Use After Free Affecting kernel-doc package, versions *
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-RHEL8-KERNELDOC-8287370
- published23 Oct 2024
- disclosed21 Oct 2024
Introduced: 21 Oct 2024
CVE-2024-49884 (opens in a new tab)How to fix?
There is no fixed version for RHEL:8 kernel-doc.
NVD Description
Note: Versions mentioned in the description apply only to the upstream kernel-doc package and not the kernel-doc package as distributed by RHEL.
See How to fix? for RHEL:8 relevant fixed versions and status.
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix slab-use-after-free in ext4_split_extent_at()
We hit the following use-after-free:
================================================================== BUG: KASAN: slab-use-after-free in ext4_split_extent_at+0xba8/0xcc0 Read of size 2 at addr ffff88810548ed08 by task kworker/u20:0/40 CPU: 0 PID: 40 Comm: kworker/u20:0 Not tainted 6.9.0-dirty #724 Call Trace: <TASK> kasan_report+0x93/0xc0 ext4_split_extent_at+0xba8/0xcc0 ext4_split_extent.isra.0+0x18f/0x500 ext4_split_convert_extents+0x275/0x750 ext4_ext_handle_unwritten_extents+0x73e/0x1580 ext4_ext_map_blocks+0xe20/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...]
Allocated by task 40: __kmalloc_noprof+0x1ac/0x480 ext4_find_extent+0xf3b/0x1e70 ext4_ext_map_blocks+0x188/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...]
Freed by task 40: kfree+0xf1/0x2b0 ext4_find_extent+0xa71/0x1e70 ext4_ext_insert_extent+0xa22/0x3260 ext4_split_extent_at+0x3ef/0xcc0 ext4_split_extent.isra.0+0x18f/0x500 ext4_split_convert_extents+0x275/0x750 ext4_ext_handle_unwritten_extents+0x73e/0x1580 ext4_ext_map_blocks+0xe20/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...]
The flow of issue triggering is as follows:
ext4_split_extent_at path = *ppath ext4_ext_insert_extent(ppath) ext4_ext_create_new_leaf(ppath) ext4_find_extent(orig_path) path = *orig_path read_extent_tree_block // return -ENOMEM or -EIO ext4_free_ext_path(path) kfree(path) *orig_path = NULL a. If err is -ENOMEM: ext4_ext_dirty(path + path->p_depth) // path use-after-free !!! b. If err is -EIO and we have EXT_DEBUG defined: ext4_ext_show_leaf(path) eh = path[depth].p_hdr // path also use-after-free !!!
So when trying to zeroout or fix the extent length, call ext4_find_extent() to update the path.
In addition we use *ppath directly as an ext4_ext_show_leaf() input to avoid possible use-after-free when EXT_DEBUG is defined, and to avoid unnecessary path updates.
References
- https://access.redhat.com/security/cve/CVE-2024-49884
- https://git.kernel.org/stable/c/5d949ea75bb529ea6342e83465938a3b0ac51238
- https://git.kernel.org/stable/c/8fe117790b37c84c651e2bad9efc0e7fda73c0e3
- https://git.kernel.org/stable/c/915ac3630488af0ca194dc63b86d99802b4f6e18
- https://git.kernel.org/stable/c/a5401d4c3e2a3d25643c567d26e6de327774a2c9
- https://git.kernel.org/stable/c/c26ab35702f8cd0cdc78f96aa5856bfb77be798f
- https://git.kernel.org/stable/c/cafcc1bd62934547c76abf46c6d0d54f135006fe
- https://git.kernel.org/stable/c/e52f933598b781d291b9297e39c463536da0e185
- https://git.kernel.org/stable/c/393a46f60ea4f249dc9d496d4eb2d542f5e11ade