CVE-2021-47119 — ext4: fix memory leak in ext4_fill_super

Affected: Linux

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.

USN-7415-1 — linux vulnerabilities

Affected: Ubuntu:Pro:14.04:LTS: linux

Several security issues were discovered in the Linux kernel. An attacker could possibly use these to compromise the system. This update corrects flaws in the following subsystems: - Drivers core; - Ext4 file system; - JFS file system; - Network namespace; - CAIF protocol; - Networking core; - IPv6 networking; (CVE-2024-56658, CVE-2021-47119, CVE-2024-56600, CVE-2021-47122, CVE-2021-47483, CVE-2024-56595)

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CVE-2021-47119 — ext4: fix memory leak in ext4_fill_super

USN-7415-1 — linux vulnerabilities