ghsa-r75j-q9wj-xrc3
Vulnerability from github
Published
2024-10-21 21:30
Modified
2024-10-28 18:31
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:

ext4: dax: fix overflowing extents beyond inode size when partially writing

The dax_iomap_rw() does two things in each iteration: map written blocks and copy user data to blocks. If the process is killed by user(See signal handling in dax_iomap_iter()), the copied data will be returned and added on inode size, which means that the length of written extents may exceed the inode size, then fsck will fail. An example is given as:

dd if=/dev/urandom of=file bs=4M count=1 dax_iomap_rw iomap_iter // round 1 ext4_iomap_begin ext4_iomap_alloc // allocate 0~2M extents(written flag) dax_iomap_iter // copy 2M data iomap_iter // round 2 iomap_iter_advance iter->pos += iter->processed // iter->pos = 2M ext4_iomap_begin ext4_iomap_alloc // allocate 2~4M extents(written flag) dax_iomap_iter fatal_signal_pending done = iter->pos - iocb->ki_pos // done = 2M ext4_handle_inode_extension ext4_update_inode_size // inode size = 2M

fsck reports: Inode 13, i_size is 2097152, should be 4194304. Fix?

Fix the problem by truncating extents if the written length is smaller than expected.

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{
   affected: [],
   aliases: [
      "CVE-2024-50015",
   ],
   database_specific: {
      cwe_ids: [],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-10-21T19:15:04Z",
      severity: "MODERATE",
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\next4: dax: fix overflowing extents beyond inode size when partially writing\n\nThe dax_iomap_rw() does two things in each iteration: map written blocks\nand copy user data to blocks. If the process is killed by user(See signal\nhandling in dax_iomap_iter()), the copied data will be returned and added\non inode size, which means that the length of written extents may exceed\nthe inode size, then fsck will fail. An example is given as:\n\ndd if=/dev/urandom of=file bs=4M count=1\n dax_iomap_rw\n  iomap_iter // round 1\n   ext4_iomap_begin\n    ext4_iomap_alloc // allocate 0~2M extents(written flag)\n  dax_iomap_iter // copy 2M data\n  iomap_iter // round 2\n   iomap_iter_advance\n    iter->pos += iter->processed // iter->pos = 2M\n   ext4_iomap_begin\n    ext4_iomap_alloc // allocate 2~4M extents(written flag)\n  dax_iomap_iter\n   fatal_signal_pending\n  done = iter->pos - iocb->ki_pos // done = 2M\n ext4_handle_inode_extension\n  ext4_update_inode_size // inode size = 2M\n\nfsck reports: Inode 13, i_size is 2097152, should be 4194304.  Fix?\n\nFix the problem by truncating extents if the written length is smaller\nthan expected.",
   id: "GHSA-r75j-q9wj-xrc3",
   modified: "2024-10-28T18:31:40Z",
   published: "2024-10-21T21:30:50Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-50015",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/5efccdee4a7d507a483f20f880b809cc4eaef14d",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/8c30a9a8610c314554997f86370140746aa35661",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/a9f331f51515bdb3ebc8d0963131af367ef468f6",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/abfaa876b948baaea4d14f21a1963789845c8b4c",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/dda898d7ffe85931f9cca6d702a51f33717c501e",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/ec0dd451e236c46e4858d53e9e82bae7797a7af5",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/f8a7c342326f6ad1dfdb30a18dd013c70f5e9669",
      },
   ],
   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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