Vulnerability Details : CVE-2021-47119
In the Linux kernel, the following vulnerability has been resolved:
ext4: fix memory leak in ext4_fill_super
Buffer head references must be released before calling kill_bdev();
otherwise the buffer head (and its page referenced by b_data) will not
be freed by kill_bdev, and subsequently that bh will be leaked.
If blocksizes differ, sb_set_blocksize() will kill current buffers and
page cache by using kill_bdev(). And then super block will be reread
again but using correct blocksize this time. sb_set_blocksize() didn't
fully free superblock page and buffer head, and being busy, they were
not freed and instead leaked.
This can easily be reproduced by calling an infinite loop of:
systemctl start <ext4_on_lvm>.mount, and
systemctl stop <ext4_on_lvm>.mount
... since systemd creates a cgroup for each slice which it mounts, and
the bh leak get amplified by a dying memory cgroup that also never
gets freed, and memory consumption is much more easily noticed.
Products affected by CVE-2021-47119
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:*
- cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:*
Exploit prediction scoring system (EPSS) score for CVE-2021-47119
0.04%
Probability of exploitation activity in the next 30 days
EPSS Score History
~ 5 %
Percentile, the proportion of vulnerabilities that are scored at or less
CVSS scores for CVE-2021-47119
Base Score | Base Severity | CVSS Vector | Exploitability Score | Impact Score | Score Source | First Seen |
---|---|---|---|---|---|---|
5.5
|
MEDIUM | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H |
1.8
|
3.6
|
NIST | 2025-01-07 |
CWE ids for CVE-2021-47119
-
The product does not sufficiently track and release allocated memory after it has been used, which slowly consumes remaining memory.Assigned by: nvd@nist.gov (Primary)
References for CVE-2021-47119
-
https://git.kernel.org/stable/c/1385b23396d511d5233b8b921ac3058b3f86a5e1
ext4: fix memory leak in ext4_fill_super - kernel/git/stable/linux.git - Linux kernel stable treePatch
-
https://git.kernel.org/stable/c/01d349a481f0591230300a9171330136f9159bcd
ext4: fix memory leak in ext4_fill_super - kernel/git/stable/linux.git - Linux kernel stable treePatch
-
https://git.kernel.org/stable/c/afd09b617db3786b6ef3dc43e28fe728cfea84df
ext4: fix memory leak in ext4_fill_super - kernel/git/stable/linux.git - Linux kernel stable treePatch
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