KMSAN: uninit-value in xlog_sync

Status: upstream: reported on 2026/01/08 02:14
Subsystems: xfs
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+97f2c05378c5d68dcb8c@syzkaller.appspotmail.com
First crash: 206d, last: 51d
▶ ▼ ✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision Error
28ec2f9b assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ✅ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ ❓ KMSAN: uninit-value in xlog_sync 2026/05/30 19:04 2026/05/30 19:04 2026/05/30 19:43 6b4a8443 

			
				
	

	
	

		ec04954e
		assessment-security
		
			
		
		💥
		KMSAN: uninit-value in xlog_sync
		2026/05/14 11:33
		2026/05/14 11:33
		2026/05/14 11:34
		6ccb967e
		
			
failed to run ["git" "pull" "origin" "HEAD" "--depth=1" "--allow-unrelated-histories"]: exit status 128
From /app/workdir/repo/linux
 * branch                HEAD       -> FETCH_HEAD
Updating files:  ...

			
				
truncated to first 200 bytes; open job for full error

			
				
	

	
	

		ae25e52d
		repro
		
			
				
			
				
			
				
			
		
		❓
		KMSAN: uninit-value in xlog_sync
		2026/03/06 14:52
		2026/03/06 14:52
		2026/03/06 15:02
		31e9c887
		
			

			
				
	

	
	



			

		

	

	
	

		

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			Discussions (4)
		

		

			
			
			



	
	

		Title
		Replies (including bot)
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			[PATCH v2] xfs: zero newly allocated btree root space
			3 (3)
			2026/06/30 20:39
		

	
		

			[PATCH] xfs: zero newly allocated btree root space
			3 (3)
			2026/06/30 10:01
		

	
		

			[syzbot] Monthly xfs report (Jun 2026)
			0 (1)
			2026/06/11 12:32
		

	
		

			[syzbot] [xfs?] KMSAN: uninit-value in xlog_sync
			0 (1)
			2026/01/08 02:14
		

	
	




			
			
		

	

	

	
	
Sample crash report:

	
=====================================================
BUG: KMSAN: uninit-value in crc32c_arch lib/crc/x86/crc32.h:90 [inline]
BUG: KMSAN: uninit-value in crc32c+0x131/0x540 lib/crc/crc32-main.c:86
 crc32c_arch lib/crc/x86/crc32.h:90 [inline]
 crc32c+0x131/0x540 lib/crc/crc32-main.c:86
 xfs_start_cksum_update fs/xfs/libxfs/xfs_cksum.h:41 [inline]
 xlog_cksum fs/xfs/xfs_log.c:1513 [inline]
 xlog_sync+0x924/0xdb0 fs/xfs/xfs_log.c:1751
 xlog_state_release_iclog+0x30b/0x6d0 fs/xfs/xfs_log.c:518
 xlog_force_iclog fs/xfs/xfs_log.c:753 [inline]
 xlog_force_and_check_iclog fs/xfs/xfs_log.c:2751 [inline]
 xlog_force_lsn+0x8eb/0xbc0 fs/xfs/xfs_log.c:2923
 xfs_log_force_seq+0x236/0x6d0 fs/xfs/xfs_log.c:2988
 xfs_fsync_flush_log fs/xfs/xfs_file.c:120 [inline]
 xfs_file_fsync+0x68e/0xe00 fs/xfs/xfs_file.c:163
 vfs_fsync_range+0x135/0x1c0 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2654 [inline]
 iomap_dio_complete+0xf01/0x13a0 fs/iomap/direct-io.c:152
 iomap_dio_rw+0x13c/0x180 fs/iomap/direct-io.c:905
 xfs_file_dio_write_aligned+0x506/0x840 fs/xfs/xfs_file.c:780
 xfs_file_dio_write fs/xfs/xfs_file.c:989 [inline]
 xfs_file_write_iter+0xff0/0x1090 fs/xfs/xfs_file.c:1201
 iter_file_splice_write+0x12d8/0x20c0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x31a/0x7d0 fs/splice.c:1159
 splice_direct_to_actor+0x9a3/0x1560 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1228
 do_sendfile+0x9fc/0x1130 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x1ea/0x290 fs/read_write.c:1419
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1419
 x64_sys_call+0x3aa4/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15d/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 xlog_pack_data+0x257/0x450 fs/xfs/xfs_log.c:1487
 xlog_sync+0x175/0xdb0 fs/xfs/xfs_log.c:1733
 xlog_state_release_iclog+0x30b/0x6d0 fs/xfs/xfs_log.c:518
 xlog_force_iclog fs/xfs/xfs_log.c:753 [inline]
 xlog_force_and_check_iclog fs/xfs/xfs_log.c:2751 [inline]
 xlog_force_lsn+0x8eb/0xbc0 fs/xfs/xfs_log.c:2923
 xfs_log_force_seq+0x236/0x6d0 fs/xfs/xfs_log.c:2988
 xfs_fsync_flush_log fs/xfs/xfs_file.c:120 [inline]
 xfs_file_fsync+0x68e/0xe00 fs/xfs/xfs_file.c:163
 vfs_fsync_range+0x135/0x1c0 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2654 [inline]
 iomap_dio_complete+0xf01/0x13a0 fs/iomap/direct-io.c:152
 iomap_dio_rw+0x13c/0x180 fs/iomap/direct-io.c:905
 xfs_file_dio_write_aligned+0x506/0x840 fs/xfs/xfs_file.c:780
 xfs_file_dio_write fs/xfs/xfs_file.c:989 [inline]
 xfs_file_write_iter+0xff0/0x1090 fs/xfs/xfs_file.c:1201
 iter_file_splice_write+0x12d8/0x20c0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x31a/0x7d0 fs/splice.c:1159
 splice_direct_to_actor+0x9a3/0x1560 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1228
 do_sendfile+0x9fc/0x1130 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x1ea/0x290 fs/read_write.c:1419
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1419
 x64_sys_call+0x3aa4/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15d/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was stored to memory at:
 xlog_write_iovec fs/xfs/xfs_log.c:1913 [inline]
 xlog_write_full fs/xfs/xfs_log.c:1940 [inline]
 xlog_write+0x1a75/0x20f0 fs/xfs/xfs_log.c:2180
 xlog_cil_write_chain fs/xfs/xfs_log_cil.c:1175 [inline]
 xlog_cil_push_work+0x355c/0x5080 fs/xfs/xfs_log_cil.c:1518
 process_one_work kernel/workqueue.c:3314 [inline]
 process_scheduled_works+0xb65/0x1e40 kernel/workqueue.c:3397
 worker_thread+0xee4/0x1590 kernel/workqueue.c:3478
 kthread+0x53a/0x5f0 kernel/kthread.c:436
 ret_from_fork+0x20f/0x8d0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Uninit was stored to memory at:
 xlog_format_copy fs/xfs/xfs_log.h:78 [inline]
 xfs_inode_item_format_data_fork+0x3ba/0xc00 fs/xfs/xfs_inode_item.c:376
 xfs_inode_item_format+0x1fb4/0x2280 fs/xfs/xfs_inode_item.c:672
 xlog_cil_insert_format_items fs/xfs/xfs_log_cil.c:603 [inline]
 xlog_cil_insert_items fs/xfs/xfs_log_cil.c:654 [inline]
 xlog_cil_commit+0x18ad/0x47d0 fs/xfs/xfs_log_cil.c:1841
 __xfs_trans_commit+0x55a/0xf40 fs/xfs/xfs_trans.c:868
 xfs_trans_commit+0x227/0x270 fs/xfs/xfs_trans.c:926
 xfs_iomap_write_unwritten+0x921/0x10e0 fs/xfs/xfs_iomap.c:700
 xfs_dio_write_end_io+0x7fc/0xc40 fs/xfs/xfs_file.c:682
 iomap_dio_complete+0x183/0x13a0 fs/iomap/direct-io.c:112
 iomap_dio_rw+0x13c/0x180 fs/iomap/direct-io.c:905
 xfs_file_dio_write_aligned+0x506/0x840 fs/xfs/xfs_file.c:780
 xfs_file_dio_write fs/xfs/xfs_file.c:989 [inline]
 xfs_file_write_iter+0xff0/0x1090 fs/xfs/xfs_file.c:1201
 iter_file_splice_write+0x12d8/0x20c0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x31a/0x7d0 fs/splice.c:1159
 splice_direct_to_actor+0x9a3/0x1560 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1228
 do_sendfile+0x9fc/0x1130 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x1ea/0x290 fs/read_write.c:1419
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1419
 x64_sys_call+0x3aa4/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15d/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:4577 [inline]
 slab_alloc_node mm/slub.c:4899 [inline]
 __do_kmalloc_node mm/slub.c:5295 [inline]
 __kmalloc_node_track_caller_noprof+0x4f6/0x1750 mm/slub.c:5408
 __do_krealloc mm/slub.c:6711 [inline]
 krealloc_node_align_noprof+0x515/0xf20 mm/slub.c:6770
 xfs_broot_realloc+0x361/0x480 fs/xfs/libxfs/xfs_inode_fork.c:431
 xfs_bmap_broot_realloc+0x243/0x650 fs/xfs/libxfs/xfs_bmap_btree.c:-1
 xfs_bmap_extents_to_btree+0x1f8/0x1430 fs/xfs/libxfs/xfs_bmap.c:660
 xfs_bmap_add_extent_hole_real+0x2267/0x3040 fs/xfs/libxfs/xfs_bmap.c:2791
 xfs_bmapi_allocate+0x48d2/0x4f50 fs/xfs/libxfs/xfs_bmap.c:3977
 xfs_bmapi_write+0x10a9/0x26f0 fs/xfs/libxfs/xfs_bmap.c:4267
 xfs_iomap_write_direct+0x6f0/0xa50 fs/xfs/xfs_iomap.c:338
 xfs_direct_write_iomap_begin+0x1a37/0x2570 fs/xfs/xfs_iomap.c:1012
 iomap_iter+0x9a6/0x14a0 fs/iomap/iter.c:110
 __iomap_dio_rw+0x14e8/0x3990 fs/iomap/direct-io.c:806
 iomap_dio_rw+0x5d/0x180 fs/iomap/direct-io.c:901
 xfs_file_dio_write_aligned+0x506/0x840 fs/xfs/xfs_file.c:780
 xfs_file_dio_write fs/xfs/xfs_file.c:989 [inline]
 xfs_file_write_iter+0xff0/0x1090 fs/xfs/xfs_file.c:1201
 iter_file_splice_write+0x12d8/0x20c0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x31a/0x7d0 fs/splice.c:1159
 splice_direct_to_actor+0x9a3/0x1560 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x1e0/0x350 fs/splice.c:1228
 do_sendfile+0x9fc/0x1130 fs/read_write.c:1372
 __do_sys_sendfile64 fs/read_write.c:1433 [inline]
 __se_sys_sendfile64+0x1ea/0x290 fs/read_write.c:1419
 __x64_sys_sendfile64+0xbd/0x120 fs/read_write.c:1419
 x64_sys_call+0x3aa4/0x3ea0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15d/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

CPU: 0 UID: 0 PID: 11335 Comm: syz.7.876 Tainted: G             L      syzkaller #0 PREEMPT(lazy) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
=====================================================



	

	



	Crashes (3):
		
		

			Time
			Kernel
			Commit
			Syzkaller
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			Title
		

		
		
		
		

			2026/06/07 20:15
			upstream
			979c294509f9
			cc095639
			.config
			console log
			report
			
			
			info
			
				[disk image]
			
				[vmlinux]
			
				[kernel image]
			
			ci-upstream-kmsan-gce-root
			KMSAN: uninit-value in xlog_sync
		

		
		

			2026/03/16 04:09
			upstream
			f338e7738378
			ee8d34d6
			.config
			console log
			report
			
			
			info
			
				[disk image]
			
				[vmlinux]
			
				[kernel image]
			
			ci-upstream-kmsan-gce-root
			KMSAN: uninit-value in xlog_sync
		

		
		

			2026/01/04 02:11
			upstream
			aacb0a6d604a
			d6526ea3
			.config
			console log
			report
			
			
			info
			
				[disk image]
			
				[vmlinux]
			
				[kernel image]
			
			ci-upstream-kmsan-gce-root
			KMSAN: uninit-value in xlog_sync
		

		
		


* Struck through repros no longer work on HEAD.