fkie_cve-2025-68264
Vulnerability from fkie_nvd
Published
2025-12-16 15:15
Modified
2025-12-18 15:08
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: refresh inline data size before write operations The cached ei->i_inline_size can become stale between the initial size check and when ext4_update_inline_data()/ext4_create_inline_data() use it. Although ext4_get_max_inline_size() reads the correct value at the time of the check, concurrent xattr operations can modify i_inline_size before ext4_write_lock_xattr() is acquired. This causes ext4_update_inline_data() and ext4_create_inline_data() to work with stale capacity values, leading to a BUG_ON() crash in ext4_write_inline_data(): kernel BUG at fs/ext4/inline.c:1331! BUG_ON(pos + len > EXT4_I(inode)->i_inline_size); The race window: 1. ext4_get_max_inline_size() reads i_inline_size = 60 (correct) 2. Size check passes for 50-byte write 3. [Another thread adds xattr, i_inline_size changes to 40] 4. ext4_write_lock_xattr() acquires lock 5. ext4_update_inline_data() uses stale i_inline_size = 60 6. Attempts to write 50 bytes but only 40 bytes actually available 7. BUG_ON() triggers Fix this by recalculating i_inline_size via ext4_find_inline_data_nolock() immediately after acquiring xattr_sem. This ensures ext4_update_inline_data() and ext4_create_inline_data() work with current values that are protected from concurrent modifications. This is similar to commit a54c4613dac1 ("ext4: fix race writing to an inline_data file while its xattrs are changing") which fixed i_inline_off staleness. This patch addresses the related i_inline_size staleness issue.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/210ac60a86a3ad2c76ae60e0dc71c34af6e7ea0b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/58df743faf21ceb1880f930aa5dd428e2a5e415d
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/892e1cf17555735e9d021ab036c36bc7b58b0e3b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ca43ea29b4c4d2764aec8a26cffcfb677a871e6e
Impacted products
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: refresh inline data size before write operations\n\nThe cached ei-\u003ei_inline_size can become stale between the initial size\ncheck and when ext4_update_inline_data()/ext4_create_inline_data() use\nit. Although ext4_get_max_inline_size() reads the correct value at the\ntime of the check, concurrent xattr operations can modify i_inline_size\nbefore ext4_write_lock_xattr() is acquired.\n\nThis causes ext4_update_inline_data() and ext4_create_inline_data() to\nwork with stale capacity values, leading to a BUG_ON() crash in\next4_write_inline_data():\n\n  kernel BUG at fs/ext4/inline.c:1331!\n  BUG_ON(pos + len \u003e EXT4_I(inode)-\u003ei_inline_size);\n\nThe race window:\n1. ext4_get_max_inline_size() reads i_inline_size = 60 (correct)\n2. Size check passes for 50-byte write\n3. [Another thread adds xattr, i_inline_size changes to 40]\n4. ext4_write_lock_xattr() acquires lock\n5. ext4_update_inline_data() uses stale i_inline_size = 60\n6. Attempts to write 50 bytes but only 40 bytes actually available\n7. BUG_ON() triggers\n\nFix this by recalculating i_inline_size via ext4_find_inline_data_nolock()\nimmediately after acquiring xattr_sem. This ensures ext4_update_inline_data()\nand ext4_create_inline_data() work with current values that are protected\nfrom concurrent modifications.\n\nThis is similar to commit a54c4613dac1 (\"ext4: fix race writing to an\ninline_data file while its xattrs are changing\") which fixed i_inline_off\nstaleness. This patch addresses the related i_inline_size staleness issue."
    }
  ],
  "id": "CVE-2025-68264",
  "lastModified": "2025-12-18T15:08:06.237",
  "metrics": {},
  "published": "2025-12-16T15:15:55.920",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/210ac60a86a3ad2c76ae60e0dc71c34af6e7ea0b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/58df743faf21ceb1880f930aa5dd428e2a5e415d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/892e1cf17555735e9d021ab036c36bc7b58b0e3b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ca43ea29b4c4d2764aec8a26cffcfb677a871e6e"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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