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
[...]
============================================
Analysis and contextual insights are available on OpenCVE Cloud.
No vendor fix or workaround currently provided.
Additional remediation guidance may be available on OpenCVE Cloud.
Tracking
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| Source | ID | Title |
|---|---|---|
Debian DLA |
DLA-4008-1 | linux-6.1 security update |
Debian DLA |
DLA-4075-1 | linux security update |
Ubuntu USN |
USN-7166-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7166-2 | Linux kernel (AWS) vulnerabilities |
Ubuntu USN |
USN-7166-3 | Linux kernel (HWE) vulnerabilities |
Ubuntu USN |
USN-7166-4 | Linux kernel (Xilinx ZynqMP) vulnerabilities |
Ubuntu USN |
USN-7186-1 | Linux kernel (Intel IoTG) vulnerabilities |
Ubuntu USN |
USN-7186-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7194-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7276-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7277-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7293-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7294-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7294-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7294-3 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7294-4 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7295-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7301-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7303-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7303-2 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7303-3 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7304-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7310-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7311-1 | Linux kernel vulnerabilities |
Ubuntu USN |
USN-7384-1 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7384-2 | Linux kernel (Azure) vulnerabilities |
Ubuntu USN |
USN-7385-1 | Linux kernel (IBM) vulnerabilities |
Ubuntu USN |
USN-7386-1 | Linux kernel (OEM) vulnerabilities |
Ubuntu USN |
USN-7393-1 | Linux kernel (FIPS) vulnerabilities |
Ubuntu USN |
USN-7401-1 | Linux kernel (AWS) vulnerabilities |
Ubuntu USN |
USN-7403-1 | Linux kernel (HWE) vulnerabilities |
Ubuntu USN |
USN-7413-1 | Linux kernel (IoT) vulnerabilities |
Ubuntu USN |
USN-7468-1 | Linux kernel (Azure, N-Series) vulnerabilities |
Ubuntu USN |
USN-7539-1 | Linux kernel (Raspberry Pi) vulnerabilities |
Ubuntu USN |
USN-7540-1 | Linux kernel (Raspberry Pi) vulnerabilities |
Tue, 12 May 2026 19:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Debian
Debian debian Linux |
|
| CPEs | cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:* | |
| Vendors & Products |
Debian
Debian debian Linux |
Mon, 03 Nov 2025 23:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Mon, 03 Nov 2025 21:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Wed, 14 May 2025 02:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Redhat
Redhat enterprise Linux |
|
| CPEs | cpe:/a:redhat:enterprise_linux:9 cpe:/o:redhat:enterprise_linux:9 |
|
| Vendors & Products |
Redhat
Redhat enterprise Linux |
Fri, 08 Nov 2024 16:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
|
Fri, 01 Nov 2024 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Linux
Linux linux Kernel |
|
| Weaknesses | CWE-415 | |
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| Metrics |
cvssV3_1
|
cvssV3_1
|
Tue, 22 Oct 2024 14:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
Tue, 22 Oct 2024 13:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Mon, 21 Oct 2024 18:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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 [...] ============================================ | |
| Title | ext4: fix double brelse() the buffer of the extents path | |
| References |
|
|
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-05-11T20:41:05.182Z
Reserved: 2024-10-21T12:17:06.021Z
Link: CVE-2024-49882
Updated: 2025-11-03T22:22:48.090Z
Status : Analyzed
Published: 2024-10-21T18:15:10.790
Modified: 2026-05-12T19:08:45.180
Link: CVE-2024-49882
OpenCVE Enrichment
No data.
Debian DLA
Ubuntu USN