Description
In the Linux kernel, the following vulnerability has been resolved: ext4: update orig_path in ext4_find_extent() In ext4_find_extent(), if the path is not big enough, we free it and set *orig_path to NULL. But after reallocating and successfully initializing the path, we don't update *orig_path, in which case the caller gets a valid path but a NULL ppath, and this may cause a NULL pointer dereference or a path memory leak. For example: ext4_split_extent path = *ppath = 2000 ext4_find_extent if (depth > path[0].p_maxdepth) kfree(path = 2000); *orig_path = path = NULL; path = kcalloc() = 3000 ext4_split_extent_at(*ppath = NULL) path = *ppath; ex = path[depth].p_ext; // NULL pointer dereference! ================================================================== BUG: kernel NULL pointer dereference, address: 0000000000000010 CPU: 6 UID: 0 PID: 576 Comm: fsstress Not tainted 6.11.0-rc2-dirty #847 RIP: 0010:ext4_split_extent_at+0x6d/0x560 Call Trace: <TASK> ext4_split_extent.isra.0+0xcb/0x1b0 ext4_ext_convert_to_initialized+0x168/0x6c0 ext4_ext_handle_unwritten_extents+0x325/0x4d0 ext4_ext_map_blocks+0x520/0xdb0 ext4_map_blocks+0x2b0/0x690 ext4_iomap_begin+0x20e/0x2c0 [...] ================================================================== Therefore, *orig_path is updated when the extent lookup succeeds, so that the caller can safely use path or *ppath.
Product status
10809df84a4d868db61af621bae3658494165279 (git) before ec0c0beb9b777cdd1edd7df9b36e0f3e67e2bdff
10809df84a4d868db61af621bae3658494165279 (git) before 6766937d0327000ac1b87c97bbecdd28b0dd6599
10809df84a4d868db61af621bae3658494165279 (git) before a9fcb1717d75061d3653ed69365c8d45331815cd
10809df84a4d868db61af621bae3658494165279 (git) before 6801ed1298204d16a38571091e31178bfdc3c679
10809df84a4d868db61af621bae3658494165279 (git) before f55ecc58d07a6c1f6d6d5b5af125c25f8da0bda2
10809df84a4d868db61af621bae3658494165279 (git) before b63481b3a388ee2df9e295f97273226140422a42
10809df84a4d868db61af621bae3658494165279 (git) before 11b230100d6801c014fab2afabc8bdea304c1b96
10809df84a4d868db61af621bae3658494165279 (git) before 5b4b2dcace35f618fe361a87bae6f0d13af31bc1
3.18
Any version before 3.18
4.19.323 (semver)
5.10.227 (semver)
5.15.168 (semver)
6.1.113 (semver)
6.6.55 (semver)
6.10.14 (semver)
6.11.3 (semver)
6.12 (original_commit_for_fix)
References
lists.debian.org/debian-lts-announce/2025/03/msg00002.html
lists.debian.org/debian-lts-announce/2025/01/msg00001.html
git.kernel.org/...c/ec0c0beb9b777cdd1edd7df9b36e0f3e67e2bdff
git.kernel.org/...c/6766937d0327000ac1b87c97bbecdd28b0dd6599
git.kernel.org/...c/a9fcb1717d75061d3653ed69365c8d45331815cd
git.kernel.org/...c/6801ed1298204d16a38571091e31178bfdc3c679
git.kernel.org/...c/f55ecc58d07a6c1f6d6d5b5af125c25f8da0bda2
git.kernel.org/...c/b63481b3a388ee2df9e295f97273226140422a42
git.kernel.org/...c/11b230100d6801c014fab2afabc8bdea304c1b96
git.kernel.org/...c/5b4b2dcace35f618fe361a87bae6f0d13af31bc1
