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.
Find out more about CVE-2024-49884 from the MITRE-CVE dictionary and NIST NVD
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| Product Name | Status | Defect | Fixed | Downloads |
|---|---|---|---|---|
| Linux | ||||
| Wind River Linux LTS 17 | Requires LTSS | -- | -- | -- |
| Wind River Linux 8 | Requires LTSS | -- | -- | -- |
| Wind River Linux 9 | Requires LTSS | -- | -- | -- |
| Wind River Linux 7 | Requires LTSS | -- | -- | -- |
| Wind River Linux LTS 21 | Investigate | -- | -- | -- |
| Wind River Linux LTS 22 | Not Vulnerable | -- | -- | -- |
| Wind River Linux LTS 18 | Requires LTSS | -- | -- | -- |
| Wind River Linux LTS 19 | Investigate | -- | -- | -- |
| Wind River Linux CD release | N/A | -- | -- | -- |
| Wind River Linux 6 | Requires LTSS | -- | -- | -- |
| Wind River Linux LTS 23 | Not Vulnerable | -- | -- | -- |
| Wind River Linux LTS 24 | Not Vulnerable | -- | -- | -- |
| VxWorks | ||||
| VxWorks 7 | Not Vulnerable | -- | -- | -- |
| VxWorks 6.9 | Not Vulnerable | -- | -- | -- |
| Helix Virtualization Platform Cert Edition | ||||
| Helix Virtualization Platform Cert Edition | Not Vulnerable | -- | -- | -- |
| eLxr | ||||
| eLxr 12 | Vulnerable | -- | -- | -- |
| Product Name | Status | Defect | Fixed | Downloads |
|---|
