressure
run exercised 1,575,262 buffer allocation failures without invalid
descriptors, WQE errors, or kernel warnings.
Products Associated with CVE-2026-99078
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Affected Versions
Linux:- Version 4c2a1323680709078736a2886c754004e9fe42e6 and below f3a52e2ec2788a7f6b64137985c087188a54ad4f is affected.
- Version 4c2a1323680709078736a2886c754004e9fe42e6 and below d215d09606b0fcd18ad1eb532995782a21cea49d is affected.
- Version 4c2a1323680709078736a2886c754004e9fe42e6 and below 867119b4b588037724b85839d534465f0334d9bd is affected.
- Version 4c2a1323680709078736a2886c754004e9fe42e6 and below 3d73a1164a8c6b4461907a65cb6c022ea4fd39af is affected.
- Version 4c2a1323680709078736a2886c754004e9fe42e6 and below 63811edf512584c946e5e96b100e9e280703bbb5 is affected.
- Version 6.4 is affected.
- Before 6.4 is unaffected.
- Version 6.6.160, <= 6.6.* is unaffected.
- Version 6.12.113, <= 6.12.* is unaffected.
- Version 6.18.57, <= 6.18.* is unaffected.
- Version 7.2.11, <= 7.2.* is unaffected.
- Version 7.3, <= * is unaffected.