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CVE PROGRAM SOURCE RECORD7.8 High

CVE-2024-49884

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

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Status
Published
Published
Updated
Assigning organization
Linux

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < 393a46f60ea4f249dc9d496d4eb2d542f5e11adeaffected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < 448100a29395b0c8b4c42967155849fe0fbe808faffected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < e52f933598b781d291b9297e39c463536da0e185affected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < cafcc1bd62934547c76abf46c6d0d54f135006feaffected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < a5401d4c3e2a3d25643c567d26e6de327774a2c9affected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < 8fe117790b37c84c651e2bad9efc0e7fda73c0e3affected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < 5d949ea75bb529ea6342e83465938a3b0ac51238affected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < 915ac3630488af0ca194dc63b86d99802b4f6e18affected
  • dfe5080939ea4686b3414b5d970a9b26733c57a4 to < c26ab35702f8cd0cdc78f96aa5856bfb77be798faffected

Linux Linux

Default version status: affected

  • 3.18affected
  • 0 to < 3.18unaffected
  • 4.19.323 to ≤ 4.19.*unaffected
  • 5.4.290 to ≤ 5.4.*unaffected
  • 5.10.227 to ≤ 5.10.*unaffected
  • 5.15.168 to ≤ 5.15.*unaffected
  • 6.1.113 to ≤ 6.1.*unaffected
  • 6.6.55 to ≤ 6.6.*unaffected
  • 6.10.14 to ≤ 6.10.*unaffected
  • 6.11.3 to ≤ 6.11.*unaffected
  • 6.12 to ≤ *unaffected

References