CVE-2026-46289
Received Received - Intake
Linux Kernel Scatterlist Length Calculation Vulnerability

Publication date: 2026-06-08

Last updated on: 2026-06-08

Assigner: kernel.org

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.
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Meta Information
Published
2026-06-08
Last Modified
2026-06-08
Generated
2026-06-09
AI Q&A
2026-06-08
EPSS Evaluated
N/A
NVD
CVE-2026-46289
EUVD
EUVD-2026-35155
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel From 6.5 (inc)
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CWE ID Description
CWE-UNKNOWN
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Executive Summary

This vulnerability exists in the Linux kernel's scatterlist handling code, specifically in the function extract_iter_to_sg and its variants dealing with kvec and user buffers.

The main issues are incorrect length calculations when extracting data from a kvec to a scatterlist, which can cause the length for an sglist entry to exceed the number of bytes in a memory page. Additionally, when extracting from a user buffer, the scatterlist is temporarily used as a scratch buffer, which can overlap with existing entries if the scatterlist already contains elements.

These bugs were introduced in kernel version 6.3 and later moved to a different source file in version 6.5. The patch fixes these bugs by ensuring lengths do not cross page boundaries, adjusting copied lengths if the scatterlist runs out of entries, and returning early if no scatterlist entries are available.

Impact Analysis

This vulnerability can lead to incorrect memory handling in the Linux kernel when dealing with scatterlists, potentially causing data corruption or memory safety issues.

Specifically, length miscalculations might cause buffer overflows or overlapping memory regions, which could result in unexpected behavior or crashes in kernel operations that rely on scatterlists.

While the exact impact depends on how the kernel and applications use these functions, such bugs can undermine system stability and security.

Mitigation Strategies

The vulnerability is fixed in Linux kernel version 6.5 and later. Immediate mitigation involves updating your Linux kernel to version 6.5 or a later version that includes the patch fixing the bugs in extract_iter_to_sg.

If updating the kernel immediately is not possible, consider applying the patch series "Fix bugs in extract_iter_to_sg()" (v3) manually to your current kernel source and rebuilding the kernel.

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