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CVE-2024-49884

ext4: fix slab-use-after-free in ext4_split_extent_at()

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 4.19.323, 5.4.290, 5.10.227, 5.15.168, 6.1.113, and 3 more
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

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.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • Linux Linux

    From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in 393a46f60ea4f249dc9d496d4eb2d542f5e11ade; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in 448100a29395b0c8b4c42967155849fe0fbe808f; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in e52f933598b781d291b9297e39c463536da0e185; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in cafcc1bd62934547c76abf46c6d0d54f135006fe; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in a5401d4c3e2a3d25643c567d26e6de327774a2c9; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in 8fe117790b37c84c651e2bad9efc0e7fda73c0e3; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in 5d949ea75bb529ea6342e83465938a3b0ac51238; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in 915ac3630488af0ca194dc63b86d99802b4f6e18; From dfe5080939ea4686b3414b5d970a9b26733c57a4 · fixed in c26ab35702f8cd0cdc78f96aa5856bfb77be798f

  • Linux Linux

    3.18

  • KernelLinux

    From 3.18.0 · fixed in 4.19.323; From 4.20.0 · fixed in 5.4.290; From 5.5.0 · fixed in 5.10.227; From 5.11.0 · fixed in 5.15.168; From 5.16.0 · fixed in 6.1.113; From 6.2.0 · fixed in 6.6.55; From 6.7.0 · fixed in 6.10.14; From 6.11.0 · fixed in 6.11.3

References 9

git.kernel.org