6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chao Yu chao@kernel.org
[ Upstream commit a509a55f8eecc8970b3980c6f06886bbff0e2f68 ]
As syzbot [1] reported as below:
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffe17473450 R13: 00007f28b1c10854 R14: 000000000000dae5 R15: 00007ffe17474520 </TASK> ---[ end trace 0000000000000000 ]--- ================================================================== BUG: KASAN: use-after-free in __list_del_entry_valid+0xa6/0x130 lib/list_debug.c:62 Read of size 8 at addr ffff88812d962278 by task syz-executor/564
CPU: 1 PID: 564 Comm: syz-executor Tainted: G W 6.1.129-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call Trace: <TASK> __dump_stack+0x21/0x24 lib/dump_stack.c:88 dump_stack_lvl+0xee/0x158 lib/dump_stack.c:106 print_address_description+0x71/0x210 mm/kasan/report.c:316 print_report+0x4a/0x60 mm/kasan/report.c:427 kasan_report+0x122/0x150 mm/kasan/report.c:531 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report_generic.c:351 __list_del_entry_valid+0xa6/0x130 lib/list_debug.c:62 __list_del_entry include/linux/list.h:134 [inline] list_del_init include/linux/list.h:206 [inline] f2fs_inode_synced+0xf7/0x2e0 fs/f2fs/super.c:1531 f2fs_update_inode+0x74/0x1c40 fs/f2fs/inode.c:585 f2fs_update_inode_page+0x137/0x170 fs/f2fs/inode.c:703 f2fs_write_inode+0x4ec/0x770 fs/f2fs/inode.c:731 write_inode fs/fs-writeback.c:1460 [inline] __writeback_single_inode+0x4a0/0xab0 fs/fs-writeback.c:1677 writeback_single_inode+0x221/0x8b0 fs/fs-writeback.c:1733 sync_inode_metadata+0xb6/0x110 fs/fs-writeback.c:2789 f2fs_sync_inode_meta+0x16d/0x2a0 fs/f2fs/checkpoint.c:1159 block_operations fs/f2fs/checkpoint.c:1269 [inline] f2fs_write_checkpoint+0xca3/0x2100 fs/f2fs/checkpoint.c:1658 kill_f2fs_super+0x231/0x390 fs/f2fs/super.c:4668 deactivate_locked_super+0x98/0x100 fs/super.c:332 deactivate_super+0xaf/0xe0 fs/super.c:363 cleanup_mnt+0x45f/0x4e0 fs/namespace.c:1186 __cleanup_mnt+0x19/0x20 fs/namespace.c:1193 task_work_run+0x1c6/0x230 kernel/task_work.c:203 exit_task_work include/linux/task_work.h:39 [inline] do_exit+0x9fb/0x2410 kernel/exit.c:871 do_group_exit+0x210/0x2d0 kernel/exit.c:1021 __do_sys_exit_group kernel/exit.c:1032 [inline] __se_sys_exit_group kernel/exit.c:1030 [inline] __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1030 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2 RIP: 0033:0x7f28b1b8e169 Code: Unable to access opcode bytes at 0x7f28b1b8e13f. RSP: 002b:00007ffe174710a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 RAX: ffffffffffffffda RBX: 00007f28b1c10879 RCX: 00007f28b1b8e169 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000001 RBP: 0000000000000002 R08: 00007ffe1746ee47 R09: 00007ffe17472360 R10: 0000000000000009 R11: 0000000000000246 R12: 00007ffe17472360 R13: 00007f28b1c10854 R14: 000000000000dae5 R15: 00007ffe17474520 </TASK>
Allocated by task 569: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_alloc_info+0x25/0x30 mm/kasan/generic.c:505 __kasan_slab_alloc+0x72/0x80 mm/kasan/common.c:328 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook+0x4f/0x2c0 mm/slab.h:737 slab_alloc_node mm/slub.c:3398 [inline] slab_alloc mm/slub.c:3406 [inline] __kmem_cache_alloc_lru mm/slub.c:3413 [inline] kmem_cache_alloc_lru+0x104/0x220 mm/slub.c:3429 alloc_inode_sb include/linux/fs.h:3245 [inline] f2fs_alloc_inode+0x2d/0x340 fs/f2fs/super.c:1419 alloc_inode fs/inode.c:261 [inline] iget_locked+0x186/0x880 fs/inode.c:1373 f2fs_iget+0x55/0x4c60 fs/f2fs/inode.c:483 f2fs_lookup+0x366/0xab0 fs/f2fs/namei.c:487 __lookup_slow+0x2a3/0x3d0 fs/namei.c:1690 lookup_slow+0x57/0x70 fs/namei.c:1707 walk_component+0x2e6/0x410 fs/namei.c:1998 lookup_last fs/namei.c:2455 [inline] path_lookupat+0x180/0x490 fs/namei.c:2479 filename_lookup+0x1f0/0x500 fs/namei.c:2508 vfs_statx+0x10b/0x660 fs/stat.c:229 vfs_fstatat fs/stat.c:267 [inline] vfs_lstat include/linux/fs.h:3424 [inline] __do_sys_newlstat fs/stat.c:423 [inline] __se_sys_newlstat+0xd5/0x350 fs/stat.c:417 __x64_sys_newlstat+0x5b/0x70 fs/stat.c:417 x64_sys_call+0x393/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:7 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 13: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x31/0x50 mm/kasan/generic.c:516 ____kasan_slab_free+0x132/0x180 mm/kasan/common.c:236 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:244 kasan_slab_free include/linux/kasan.h:177 [inline] slab_free_hook mm/slub.c:1724 [inline] slab_free_freelist_hook+0xc2/0x190 mm/slub.c:1750 slab_free mm/slub.c:3661 [inline] kmem_cache_free+0x12d/0x2a0 mm/slub.c:3683 f2fs_free_inode+0x24/0x30 fs/f2fs/super.c:1562 i_callback+0x4c/0x70 fs/inode.c:250 rcu_do_batch+0x503/0xb80 kernel/rcu/tree.c:2297 rcu_core+0x5a2/0xe70 kernel/rcu/tree.c:2557 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574 handle_softirqs+0x178/0x500 kernel/softirq.c:578 run_ksoftirqd+0x28/0x30 kernel/softirq.c:945 smpboot_thread_fn+0x45a/0x8c0 kernel/smpboot.c:164 kthread+0x270/0x310 kernel/kthread.c:376 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
Last potentially related work creation: kasan_save_stack+0x3a/0x60 mm/kasan/common.c:45 __kasan_record_aux_stack+0xb6/0xc0 mm/kasan/generic.c:486 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496 call_rcu+0xd4/0xf70 kernel/rcu/tree.c:2845 destroy_inode fs/inode.c:316 [inline] evict+0x7da/0x870 fs/inode.c:720 iput_final fs/inode.c:1834 [inline] iput+0x62b/0x830 fs/inode.c:1860 do_unlinkat+0x356/0x540 fs/namei.c:4397 __do_sys_unlink fs/namei.c:4438 [inline] __se_sys_unlink fs/namei.c:4436 [inline] __x64_sys_unlink+0x49/0x50 fs/namei.c:4436 x64_sys_call+0x958/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:88 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff88812d961f20 which belongs to the cache f2fs_inode_cache of size 1200 The buggy address is located 856 bytes inside of 1200-byte region [ffff88812d961f20, ffff88812d9623d0)
The buggy address belongs to the physical page: page:ffffea0004b65800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x12d960 head:ffffea0004b65800 order:2 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 dead000000000122 ffff88810a94c500 raw: 0000000000000000 00000000800c000c 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Reclaimable, gfp_mask 0x1d2050(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL|__GFP_RECLAIMABLE), pid 569, tgid 568 (syz.2.16), ts 55943246141, free_ts 0 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1d0/0x1f0 mm/page_alloc.c:2532 prep_new_page mm/page_alloc.c:2539 [inline] get_page_from_freelist+0x2e63/0x2ef0 mm/page_alloc.c:4328 __alloc_pages+0x235/0x4b0 mm/page_alloc.c:5605 alloc_slab_page include/linux/gfp.h:-1 [inline] allocate_slab mm/slub.c:1939 [inline] new_slab+0xec/0x4b0 mm/slub.c:1992 ___slab_alloc+0x6f6/0xb50 mm/slub.c:3180 __slab_alloc+0x5e/0xa0 mm/slub.c:3279 slab_alloc_node mm/slub.c:3364 [inline] slab_alloc mm/slub.c:3406 [inline] __kmem_cache_alloc_lru mm/slub.c:3413 [inline] kmem_cache_alloc_lru+0x13f/0x220 mm/slub.c:3429 alloc_inode_sb include/linux/fs.h:3245 [inline] f2fs_alloc_inode+0x2d/0x340 fs/f2fs/super.c:1419 alloc_inode fs/inode.c:261 [inline] iget_locked+0x186/0x880 fs/inode.c:1373 f2fs_iget+0x55/0x4c60 fs/f2fs/inode.c:483 f2fs_fill_super+0x3ad7/0x6bb0 fs/f2fs/super.c:4293 mount_bdev+0x2ae/0x3e0 fs/super.c:1443 f2fs_mount+0x34/0x40 fs/f2fs/super.c:4642 legacy_get_tree+0xea/0x190 fs/fs_context.c:632 vfs_get_tree+0x89/0x260 fs/super.c:1573 do_new_mount+0x25a/0xa20 fs/namespace.c:3056 page_owner free stack trace missing
Memory state around the buggy address: ffff88812d962100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88812d962180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff88812d962200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff88812d962280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88812d962300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
[1] https://syzkaller.appspot.com/x/report.txt?x=13448368580000
This bug can be reproduced w/ the reproducer [2], once we enable CONFIG_F2FS_CHECK_FS config, the reproducer will trigger panic as below, so the direct reason of this bug is the same as the one below patch [3] fixed.
kernel BUG at fs/f2fs/inode.c:857! RIP: 0010:f2fs_evict_inode+0x1204/0x1a20 Call Trace: <TASK> evict+0x32a/0x7a0 do_unlinkat+0x37b/0x5b0 __x64_sys_unlink+0xad/0x100 do_syscall_64+0x5a/0xb0 entry_SYSCALL_64_after_hwframe+0x6e/0xd8 RIP: 0010:f2fs_evict_inode+0x1204/0x1a20
[2] https://syzkaller.appspot.com/x/repro.c?x=17495ccc580000 [3] https://lore.kernel.org/linux-f2fs-devel/20250702120321.1080759-1-chao@kerne...
Tracepoints before panic:
f2fs_unlink_enter: dev = (7,0), dir ino = 3, i_size = 4096, i_blocks = 8, name = file1 f2fs_unlink_exit: dev = (7,0), ino = 7, ret = 0 f2fs_evict_inode: dev = (7,0), ino = 7, pino = 3, i_mode = 0x81ed, i_size = 10, i_nlink = 0, i_blocks = 0, i_advise = 0x0 f2fs_truncate_node: dev = (7,0), ino = 7, nid = 8, block_address = 0x3c05
f2fs_unlink_enter: dev = (7,0), dir ino = 3, i_size = 4096, i_blocks = 8, name = file3 f2fs_unlink_exit: dev = (7,0), ino = 8, ret = 0 f2fs_evict_inode: dev = (7,0), ino = 8, pino = 3, i_mode = 0x81ed, i_size = 9000, i_nlink = 0, i_blocks = 24, i_advise = 0x4 f2fs_truncate: dev = (7,0), ino = 8, pino = 3, i_mode = 0x81ed, i_size = 0, i_nlink = 0, i_blocks = 24, i_advise = 0x4 f2fs_truncate_blocks_enter: dev = (7,0), ino = 8, i_size = 0, i_blocks = 24, start file offset = 0 f2fs_truncate_blocks_exit: dev = (7,0), ino = 8, ret = -2
The root cause is: in the fuzzed image, dnode #8 belongs to inode #7, after inode #7 eviction, dnode #8 was dropped.
However there is dirent that has ino #8, so, once we unlink file3, in f2fs_evict_inode(), both f2fs_truncate() and f2fs_update_inode_page() will fail due to we can not load node #8, result in we missed to call f2fs_inode_synced() to clear inode dirty status.
Let's fix this by calling f2fs_inode_synced() in error path of f2fs_evict_inode().
PS: As I verified, the reproducer [2] can trigger this bug in v6.1.129, but it failed in v6.16-rc4, this is because the testcase will stop due to other corruption has been detected by f2fs:
F2FS-fs (loop0): inconsistent node block, node_type:2, nid:8, node_footer[nid:8,ino:8,ofs:0,cpver:5013063228981249506,blkaddr:15366] F2FS-fs (loop0): f2fs_lookup: inode (ino=9) has zero i_nlink
Fixes: 0f18b462b2e5 ("f2fs: flush inode metadata when checkpoint is doing") Closes: https://syzkaller.appspot.com/x/report.txt?x=13448368580000 Signed-off-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/inode.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index 94ed056656d8..76ec2899cbe8 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -905,6 +905,19 @@ void f2fs_evict_inode(struct inode *inode) f2fs_update_inode_page(inode); if (dquot_initialize_needed(inode)) set_sbi_flag(sbi, SBI_QUOTA_NEED_REPAIR); + + /* + * If both f2fs_truncate() and f2fs_update_inode_page() failed + * due to fuzzed corrupted inode, call f2fs_inode_synced() to + * avoid triggering later f2fs_bug_on(). + */ + if (is_inode_flag_set(inode, FI_DIRTY_INODE)) { + f2fs_warn(sbi, + "f2fs_evict_inode: inode is dirty, ino:%lu", + inode->i_ino); + f2fs_inode_synced(inode); + set_sbi_flag(sbi, SBI_NEED_FSCK); + } } if (!is_sbi_flag_set(sbi, SBI_IS_FREEZING)) sb_end_intwrite(inode->i_sb);