GHSA-P385-JWG8-M683
Vulnerability from github – Published: 2026-01-13 18:31 – Updated: 2026-01-13 18:31In 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: 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.
{
"affected": [],
"aliases": [
"CVE-2025-68772"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-01-13T16:15:56Z",
"severity": null
},
"details": "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": "GHSA-p385-jwg8-m683",
"modified": "2026-01-13T18:31:03Z",
"published": "2026-01-13T18:31:03Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-68772"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0bf1a02494c7eb5bd43445de4c83c8592e02c4bf"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0df713a9c082a474c8b0bcf670edc8e98461d5a0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/10b591e7fb7cdc8c1e53e9c000dc0ef7069aaa76"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ad26bfbc085c939b5dca77ff8c14798c06d151c4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bcd0086ee5a2e88c1224ff2ec1e4a43c83efe5a0"
}
],
"schema_version": "1.4.0",
"severity": []
}
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