lib/scatterlist: fix length calculations in extract_kvec_to_sg_CVE-2026-46289

9.8 / 10

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Description

In the Linux kernel, the following vulnerability has been resolved:

lib/scatterlist: fix length calculations in extract_kvec_to_sg

Patch series "Fix bugs in extract_iter_to_sg()", v3.

Fix bugs in the kvec and user variants of extract_iter_to_sg. This series
is growing due to useful remarks made by sashiko.dev.

The main bugs are:
- The length for an sglist entry when extracting from
a kvec can exceed the number of bytes in the page. This
is obviously not intended.
- When extracting a user buffer the sglist is temporarily
used as a scratch buffer for extracted page pointers.
If the sglist already contains some elements this scratch
buffer could overlap with existing entries in the sglist.

The series adds test cases to the kunit_iov_iter test that demonstrate all
of these bugs. Additionally, there is a memory leak fix for the test
itself.

The bugs were orignally introduced into kernel v6.3 where the function
lived in fs/netfs/iterator.c. It was later moved to lib/scatterlist.c in
v6.5. Thus the actual fix is only marked for backports to v6.5+.

This patch (of 5):

When extracting from a kvec to a scatterlist, do not cross page
boundaries. The required length was already calculated but not used as
intended.

Adjust the copied length if the loop runs out of sglist entries without
extracting everything.

While there, return immediately from extract_iter_to_sg if there are no
sglist entries at all.

A subsequent commit will add kunit test cases that demonstrate that the
patch is necessary.

AI Analysis

A vulnerability in the Linux kernel's lib/scatterlist module allows for the extraction of data beyond page boundaries, potentially leading to data corruption or information disclosure.

Basic Information

ID CVE-2026-46289

Source Linux

Published Jun 8, 2026 at 15:46

Modified Jun 14, 2026 at 04:30

Affected Product

Vendor Linux

Product Linux

Version 0185846975339a5c348373aa450a977f5242366b

Affected Versions Linux Linux 0185846975339a5c348373aa450a977f5242366b
Linux Linux 0185846975339a5c348373aa450a977f5242366b
Linux Linux 0185846975339a5c348373aa450a977f5242366b
Linux Linux 0185846975339a5c348373aa450a977f5242366b
Linux Linux 0185846975339a5c348373aa450a977f5242366b
Linux Linux 6.3

AI Assessment

AI Score 9.8 / 10

AI Severity CRITICAL

Vendor The Linux Foundation

Product Linux Kernel

Version 6.3, 6.5

References

{
    "lastseen": "",
    "description": "In the Linux kernel, the following vulnerability has been resolved:\n\nlib/scatterlist: fix length calculations in extract_kvec_to_sg\n\nPatch series \"Fix bugs in extract_iter_to_sg()\", v3.\n\nFix bugs in the kvec and user variants of extract_iter_to_sg.  This series\nis growing due to useful remarks made by sashiko.dev.\n\nThe main bugs are:\n- The length for an sglist entry when extracting from\n  a kvec can exceed the number of bytes in the page. This\n  is obviously not intended.\n- When extracting a user buffer the sglist is temporarily\n  used as a scratch buffer for extracted page pointers.\n  If the sglist already contains some elements this scratch\n  buffer could overlap with existing entries in the sglist.\n\nThe series adds test cases to the kunit_iov_iter test that demonstrate all\nof these bugs.  Additionally, there is a memory leak fix for the test\nitself.\n\nThe bugs were orignally introduced into kernel v6.3 where the function\nlived in fs/netfs/iterator.c.  It was later moved to lib/scatterlist.c in\nv6.5.  Thus the actual fix is only marked for backports to v6.5+.\n\n\nThis patch (of 5):\n\nWhen extracting from a kvec to a scatterlist, do not cross page\nboundaries.  The required length was already calculated but not used as\nintended.\n\nAdjust the copied length if the loop runs out of sglist entries without\nextracting everything.\n\nWhile there, return immediately from extract_iter_to_sg if there are no\nsglist entries at all.\n\nA subsequent commit will add kunit test cases that demonstrate that the\npatch is necessary.",
    "published": "2026-06-08T15:46:15.888Z",
    "modified": "2026-06-14T04:30:01.486Z",
    "type": "cve",
    "title": "lib/scatterlist: fix length calculations in extract_kvec_to_sg",
    "source": "Linux",
    "references": "https://git.kernel.org/stable/c/3f17500e86d730c76db638bb3ae52f9b5e496c76\nhttps://git.kernel.org/stable/c/e5e22fc9963469e678c4f4bb38d26adcec107f1e\nhttps://git.kernel.org/stable/c/8fbba6829057979149d1b37d65690c037f3ddf4d\nhttps://git.kernel.org/stable/c/9d38756d0a93b66163554219fa9c3365f40c4035\nhttps://git.kernel.org/stable/c/07b7d66e65d9cfe6b9c2c34aa22cfcaac37a5c45",
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