ghsa-2cvc-2cmj-7863
Vulnerability from github
Published
2024-10-21 12:30
Modified
2024-10-24 15:31
Severity ?
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Details

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.

Show details on source website

To clipboard 

{
   affected: [],
   aliases: [
      "CVE-2024-47680",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-476",
      ],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-10-21T12:15:05Z",
      severity: "MODERATE",
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: check discard support for conventional zones\n\nAs the helper function f2fs_bdev_support_discard() shows, f2fs checks if\nthe target block devices support discard by calling\nbdev_max_discard_sectors() and bdev_is_zoned(). This check works well\nfor most cases, but it does not work for conventional zones on zoned\nblock devices. F2fs assumes that zoned block devices support discard,\nand calls __submit_discard_cmd(). When __submit_discard_cmd() is called\nfor sequential write required zones, it works fine since\n__submit_discard_cmd() issues zone reset commands instead of discard\ncommands. However, when __submit_discard_cmd() is called for\nconventional zones, __blkdev_issue_discard() is called even when the\ndevices do not support discard.\n\nThe inappropriate __blkdev_issue_discard() call was not a problem before\nthe commit 30f1e7241422 (\"block: move discard checks into the ioctl\nhandler\") because __blkdev_issue_discard() checked if the target devices\nsupport discard or not. If not, it returned EOPNOTSUPP. After the\ncommit, __blkdev_issue_discard() no longer checks it. It always returns\nzero and sets NULL to the given bio pointer. This NULL pointer triggers\nf2fs_bug_on() in __submit_discard_cmd(). The BUG is recreated with the\ncommands below at the umount step, where /dev/nullb0 is a zoned null_blk\nwith 5GB total size, 128MB zone size and 10 conventional zones.\n\n$ mkfs.f2fs -f -m /dev/nullb0\n$ mount /dev/nullb0 /mnt\n$ for ((i=0;i<5;i++)); do dd if=/dev/zero of=/mnt/test bs=65536 count=1600 conv=fsync; done\n$ umount /mnt\n\nTo fix the BUG, avoid the inappropriate __blkdev_issue_discard() call.\nWhen discard is requested for conventional zones, check if the device\nsupports discard or not. If not, return EOPNOTSUPP.",
   id: "GHSA-2cvc-2cmj-7863",
   modified: "2024-10-24T15:31:07Z",
   published: "2024-10-21T12:30:54Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-47680",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/43aec4d01bd2ce961817a777b3846f8318f398e4",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/7bd7ce68ddad5a28565e42ef21cacaff113773a9",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/d2352b57897f6a3349666fc318dcbec99092c6a5",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
         type: "CVSS_V3",
      },
   ],
}


Log in or create an account to share your comment.

Security Advisory comment format.

This schema specifies the format of a comment related to a security advisory.

UUIDv4 of the comment
UUIDv4 of the Vulnerability-Lookup instance
When the comment was created originally
When the comment was last updated
Title of the comment
Description of the comment
The identifier of the vulnerability (CVE ID, GHSA-ID, PYSEC ID, etc.).



Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.