Description

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

ext4: avoid use-after-free in ext4_ext_show_leaf()

In ext4_find_extent(), path may be freed by error or be reallocated, so
using a previously saved *ppath may have been freed and thus may trigger
use-after-free, as follows:

ext4_split_extent
path = *ppath;
ext4_split_extent_at(ppath)
path = ext4_find_extent(ppath)
ext4_split_extent_at(ppath)
// ext4_find_extent fails to free path
// but zeroout succeeds
ext4_ext_show_leaf(inode, path)
eh = path[depth].p_hdr
// path use-after-free !!!

Similar to ext4_split_extent_at(), we use *ppath directly as an input to
ext4_ext_show_leaf(). Fix a spelling error by the way.

Same problem in ext4_ext_handle_unwritten_extents(). Since 'path' is only
used in ext4_ext_show_leaf(), remove 'path' and use *ppath directly.

This issue is triggered only when EXT_DEBUG is defined and therefore does
not affect functionality.

Classification

CVE ID: CVE-2024-49889

CVSS Base Severity: HIGH

CVSS Base Score: 7.8

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

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.03% (probability of being exploited)

EPSS Percentile: 6.84% (scored less or equal to compared to others)

EPSS Date: 2025-06-02 (when was this score calculated)

Stakeholder-Specific Vulnerability Categorization (SSVC)

SSVC Exploitation: none

SSVC Technical Impact: partial

SSVC Automatable: false

References

https://nvd.nist.gov/vuln/detail/CVE-2024-49889
https://git.kernel.org/stable/c/b0cb4561fc4284d04e69c8a66c8504928ab2484e
https://git.kernel.org/stable/c/4999fed877bb64e3e7f9ab9996de2ca983c41928
https://git.kernel.org/stable/c/2eba3b0cc5b8de624918d21f32b5b8db59a90b39
https://git.kernel.org/stable/c/34b2096380ba475771971a778a478661a791aa15
https://git.kernel.org/stable/c/8b114f2cc7dd5d36729d040b68432fbd0f0a8868
https://git.kernel.org/stable/c/d483c7cc1796bd6a80e7b3a8fd494996260f6b67
https://git.kernel.org/stable/c/4e2524ba2ca5f54bdbb9e5153bea00421ef653f5

Timeline