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Debian: CVE-2021-47119: linux -- security update

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Debian: CVE-2021-47119: linux -- security update

Severity
5
CVSS
(AV:L/AC:L/Au:S/C:N/I:N/A:C)
Published
03/15/2024
Created
07/31/2024
Added
07/30/2024
Modified
01/30/2025

Description

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.

Solution(s)

  • debian-upgrade-linux

References

  • https://attackerkb.com/topics/cve-2021-47119
  • CVE - 2021-47119
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