6.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chao Yu chao@kernel.org
[ Upstream commit 7c30d79930132466f5be7d0b57add14d1a016bda ]
syzbot reported an UAF issue as below: [1] [2]
[1] https://syzkaller.appspot.com/text?tag=CrashReport&x=16594c60580000
================================================================== BUG: KASAN: use-after-free in __list_del_entry_valid+0xa6/0x130 lib/list_debug.c:62 Read of size 8 at addr ffff888100567dc8 by task kworker/u4:0/8
CPU: 1 PID: 8 Comm: kworker/u4:0 Tainted: G W 6.1.129-syzkaller-00017-g642656a36791 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Workqueue: writeback wb_workfn (flush-7:0) Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x151/0x1b7 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:316 [inline] print_report+0x158/0x4e0 mm/kasan/report.c:427 kasan_report+0x13c/0x170 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+0x100/0x2e0 fs/f2fs/super.c:1553 f2fs_update_inode+0x72/0x1c40 fs/f2fs/inode.c:588 f2fs_update_inode_page+0x135/0x170 fs/f2fs/inode.c:706 f2fs_write_inode+0x416/0x790 fs/f2fs/inode.c:734 write_inode fs/fs-writeback.c:1460 [inline] __writeback_single_inode+0x4cf/0xb80 fs/fs-writeback.c:1677 writeback_sb_inodes+0xb32/0x1910 fs/fs-writeback.c:1903 __writeback_inodes_wb+0x118/0x3f0 fs/fs-writeback.c:1974 wb_writeback+0x3da/0xa00 fs/fs-writeback.c:2081 wb_check_background_flush fs/fs-writeback.c:2151 [inline] wb_do_writeback fs/fs-writeback.c:2239 [inline] wb_workfn+0xbba/0x1030 fs/fs-writeback.c:2266 process_one_work+0x73d/0xcb0 kernel/workqueue.c:2299 worker_thread+0xa60/0x1260 kernel/workqueue.c:2446 kthread+0x26d/0x300 kernel/kthread.c:386 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK>
Allocated by task 298: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_alloc_info+0x1f/0x30 mm/kasan/generic.c:505 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:333 kasan_slab_alloc include/linux/kasan.h:202 [inline] slab_post_alloc_hook+0x53/0x2c0 mm/slab.h:768 slab_alloc_node mm/slub.c:3421 [inline] slab_alloc mm/slub.c:3431 [inline] __kmem_cache_alloc_lru mm/slub.c:3438 [inline] kmem_cache_alloc_lru+0x102/0x270 mm/slub.c:3454 alloc_inode_sb include/linux/fs.h:3255 [inline] f2fs_alloc_inode+0x2d/0x350 fs/f2fs/super.c:1437 alloc_inode fs/inode.c:261 [inline] iget_locked+0x18c/0x7e0 fs/inode.c:1373 f2fs_iget+0x55/0x4ca0 fs/f2fs/inode.c:486 f2fs_lookup+0x3c1/0xb50 fs/f2fs/namei.c:484 __lookup_slow+0x2b9/0x3e0 fs/namei.c:1689 lookup_slow+0x5a/0x80 fs/namei.c:1706 walk_component+0x2e7/0x410 fs/namei.c:1997 lookup_last fs/namei.c:2454 [inline] path_lookupat+0x16d/0x450 fs/namei.c:2478 filename_lookup+0x251/0x600 fs/namei.c:2507 vfs_statx+0x107/0x4b0 fs/stat.c:229 vfs_fstatat fs/stat.c:267 [inline] vfs_lstat include/linux/fs.h:3434 [inline] __do_sys_newlstat fs/stat.c:423 [inline] __se_sys_newlstat+0xda/0x7c0 fs/stat.c:417 __x64_sys_newlstat+0x5b/0x70 fs/stat.c:417 x64_sys_call+0x52/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:7 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2
Freed by task 0: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4b/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:516 ____kasan_slab_free+0x131/0x180 mm/kasan/common.c:241 __kasan_slab_free+0x11/0x20 mm/kasan/common.c:249 kasan_slab_free include/linux/kasan.h:178 [inline] slab_free_hook mm/slub.c:1745 [inline] slab_free_freelist_hook mm/slub.c:1771 [inline] slab_free mm/slub.c:3686 [inline] kmem_cache_free+0x291/0x560 mm/slub.c:3711 f2fs_free_inode+0x24/0x30 fs/f2fs/super.c:1584 i_callback+0x4b/0x70 fs/inode.c:250 rcu_do_batch+0x552/0xbe0 kernel/rcu/tree.c:2297 rcu_core+0x502/0xf40 kernel/rcu/tree.c:2557 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2574 handle_softirqs+0x1db/0x650 kernel/softirq.c:624 __do_softirq kernel/softirq.c:662 [inline] invoke_softirq kernel/softirq.c:479 [inline] __irq_exit_rcu+0x52/0xf0 kernel/softirq.c:711 irq_exit_rcu+0x9/0x10 kernel/softirq.c:723 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline] sysvec_apic_timer_interrupt+0xa9/0xc0 arch/x86/kernel/apic/apic.c:1118 asm_sysvec_apic_timer_interrupt+0x1b/0x20 arch/x86/include/asm/idtentry.h:691
Last potentially related work creation: kasan_save_stack+0x3b/0x60 mm/kasan/common.c:45 __kasan_record_aux_stack+0xb4/0xc0 mm/kasan/generic.c:486 kasan_record_aux_stack_noalloc+0xb/0x10 mm/kasan/generic.c:496 __call_rcu_common kernel/rcu/tree.c:2807 [inline] call_rcu+0xdc/0x10f0 kernel/rcu/tree.c:2926 destroy_inode fs/inode.c:316 [inline] evict+0x87d/0x930 fs/inode.c:720 iput_final fs/inode.c:1834 [inline] iput+0x616/0x690 fs/inode.c:1860 do_unlinkat+0x4e1/0x920 fs/namei.c:4396 __do_sys_unlink fs/namei.c:4437 [inline] __se_sys_unlink fs/namei.c:4435 [inline] __x64_sys_unlink+0x49/0x50 fs/namei.c:4435 x64_sys_call+0x289/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:88 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:81 entry_SYSCALL_64_after_hwframe+0x68/0xd2
The buggy address belongs to the object at ffff888100567a10 which belongs to the cache f2fs_inode_cache of size 1360 The buggy address is located 952 bytes inside of 1360-byte region [ffff888100567a10, ffff888100567f60)
The buggy address belongs to the physical page: page:ffffea0004015800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x100560 head:ffffea0004015800 order:3 compound_mapcount:0 compound_pincount:0 flags: 0x4000000000010200(slab|head|zone=1) raw: 4000000000010200 0000000000000000 dead000000000122 ffff8881002c4d80 raw: 0000000000000000 0000000080160016 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 3, migratetype Reclaimable, gfp_mask 0xd2050(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_RECLAIMABLE), pid 298, tgid 298 (syz-executor330), ts 26489303743, free_ts 0 set_page_owner include/linux/page_owner.h:33 [inline] post_alloc_hook+0x213/0x220 mm/page_alloc.c:2637 prep_new_page+0x1b/0x110 mm/page_alloc.c:2644 get_page_from_freelist+0x3a98/0x3b10 mm/page_alloc.c:4539 __alloc_pages+0x234/0x610 mm/page_alloc.c:5837 alloc_slab_page+0x6c/0xf0 include/linux/gfp.h:-1 allocate_slab mm/slub.c:1962 [inline] new_slab+0x90/0x3e0 mm/slub.c:2015 ___slab_alloc+0x6f9/0xb80 mm/slub.c:3203 __slab_alloc+0x5d/0xa0 mm/slub.c:3302 slab_alloc_node mm/slub.c:3387 [inline] slab_alloc mm/slub.c:3431 [inline] __kmem_cache_alloc_lru mm/slub.c:3438 [inline] kmem_cache_alloc_lru+0x149/0x270 mm/slub.c:3454 alloc_inode_sb include/linux/fs.h:3255 [inline] f2fs_alloc_inode+0x2d/0x350 fs/f2fs/super.c:1437 alloc_inode fs/inode.c:261 [inline] iget_locked+0x18c/0x7e0 fs/inode.c:1373 f2fs_iget+0x55/0x4ca0 fs/f2fs/inode.c:486 f2fs_fill_super+0x5360/0x6dc0 fs/f2fs/super.c:4488 mount_bdev+0x282/0x3b0 fs/super.c:1445 f2fs_mount+0x34/0x40 fs/f2fs/super.c:4743 legacy_get_tree+0xf1/0x190 fs/fs_context.c:632 page_owner free stack trace missing
Memory state around the buggy address: ffff888100567c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888100567d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888100567d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^ ffff888100567e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888100567e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================
[2] https://syzkaller.appspot.com/text?tag=CrashLog&x=13654c60580000
[ 24.675720][ T28] audit: type=1400 audit(1745327318.732:72): avc: denied { write } for pid=298 comm="syz-executor399" name="/" dev="loop0" ino=3 scontext=root:sysadm_r:sysadm_t tcontext=system_u:object_r:unlabeled_t tclass=dir permissive=1 [ 24.705426][ T296] ------------[ cut here ]------------ [ 24.706608][ T28] audit: type=1400 audit(1745327318.732:73): avc: denied { remove_name } for pid=298 comm="syz-executor399" name="file0" dev="loop0" ino=4 scontext=root:sysadm_r:sysadm_t tcontext=system_u:object_r:unlabeled_t tclass=dir permissive=1 [ 24.711550][ T296] WARNING: CPU: 0 PID: 296 at fs/f2fs/inode.c:847 f2fs_evict_inode+0x1262/0x1540 [ 24.734141][ T28] audit: type=1400 audit(1745327318.732:74): avc: denied { rename } for pid=298 comm="syz-executor399" name="file0" dev="loop0" ino=4 scontext=root:sysadm_r:sysadm_t tcontext=system_u:object_r:unlabeled_t tclass=dir permissive=1 [ 24.742969][ T296] Modules linked in: [ 24.765201][ T28] audit: type=1400 audit(1745327318.732:75): avc: denied { add_name } for pid=298 comm="syz-executor399" name="bus" scontext=root:sysadm_r:sysadm_t tcontext=system_u:object_r:unlabeled_t tclass=dir permissive=1 [ 24.768847][ T296] CPU: 0 PID: 296 Comm: syz-executor399 Not tainted 6.1.129-syzkaller-00017-g642656a36791 #0 [ 24.799506][ T296] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 [ 24.809401][ T296] RIP: 0010:f2fs_evict_inode+0x1262/0x1540 [ 24.815018][ T296] Code: 34 70 4a ff eb 0d e8 2d 70 4a ff 4d 89 e5 4c 8b 64 24 18 48 8b 5c 24 28 4c 89 e7 e8 78 38 03 00 e9 84 fc ff ff e8 0e 70 4a ff <0f> 0b 4c 89 f7 be 08 00 00 00 e8 7f 21 92 ff f0 41 80 0e 04 e9 61 [ 24.834584][ T296] RSP: 0018:ffffc90000db7a40 EFLAGS: 00010293 [ 24.840465][ T296] RAX: ffffffff822aca42 RBX: 0000000000000002 RCX: ffff888110948000 [ 24.848291][ T296] RDX: 0000000000000000 RSI: 0000000000000002 RDI: 0000000000000000 [ 24.856064][ T296] RBP: ffffc90000db7bb0 R08: ffffffff822ac6a8 R09: ffffed10200b005d [ 24.864073][ T296] R10: 0000000000000000 R11: dffffc0000000001 R12: ffff888100580000 [ 24.871812][ T296] R13: dffffc0000000000 R14: ffff88810fef4078 R15: 1ffff920001b6f5c
The root cause is w/ a fuzzed image, f2fs may missed to clear FI_DIRTY_INODE flag for target inode, after f2fs_evict_inode(), the inode is still linked in sbi->inode_list[DIRTY_META] global list, once it triggers checkpoint, f2fs_sync_inode_meta() may access the released inode.
In f2fs_evict_inode(), let's always call f2fs_inode_synced() to clear FI_DIRTY_INODE flag and drop inode from global dirty list to avoid this UAF issue.
Fixes: 0f18b462b2e5 ("f2fs: flush inode metadata when checkpoint is doing") Closes: https://syzkaller.appspot.com/bug?extid=849174b2efaf0d8be6ba 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 | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/f2fs/inode.c b/fs/f2fs/inode.c index f5991e8751b9..b9a1e428b23f 100644 --- a/fs/f2fs/inode.c +++ b/fs/f2fs/inode.c @@ -950,8 +950,12 @@ void f2fs_evict_inode(struct inode *inode) if (likely(!f2fs_cp_error(sbi) && !is_sbi_flag_set(sbi, SBI_CP_DISABLED))) f2fs_bug_on(sbi, is_inode_flag_set(inode, FI_DIRTY_INODE)); - else - f2fs_inode_synced(inode); + + /* + * anyway, it needs to remove the inode from sbi->inode_list[DIRTY_META] + * list to avoid UAF in f2fs_sync_inode_meta() during checkpoint. + */ + f2fs_inode_synced(inode);
/* for the case f2fs_new_inode() was failed, .i_ino is zero, skip it */ if (inode->i_ino)