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THREATINT
PUBLISHED

CVE-2024-47680

f2fs: check discard support for conventional zones



AssignerLinux
Reserved2024-09-30
Published2024-10-21
Updated2024-11-05

Description

In the Linux kernel, the following vulnerability has been resolved: f2fs: check discard support for conventional zones As the helper function f2fs_bdev_support_discard() shows, f2fs checks if the target block devices support discard by calling bdev_max_discard_sectors() and bdev_is_zoned(). This check works well for most cases, but it does not work for conventional zones on zoned block devices. F2fs assumes that zoned block devices support discard, and calls __submit_discard_cmd(). When __submit_discard_cmd() is called for sequential write required zones, it works fine since __submit_discard_cmd() issues zone reset commands instead of discard commands. However, when __submit_discard_cmd() is called for conventional zones, __blkdev_issue_discard() is called even when the devices do not support discard. The inappropriate __blkdev_issue_discard() call was not a problem before the commit 30f1e7241422 ("block: move discard checks into the ioctl handler") because __blkdev_issue_discard() checked if the target devices support discard or not. If not, it returned EOPNOTSUPP. After the commit, __blkdev_issue_discard() no longer checks it. It always returns zero and sets NULL to the given bio pointer. This NULL pointer triggers f2fs_bug_on() in __submit_discard_cmd(). The BUG is recreated with the commands below at the umount step, where /dev/nullb0 is a zoned null_blk with 5GB total size, 128MB zone size and 10 conventional zones. $ mkfs.f2fs -f -m /dev/nullb0 $ mount /dev/nullb0 /mnt $ for ((i=0;i<5;i++)); do dd if=/dev/zero of=/mnt/test bs=65536 count=1600 conv=fsync; done $ umount /mnt To fix the BUG, avoid the inappropriate __blkdev_issue_discard() call. When discard is requested for conventional zones, check if the device supports discard or not. If not, return EOPNOTSUPP.

Product status

Default status
unaffected

30f1e7241422 before 7bd7ce68ddad
affected

30f1e7241422 before d2352b57897f
affected

30f1e7241422 before 43aec4d01bd2
affected

Default status
affected

6.10
affected

Any version before 6.10
unaffected

6.10.13
unaffected

6.11.2
unaffected

6.12-rc1
unaffected

References

https://git.kernel.org/stable/c/7bd7ce68ddad5a28565e42ef21cacaff113773a9

https://git.kernel.org/stable/c/d2352b57897f6a3349666fc318dcbec99092c6a5

https://git.kernel.org/stable/c/43aec4d01bd2ce961817a777b3846f8318f398e4

cve.org CVE-2024-47680

nvd.nist.gov CVE-2024-47680

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