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KASAN: use-after-free Write in ocfs2_write_end_nolock

Status: moderation: reported on 2026/03/31 04:54
Subsystems: ocfs2
[Documentation on labels]
Reported-by: syzbot+a5706c40272f680ce461@syzkaller.appspotmail.com
First crash: 6d05h, last: 3h27m
âœĻ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
ebe1e268-331b-4095-9d1d-2456fd3ebd5e moderation Actionable: ✅  Confident: ✅  ❓ KASAN: use-after-free Write in ocfs2_write_end_nolock 2026/04/01 00:02 2026/04/01 00:02 2026/04/01 01:06 aeea1c7238ce8309f33041dd38ccef93fffa0d3c

Sample crash report:
loop0: detected capacity change from 0 to 32768
=======================================================
WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
JBD2: Ignoring recovery information on journal
ocfs2: Mounting device (7,0) on (node local, slot 0) with ordered data mode.
(syz.0.0,5322,0):ocfs2_check_set_options:1244 ERROR: Invalid heartbeat mount options
loop0: detected capacity change from 32768 to 32767
OCFS2: ERROR (device loop0): int ocfs2_validate_inode_block(struct super_block *, struct buffer_head *): Invalid dinode #17058: signature = Bąđ
On-disk corruption discovered. Please run fsck.ocfs2 once the filesystem is unmounted.
OCFS2: File system is now read-only.
(syz.0.0,5322,0):ocfs2_assign_bh:2417 ERROR: status = -30
(syz.0.0,5322,0):ocfs2_inode_lock_full_nested:2512 ERROR: status = -30
(syz.0.0,5322,0):ocfs2_reflink_inodes_lock:4748 ERROR: status = -30
==================================================================
BUG: KASAN: use-after-free in memcpy_from_folio include/linux/highmem.h:586 [inline]
BUG: KASAN: use-after-free in ocfs2_write_end_inline fs/ocfs2/aops.c:1915 [inline]
BUG: KASAN: use-after-free in ocfs2_write_end_nolock+0xbd9/0x18f0 fs/ocfs2/aops.c:1949
Write of size 4086 at addr ffff888056cb94d2 by task syz.0.0/5322

CPU: 0 UID: 0 PID: 5322 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x264/0x2c0 mm/kasan/generic.c:200
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 memcpy_from_folio include/linux/highmem.h:586 [inline]
 ocfs2_write_end_inline fs/ocfs2/aops.c:1915 [inline]
 ocfs2_write_end_nolock+0xbd9/0x18f0 fs/ocfs2/aops.c:1949
 ocfs2_write_end+0x58/0x90 fs/ocfs2/aops.c:2059
 generic_perform_write+0x620/0x8f0 mm/filemap.c:4340
 ocfs2_file_write_iter+0x1663/0x1ed0 fs/ocfs2/file.c:2476
 iter_file_splice_write+0x9a1/0x10f0 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x101/0x160 fs/splice.c:1159
 splice_direct_to_actor+0x53a/0xc70 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x195/0x290 fs/splice.c:1228
 vfs_copy_file_range+0xb02/0x1370 fs/read_write.c:1634
 __do_sys_copy_file_range fs/read_write.c:1683 [inline]
 __se_sys_copy_file_range+0x2fb/0x480 fs/read_write.c:1650
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f915939c819
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f91557f4fe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000146
RAX: ffffffffffffffda RBX: 00007f9159615fa0 RCX: 00007f915939c819
RDX: 0000000000000006 RSI: 00002000000001c0 RDI: 0000000000000007
RBP: 00007f9159432c91 R08: ffffffffa003e45b R09: 0700000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f9159616038 R14: 00007f9159615fa0 R15: 00007ffd910843b8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:2 mapcount:0 mapping:ffff88801cc2e6c8 index:0x854 pfn:0x56cb9
memcg:ffff88801c6c0d40
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0x4fff38000004224(referenced|lru|workingset|private|node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff38000004224 ffffea0000daa148 ffff8880304509e0 ffff88801cc2e6c8
raw: 0000000000000854 ffff888047a7f488 00000002ffffffff ffff88801c6c0d40
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_MOVABLE|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL), pid 5322, tgid 5321 (syz.0.0), ts 84481666302, free_ts 84442966008
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x24dc/0x2580 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2490
 alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
 alloc_pages_noprof+0xa8/0x1a0 mm/mempolicy.c:2581
 folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2591
 filemap_alloc_folio_noprof+0x111/0x470 mm/filemap.c:1013
 __filemap_get_folio_mpol+0x3fc/0xb00 mm/filemap.c:2011
 __filemap_get_folio include/linux/pagemap.h:763 [inline]
 grow_dev_folio fs/buffer.c:1047 [inline]
 grow_buffers fs/buffer.c:1113 [inline]
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x1f6/0x6e0 fs/buffer.c:1458
 __getblk include/linux/buffer_head.h:380 [inline]
 sb_getblk include/linux/buffer_head.h:386 [inline]
 ocfs2_read_blocks+0x57e/0x15e0 fs/ocfs2/buffer_head_io.c:236
 ocfs2_read_inode_block_full fs/ocfs2/inode.c:1735 [inline]
 ocfs2_read_inode_block+0xec/0x1d0 fs/ocfs2/inode.c:1749
 ocfs2_assign_bh fs/ocfs2/dlmglue.c:2415 [inline]
 ocfs2_inode_lock_full_nested+0x2ac/0x1bd0 fs/ocfs2/dlmglue.c:2510
 ocfs2_reflink_inodes_lock+0x477/0xc50 fs/ocfs2/refcounttree.c:4744
 ocfs2_remap_file_range+0x236/0x6f0 fs/ocfs2/file.c:2721
 vfs_copy_file_range+0xd80/0x1370 fs/read_write.c:1600
 __do_sys_copy_file_range fs/read_write.c:1683 [inline]
 __se_sys_copy_file_range+0x2fb/0x480 fs/read_write.c:1650
page last free pid 5322 tgid 5321 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xed5/0x16d0 mm/page_alloc.c:3040
 folios_put_refs+0x789/0x8d0 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 mapping_try_invalidate+0x3c2/0x4c0 mm/truncate.c:579
 loop_set_status+0x29b/0xe40 drivers/block/loop.c:1246
 loop_set_status_old drivers/block/loop.c:1362 [inline]
 lo_ioctl+0xce6/0x1fb0 drivers/block/loop.c:1551
 blkdev_ioctl+0x5e3/0x740 block/ioctl.c:804
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888056cb9f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888056cb9f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888056cba000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888056cba080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888056cba100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (3):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/02 06:50 upstream 9147566d8016 0cb124d5 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: use-after-free Write in ocfs2_write_end_nolock
2026/03/28 15:03 upstream be762d8b6dd7 b5ceaad2 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: use-after-free Write in ocfs2_write_end_nolock
2026/03/27 04:47 upstream 46b513250491 50cdcaa1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: use-after-free Write in ocfs2_write_end_nolock
* Struck through repros no longer work on HEAD.