vulnerability

Red Hat: CVE-2024-49889: kernel: ext4: avoid use-after-free in ext4_ext_show_leaf() (Multiple Advisories)

Severity
7
CVSS
(AV:L/AC:L/Au:M/C:C/I:C/A:C)
Published
Oct 21, 2024
Added
May 15, 2025
Modified
May 15, 2025

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.

Solution(s)

redhat-upgrade-kernelredhat-upgrade-kernel-rt
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