Huawei EulerOS: CVE-2024-49882: kernel security update

Huawei EulerOS: CVE-2024-49882: kernel security update

Severity

7

CVSS

(AV:L/AC:L/Au:S/C:C/I:C/A:C)

Published

10/21/2024

Created

01/15/2025

Added

01/14/2025

Modified

01/28/2025

Description

In the Linux kernel, the following vulnerability has been resolved: ext4: fix double brelse() the buffer of the extents path In ext4_ext_try_to_merge_up(), set path[1].p_bh to NULL after it has been released, otherwise it may be released twice. An example of what triggers this is as follows: split2mapsplit1 |--------|-------|--------| ext4_ext_map_blocks ext4_ext_handle_unwritten_extents ext4_split_convert_extents // path->p_depth == 0 ext4_split_extent // 1. do split1 ext4_split_extent_at |ext4_ext_insert_extent |ext4_ext_create_new_leaf |ext4_ext_grow_indepth |le16_add_cpu(&neh->eh_depth, 1) |ext4_find_extent |// return -ENOMEM |// get error and try zeroout |path = ext4_find_extent |path->p_depth = 1 |ext4_ext_try_to_merge |ext4_ext_try_to_merge_up |path->p_depth = 0 |brelse(path[1].p_bh)---> not set to NULL here |// zeroout success // 2. update path ext4_find_extent // 3. do split2 ext4_split_extent_at ext4_ext_insert_extent ext4_ext_create_new_leaf ext4_ext_grow_indepth le16_add_cpu(&neh->eh_depth, 1) ext4_find_extent path[0].p_bh = NULL; path->p_depth = 1 read_extent_tree_block---> return err // path[1].p_bh is still the old value ext4_free_ext_path ext4_ext_drop_refs // path->p_depth == 1 brelse(path[1].p_bh)---> brelse a buffer twice Finally got the following WARRNING when removing the buffer from lru: ============================================ VFS: brelse: Trying to free free buffer WARNING: CPU: 2 PID: 72 at fs/buffer.c:1241 __brelse+0x58/0x90 CPU: 2 PID: 72 Comm: kworker/u19:1 Not tainted 6.9.0-dirty #716 RIP: 0010:__brelse+0x58/0x90 Call Trace: <TASK> __find_get_block+0x6e7/0x810 bdev_getblk+0x2b/0x480 __ext4_get_inode_loc+0x48a/0x1240 ext4_get_inode_loc+0xb2/0x150 ext4_reserve_inode_write+0xb7/0x230 __ext4_mark_inode_dirty+0x144/0x6a0 ext4_ext_insert_extent+0x9c8/0x3230 ext4_ext_map_blocks+0xf45/0x2dc0 ext4_map_blocks+0x724/0x1700 ext4_do_writepages+0x12d6/0x2a70 [...] ============================================

Solution(s)

• huawei-euleros-2_0_sp10-upgrade-kernel
• huawei-euleros-2_0_sp10-upgrade-kernel-abi-stablelists
• huawei-euleros-2_0_sp10-upgrade-kernel-tools
• huawei-euleros-2_0_sp10-upgrade-kernel-tools-libs
• huawei-euleros-2_0_sp10-upgrade-python3-perf

References

• https://attackerkb.com/topics/cve-2024-49882
• CVE - 2024-49882
• EulerOS-SA-2025-1024