Bug 2313092 (CVE-2024-46744)

Summary: CVE-2024-46744 kernel: Squashfs: sanity check symbolic link size
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Priority: medium    
Version: unspecifiedCC: dfreiber, drow, jburrell, vkumar
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Hardware: All   
OS: Linux   
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A vulnerability was found in the Linux kernel involving the use of uninitialized resources. When a corrupted symbolic link size read is called from the disk, it causes an uninitialized page, resulting in loss of availability of the system.
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Bug Depends On: 2313186    
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Description OSIDB Bzimport 2024-09-18 08:21:21 UTC 
In the Linux kernel, the following vulnerability has been resolved:

Squashfs: sanity check symbolic link size

Syzkiller reports a "KMSAN: uninit-value in pick_link" bug.

This is caused by an uninitialised page, which is ultimately caused
by a corrupted symbolic link size read from disk.

The reason why the corrupted symlink size causes an uninitialised
page is due to the following sequence of events:

1. squashfs_read_inode() is called to read the symbolic
   link from disk.  This assigns the corrupted value
   3875536935 to inode->i_size.

2. Later squashfs_symlink_read_folio() is called, which assigns
   this corrupted value to the length variable, which being a
   signed int, overflows producing a negative number.

3. The following loop that fills in the page contents checks that
   the copied bytes is less than length, which being negative means
   the loop is skipped, producing an uninitialised page.

This patch adds a sanity check which checks that the symbolic
link size is not larger than expected.

--

V2: fix spelling mistake.
Comment 1 Michal Findra 2024-09-18 09:37:01 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2024091836-CVE-2024-46744-451f@gregkh/T
Comment 3 errata-xmlrpc 2025-11-11 10:19:50 UTC 
This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2025:20518 https://access.redhat.com/errata/RHSA-2025:20518