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CVE-2021-47119

Description

In the Linux kernel, the following vulnerability has been resolved:ext4: fix memory leak in ext4_fill_superBuffer head references must be released before calling kill_bdev();otherwise the buffer head (and its page referenced by b_data) will notbe freed by kill_bdev, and subsequently that bh will be leaked.If blocksizes differ, sb_set_blocksize() will kill current buffers andpage cache by using kill_bdev(). And then super block will be rereadagain but using correct blocksize this time. sb_set_blocksize() didn'tfully free superblock page and buffer head, and being busy, they werenot freed and instead leaked.This can easily be reproduced by calling an infinite loop of: systemctl start .mount, and systemctl stop .mount... since systemd creates a cgroup for each slice which it mounts, andthe bh leak get amplified by a dying memory cgroup that also nevergets freed, and memory consumption is much more easily noticed.

POC

Reference

No PoCs from references.

Github

- https://github.com/NaInSec/CVE-LIST