CVE - CVE-2024-49882

CVE-ID
CVE-2024-49882	Learn more at National Vulnerability Database (NVD) • CVSS Severity Rating • Fix Information • Vulnerable Software Versions • SCAP Mappings • CPE Information
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: split2 map split1 \|--------\|-------\|--------\| 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 [...] ============================================
References
Note: References are provided for the convenience of the reader to help distinguish between vulnerabilities. The list is not intended to be complete.
MISC:https://git.kernel.org/stable/c/230ee0535d01478bad9a3037292043f39b9be10b URL:https://git.kernel.org/stable/c/230ee0535d01478bad9a3037292043f39b9be10b MISC:https://git.kernel.org/stable/c/32bbb59e3f18facd7201bef110010bf35819b8c3 URL:https://git.kernel.org/stable/c/32bbb59e3f18facd7201bef110010bf35819b8c3 MISC:https://git.kernel.org/stable/c/68a69cf60660c73990c1875f94a5551600b04775 URL:https://git.kernel.org/stable/c/68a69cf60660c73990c1875f94a5551600b04775 MISC:https://git.kernel.org/stable/c/7633407ca4ab8be2916ab214eb44ccebc6a50e1a URL:https://git.kernel.org/stable/c/7633407ca4ab8be2916ab214eb44ccebc6a50e1a MISC:https://git.kernel.org/stable/c/78bbc3d15b6f443acb26e94418c445bac940d414 URL:https://git.kernel.org/stable/c/78bbc3d15b6f443acb26e94418c445bac940d414 MISC:https://git.kernel.org/stable/c/b6c29c8f3d7cb67b505f3b2f6c242d52298d1f2e URL:https://git.kernel.org/stable/c/b6c29c8f3d7cb67b505f3b2f6c242d52298d1f2e MISC:https://git.kernel.org/stable/c/dcaa6c31134c0f515600111c38ed7750003e1b9c URL:https://git.kernel.org/stable/c/dcaa6c31134c0f515600111c38ed7750003e1b9c
Assigning CNA
kernel.org
Date Record Created
20241021	Disclaimer: The record creation date may reflect when the CVE ID was allocated or reserved, and does not necessarily indicate when this vulnerability was discovered, shared with the affected vendor, publicly disclosed, or updated in CVE.
Phase (Legacy)
Assigned (20241021)
Votes (Legacy)

Comments (Legacy)

Proposed (Legacy)
N/A
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