CVE-2024-49883

ext4: aovid use-after-free in ext4_ext_insert_extent()

State: Published
Severity: 7.8 High
Published: Oct 21, 2024
Updated: Aug 5, 2026
Reserved: Oct 21, 2024

Description

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

ext4: aovid use-after-free in ext4_ext_insert_extent()

As Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is reallocated in ext4_ext_create_new_leaf(), we'll use the stale path and cause UAF. Below is a sample trace with dummy values:

ext4_ext_insert_extent path = *ppath = 2000 ext4_ext_create_new_leaf(ppath) ext4_find_extent(ppath) path = *ppath = 2000 if (depth > path[0].p_maxdepth) kfree(path = 2000); *ppath = path = NULL; path = kcalloc() = 3000 *ppath = 3000; return path; /* here path is still 2000, UAF! */ eh = path[depth].p_hdr

================================================================== BUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330 Read of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179 CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866 Call Trace: <TASK> ext4_ext_insert_extent+0x26d4/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 [...]

Allocated by task 179: ext4_find_extent+0x81c/0x1f70 ext4_ext_map_blocks+0x146/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...]

Freed by task 179: kfree+0xcb/0x240 ext4_find_extent+0x7c0/0x1f70 ext4_ext_insert_extent+0xa26/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] ==================================================================

So use *ppath to update the path to avoid the above problem.

Scores

CVSS	Score	Vector	Source
3.1	7.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	10809df84a4d868db61af621bae3658494165279 to before e17ebe4fdd7665c93ae9459ba40fcdfb76769ac1Affected 10809df84a4d868db61af621bae3658494165279 to before 975ca06f3fd154c5f7742083e7b2574c57d1c0c3Affected 10809df84a4d868db61af621bae3658494165279 to before 5e811066c5ab709b070659197dccfb80ab650dddAffected 10809df84a4d868db61af621bae3658494165279 to before 9df59009dfc6d9fc1bd9ddf6c5ab6e56d6ed887aAffected 10809df84a4d868db61af621bae3658494165279 to before 51db04892a993cace63415be99848970a0f15ef2Affected 10809df84a4d868db61af621bae3658494165279 to before 8162ee5d94b8c0351be0a9321be134872a7654a1Affected 10809df84a4d868db61af621bae3658494165279 to before beb7b66fb489041c50c6473100b383f7a51648fcAffected 10809df84a4d868db61af621bae3658494165279 to before bfed082ce4b1ce6349b05c09a0fa4f3da35ecb1bAffected 10809df84a4d868db61af621bae3658494165279 to before a164f3a432aae62ca23d03e6d926b122ee5b860dAffected
LinuxLinux	3.18Affected before 3.18Not affected 4.19.323 through 4.19.Not affected 5.4.285 through 5.4.Not affected 5.10.227 through 5.10.Not affected 5.15.168 through 5.15.Not affected 6.1.113 through 6.1.Not affected 6.6.55 through 6.6.Not affected 6.10.14 through 6.10.Not affected 6.11.3 through 6.11.Not affected 6.12 and laterNot affected

Product

Versions

LinuxLinux

10809df84a4d868db61af621bae3658494165279 to before e17ebe4fdd7665c93ae9459ba40fcdfb76769ac1Affected
10809df84a4d868db61af621bae3658494165279 to before 975ca06f3fd154c5f7742083e7b2574c57d1c0c3Affected
10809df84a4d868db61af621bae3658494165279 to before 5e811066c5ab709b070659197dccfb80ab650dddAffected
10809df84a4d868db61af621bae3658494165279 to before 9df59009dfc6d9fc1bd9ddf6c5ab6e56d6ed887aAffected
10809df84a4d868db61af621bae3658494165279 to before 51db04892a993cace63415be99848970a0f15ef2Affected
10809df84a4d868db61af621bae3658494165279 to before 8162ee5d94b8c0351be0a9321be134872a7654a1Affected
10809df84a4d868db61af621bae3658494165279 to before beb7b66fb489041c50c6473100b383f7a51648fcAffected
10809df84a4d868db61af621bae3658494165279 to before bfed082ce4b1ce6349b05c09a0fa4f3da35ecb1bAffected
10809df84a4d868db61af621bae3658494165279 to before a164f3a432aae62ca23d03e6d926b122ee5b860dAffected

LinuxLinux

3.18Affected
before 3.18Not affected
4.19.323 through 4.19.*Not affected
5.4.285 through 5.4.*Not affected
5.10.227 through 5.10.*Not affected
5.15.168 through 5.15.*Not affected
6.1.113 through 6.1.*Not affected
6.6.55 through 6.6.*Not affected
6.10.14 through 6.10.*Not affected
6.11.3 through 6.11.*Not affected
6.12 and laterNot affected

References

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