FKIE_CVE-2025-68772

Vulnerability from fkie_nvd - Published: 2026-01-13 16:15 - Updated: 2026-01-14 16:26
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: fix to avoid updating compression context during writeback Bai, Shuangpeng <sjb7183@psu.edu> reported a bug as below: Oops: divide error: 0000 [#1] SMP KASAN PTI CPU: 0 UID: 0 PID: 11441 Comm: syz.0.46 Not tainted 6.17.0 #1 PREEMPT(full) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:f2fs_all_cluster_page_ready+0x106/0x550 fs/f2fs/compress.c:857 Call Trace: <TASK> f2fs_write_cache_pages fs/f2fs/data.c:3078 [inline] __f2fs_write_data_pages fs/f2fs/data.c:3290 [inline] f2fs_write_data_pages+0x1c19/0x3600 fs/f2fs/data.c:3317 do_writepages+0x38e/0x640 mm/page-writeback.c:2634 filemap_fdatawrite_wbc mm/filemap.c:386 [inline] __filemap_fdatawrite_range mm/filemap.c:419 [inline] file_write_and_wait_range+0x2ba/0x3e0 mm/filemap.c:794 f2fs_do_sync_file+0x6e6/0x1b00 fs/f2fs/file.c:294 generic_write_sync include/linux/fs.h:3043 [inline] f2fs_file_write_iter+0x76e/0x2700 fs/f2fs/file.c:5259 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x7e9/0xe00 fs/read_write.c:686 ksys_write+0x19d/0x2d0 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xf7/0x470 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f The bug was triggered w/ below race condition: fsync setattr ioctl - f2fs_do_sync_file - file_write_and_wait_range - f2fs_write_cache_pages : inode is non-compressed : cc.cluster_size = F2FS_I(inode)->i_cluster_size = 0 - tag_pages_for_writeback - f2fs_setattr - truncate_setsize - f2fs_truncate - f2fs_fileattr_set - f2fs_setflags_common - set_compress_context : F2FS_I(inode)->i_cluster_size = 4 : set_inode_flag(inode, FI_COMPRESSED_FILE) - f2fs_compressed_file : return true - f2fs_all_cluster_page_ready : "pgidx % cc->cluster_size" trigger dividing 0 issue Let's change as below to fix this issue: - introduce a new atomic type variable .writeback in structure f2fs_inode_info to track the number of threads which calling f2fs_write_cache_pages(). - use .i_sem lock to protect .writeback update. - check .writeback before update compression context in f2fs_setflags_common() to avoid race w/ ->writepages.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0bf1a02494c7eb5bd43445de4c83c8592e02c4bf
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0df713a9c082a474c8b0bcf670edc8e98461d5a0
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/10b591e7fb7cdc8c1e53e9c000dc0ef7069aaa76
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ad26bfbc085c939b5dca77ff8c14798c06d151c4
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/bcd0086ee5a2e88c1224ff2ec1e4a43c83efe5a0
Impacted products
Vendor Product Version
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{
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nf2fs: fix to avoid updating compression context during writeback\n\nBai, Shuangpeng \u003csjb7183@psu.edu\u003e reported a bug as below:\n\nOops: divide error: 0000 [#1] SMP KASAN PTI\nCPU: 0 UID: 0 PID: 11441 Comm: syz.0.46 Not tainted 6.17.0 #1 PREEMPT(full)\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014\nRIP: 0010:f2fs_all_cluster_page_ready+0x106/0x550 fs/f2fs/compress.c:857\nCall Trace:\n \u003cTASK\u003e\n f2fs_write_cache_pages fs/f2fs/data.c:3078 [inline]\n __f2fs_write_data_pages fs/f2fs/data.c:3290 [inline]\n f2fs_write_data_pages+0x1c19/0x3600 fs/f2fs/data.c:3317\n do_writepages+0x38e/0x640 mm/page-writeback.c:2634\n filemap_fdatawrite_wbc mm/filemap.c:386 [inline]\n __filemap_fdatawrite_range mm/filemap.c:419 [inline]\n file_write_and_wait_range+0x2ba/0x3e0 mm/filemap.c:794\n f2fs_do_sync_file+0x6e6/0x1b00 fs/f2fs/file.c:294\n generic_write_sync include/linux/fs.h:3043 [inline]\n f2fs_file_write_iter+0x76e/0x2700 fs/f2fs/file.c:5259\n new_sync_write fs/read_write.c:593 [inline]\n vfs_write+0x7e9/0xe00 fs/read_write.c:686\n ksys_write+0x19d/0x2d0 fs/read_write.c:738\n do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]\n do_syscall_64+0xf7/0x470 arch/x86/entry/syscall_64.c:94\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\n\nThe bug was triggered w/ below race condition:\n\nfsync\t\t\t\tsetattr\t\t\tioctl\n- f2fs_do_sync_file\n - file_write_and_wait_range\n  - f2fs_write_cache_pages\n  : inode is non-compressed\n  : cc.cluster_size =\n    F2FS_I(inode)-\u003ei_cluster_size = 0\n   - tag_pages_for_writeback\n\t\t\t\t- f2fs_setattr\n\t\t\t\t - truncate_setsize\n\t\t\t\t - f2fs_truncate\n\t\t\t\t\t\t\t- f2fs_fileattr_set\n\t\t\t\t\t\t\t - f2fs_setflags_common\n\t\t\t\t\t\t\t  - set_compress_context\n\t\t\t\t\t\t\t  : F2FS_I(inode)-\u003ei_cluster_size = 4\n\t\t\t\t\t\t\t  : set_inode_flag(inode, FI_COMPRESSED_FILE)\n   - f2fs_compressed_file\n   : return true\n   - f2fs_all_cluster_page_ready\n   : \"pgidx % cc-\u003ecluster_size\" trigger dividing 0 issue\n\nLet\u0027s change as below to fix this issue:\n- introduce a new atomic type variable .writeback in structure f2fs_inode_info\nto track the number of threads which calling f2fs_write_cache_pages().\n- use .i_sem lock to protect .writeback update.\n- check .writeback before update compression context in f2fs_setflags_common()\nto avoid race w/ -\u003ewritepages."
    }
  ],
  "id": "CVE-2025-68772",
  "lastModified": "2026-01-14T16:26:00.933",
  "metrics": {},
  "published": "2026-01-13T16:15:56.707",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0bf1a02494c7eb5bd43445de4c83c8592e02c4bf"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/0df713a9c082a474c8b0bcf670edc8e98461d5a0"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/10b591e7fb7cdc8c1e53e9c000dc0ef7069aaa76"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/ad26bfbc085c939b5dca77ff8c14798c06d151c4"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/bcd0086ee5a2e88c1224ff2ec1e4a43c83efe5a0"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}


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