In the Linux kernel, the following vulnerability has been resolved:
ext4: allow ext4_get_group_info() to fail
Previously, ext4_get_group_info() would treat an invalid group number
as BUG(), since in theory it should never happen. However, if a
malicious attaker (or fuzzer) modifies the superblock via the block
device while it is the file system is mounted, it is possible for
s_first_data_block to get set to a very large number. In that case,
when calculating the block group of some block number (such as the
starting block of a preallocation region), could result in an
underflow and very large block group number. Then the BUG_ON check in
ext4_get_group_info() would fire, resutling in a denial of service
attack that can be triggered by root or someone with write access to
the block device.
For a quality of implementation perspective, it's best that even if
the system administrator does something that they shouldn't, that it
will not trigger a BUG. So instead of BUG'ing, ext4_get_group_info()
will call ext4_error and return NULL. We also add fallback code in
all of the callers of ext4_get_group_info() that it might NULL.
Also, since ext4_get_group_info() was already borderline to be an
inline function, un-inline it. The results in a next reduction of the
compiled text size of ext4 by roughly 2k.
References
Configurations
Configuration 1 (hide)
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History
26 Jan 2026, 19:52
| Type | Values Removed | Values Added |
|---|---|---|
| References | () https://git.kernel.org/stable/c/100c0ad6c04597fefeaaba2bb1827cc015d95067 - Patch | |
| References | () https://git.kernel.org/stable/c/31668cebf45adfb6283e465e641c4f5a21b07afa - Patch | |
| References | () https://git.kernel.org/stable/c/5354b2af34064a4579be8bc0e2f15a7b70f14b5f - Patch | |
| References | () https://git.kernel.org/stable/c/620a3c28221bb219b81bc0bffd065cc187494302 - Patch | |
| References | () https://git.kernel.org/stable/c/b4319e457d6e3fb33e443efeaf4634fc36e8a9ed - Patch | |
| CVSS |
v2 : v3 : |
v2 : unknown
v3 : 5.5 |
| CWE | CWE-476 | |
| First Time |
Linux
Linux linux Kernel |
|
| CPE | cpe:2.3:o:linux:linux_kernel:6.4:rc1:*:*:*:*:*:* cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* |
01 Oct 2025, 12:15
| Type | Values Removed | Values Added |
|---|---|---|
| New CVE |
Information
Published : 2025-10-01 12:15
Updated : 2026-01-26 19:52
NVD link : CVE-2023-53503
Mitre link : CVE-2023-53503
CVE.ORG link : CVE-2023-53503
JSON object : View
Products Affected
linux
- linux_kernel
CWE
CWE-476
NULL Pointer Dereference