ghsa-f3vh-8mjp-cx6c
Vulnerability from github
Published
2024-09-04 21:30
Modified
2024-10-03 18:30
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:

btrfs: do not clear page dirty inside extent_write_locked_range()

[BUG] For subpage + zoned case, the following workload can lead to rsv data leak at unmount time:

# mkfs.btrfs -f -s 4k $dev # mount $dev $mnt # fsstress -w -n 8 -d $mnt -s 1709539240 0/0: fiemap - no filename 0/1: copyrange read - no filename 0/2: write - no filename 0/3: rename - no source filename 0/4: creat f0 x:0 0 0 0/4: creat add id=0,parent=-1 0/5: writev f0[259 1 0 0 0 0] [778052,113,965] 0 0/6: ioctl(FIEMAP) f0[259 1 0 0 224 887097] [1294220,2291618343991484791,0x10000] -1 0/7: dwrite - xfsctl(XFS_IOC_DIOINFO) f0[259 1 0 0 224 887097] return 25, fallback to stat() 0/7: dwrite f0[259 1 0 0 224 887097] [696320,102400] 0 # umount $mnt

The dmesg includes the following rsv leak detection warning (all call trace skipped):

------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8653 btrfs_destroy_inode+0x1e0/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8654 btrfs_destroy_inode+0x1a8/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- ------------[ cut here ]------------ WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8660 btrfs_destroy_inode+0x1a0/0x200 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): last unmount of filesystem 1b4abba9-de34-4f07-9e7f-157cf12a18d6 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): space_info DATA has 268218368 free, is not full BTRFS info (device sda): space_info total=268435456, used=204800, pinned=0, reserved=0, may_use=12288, readonly=0 zone_unusable=0 BTRFS info (device sda): global_block_rsv: size 0 reserved 0 BTRFS info (device sda): trans_block_rsv: size 0 reserved 0 BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0 ------------[ cut here ]------------ WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs] ---[ end trace 0000000000000000 ]--- BTRFS info (device sda): space_info METADATA has 267796480 free, is not full BTRFS info (device sda): space_info total=268435456, used=131072, pinned=0, reserved=0, may_use=262144, readonly=0 zone_unusable=245760 BTRFS info (device sda): global_block_rsv: size 0 reserved 0 BTRFS info (device sda): trans_block_rsv: size 0 reserved 0 BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0 BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0

Above $dev is a tcmu-runner emulated zoned HDD, which has a max zone append size of 64K, and the system has 64K page size.

[CAUSE] I have added several trace_printk() to show the events (header skipped):

btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688 btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288 btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536 btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864

The above lines show our buffered write has dirtied 3 pages of inode 259 of root 5:

704K 768K 832K 896K I |////I/////////////////I///////////| I 756K 868K

|///| is the dirtied range using subpage bitmaps. and 'I' is the page boundary.

Meanwhile all three pages (704K, 768K, 832K) have their PageDirty flag set.

btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400

Then direct IO writ ---truncated---

Show details on source website

To clipboard 

{
  "affected": [],
  "aliases": [
    "CVE-2024-44972"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-09-04T19:15:31Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: do not clear page dirty inside extent_write_locked_range()\n\n[BUG]\nFor subpage + zoned case, the following workload can lead to rsv data\nleak at unmount time:\n\n  # mkfs.btrfs -f -s 4k $dev\n  # mount $dev $mnt\n  # fsstress -w -n 8 -d $mnt -s 1709539240\n  0/0: fiemap - no filename\n  0/1: copyrange read - no filename\n  0/2: write - no filename\n  0/3: rename - no source filename\n  0/4: creat f0 x:0 0 0\n  0/4: creat add id=0,parent=-1\n  0/5: writev f0[259 1 0 0 0 0] [778052,113,965] 0\n  0/6: ioctl(FIEMAP) f0[259 1 0 0 224 887097] [1294220,2291618343991484791,0x10000] -1\n  0/7: dwrite - xfsctl(XFS_IOC_DIOINFO) f0[259 1 0 0 224 887097] return 25, fallback to stat()\n  0/7: dwrite f0[259 1 0 0 224 887097] [696320,102400] 0\n  # umount $mnt\n\nThe dmesg includes the following rsv leak detection warning (all call\ntrace skipped):\n\n  ------------[ cut here ]------------\n  WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8653 btrfs_destroy_inode+0x1e0/0x200 [btrfs]\n  ---[ end trace 0000000000000000 ]---\n  ------------[ cut here ]------------\n  WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8654 btrfs_destroy_inode+0x1a8/0x200 [btrfs]\n  ---[ end trace 0000000000000000 ]---\n  ------------[ cut here ]------------\n  WARNING: CPU: 2 PID: 4528 at fs/btrfs/inode.c:8660 btrfs_destroy_inode+0x1a0/0x200 [btrfs]\n  ---[ end trace 0000000000000000 ]---\n  BTRFS info (device sda): last unmount of filesystem 1b4abba9-de34-4f07-9e7f-157cf12a18d6\n  ------------[ cut here ]------------\n  WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs]\n  ---[ end trace 0000000000000000 ]---\n  BTRFS info (device sda): space_info DATA has 268218368 free, is not full\n  BTRFS info (device sda): space_info total=268435456, used=204800, pinned=0, reserved=0, may_use=12288, readonly=0 zone_unusable=0\n  BTRFS info (device sda): global_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): trans_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0\n  ------------[ cut here ]------------\n  WARNING: CPU: 3 PID: 4528 at fs/btrfs/block-group.c:4434 btrfs_free_block_groups+0x338/0x500 [btrfs]\n  ---[ end trace 0000000000000000 ]---\n  BTRFS info (device sda): space_info METADATA has 267796480 free, is not full\n  BTRFS info (device sda): space_info total=268435456, used=131072, pinned=0, reserved=0, may_use=262144, readonly=0 zone_unusable=245760\n  BTRFS info (device sda): global_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): trans_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): chunk_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): delayed_block_rsv: size 0 reserved 0\n  BTRFS info (device sda): delayed_refs_rsv: size 0 reserved 0\n\nAbove $dev is a tcmu-runner emulated zoned HDD, which has a max zone\nappend size of 64K, and the system has 64K page size.\n\n[CAUSE]\nI have added several trace_printk() to show the events (header skipped):\n\n  \u003e btrfs_dirty_pages: r/i=5/259 dirty start=774144 len=114688\n  \u003e btrfs_dirty_pages: r/i=5/259 dirty part of page=720896 off_in_page=53248 len_in_page=12288\n  \u003e btrfs_dirty_pages: r/i=5/259 dirty part of page=786432 off_in_page=0 len_in_page=65536\n  \u003e btrfs_dirty_pages: r/i=5/259 dirty part of page=851968 off_in_page=0 len_in_page=36864\n\nThe above lines show our buffered write has dirtied 3 pages of inode\n259 of root 5:\n\n  704K             768K              832K              896K\n  I           |////I/////////////////I///////////|     I\n              756K                               868K\n\n  |///| is the dirtied range using subpage bitmaps. and \u0027I\u0027 is the page\n  boundary.\n\n  Meanwhile all three pages (704K, 768K, 832K) have their PageDirty\n  flag set.\n\n  \u003e btrfs_direct_write: r/i=5/259 start dio filepos=696320 len=102400\n\nThen direct IO writ\n---truncated---",
  "id": "GHSA-f3vh-8mjp-cx6c",
  "modified": "2024-10-03T18:30:35Z",
  "published": "2024-09-04T21:30:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-44972"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/97713b1a2ced1e4a2a6c40045903797ebd44d7e0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ba4dedb71356638d8284e34724daca944be70368"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d3b403209f767e5857c1b9fda66726e6e6ffc99f"
    }
  ],
  "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"
    }
  ]
}


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