CVE-2026-31437 (GCVE-0-2026-31437)

Vulnerability from cvelistv5 – Published: 2026-04-22 13:53 – Updated: 2026-05-11 22:08
VLAI?
Title
netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry
Summary
In the Linux kernel, the following vulnerability has been resolved: netfs: Fix NULL pointer dereference in netfs_unbuffered_write() on retry When a write subrequest is marked NETFS_SREQ_NEED_RETRY, the retry path in netfs_unbuffered_write() unconditionally calls stream->prepare_write() without checking if it is NULL. Filesystems such as 9P do not set the prepare_write operation, so stream->prepare_write remains NULL. When get_user_pages() fails with -EFAULT and the subrequest is flagged for retry, this results in a NULL pointer dereference at fs/netfs/direct_write.c:189. Fix this by mirroring the pattern already used in write_retry.c: if stream->prepare_write is NULL, skip renegotiation and directly reissue the subrequest via netfs_reissue_write(), which handles iterator reset, IN_PROGRESS flag, stats update and reissue internally.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 72d08d2839649d1c5efbe375751f4473fa4486af , < a4d1b4ba9754bac3efebd06f583a44a7af52c0ab (git)
Affected: 0c29f6d63122a0168d67cb8ecde5b4cf7fe4acb0 , < 7a5482f5ce891decbf36f2e6fab1e9fc4a76a684 (git)
Affected: a0b4c7a49137ed21279f354eb59f49ddae8dffc2 , < e9075e420a1eb3b52c60f3b95893a55e77419ce8 (git)
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Linux Linux Affected: 6.18.17 , < 6.18.21 (semver)
Affected: 6.19.7 , < 6.19.11 (semver)
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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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