Hello. We are Ubisectech Sirius Team, the vulnerability lab of China ValiantSec. Recently, our team has discovered a issue in Linux kernel 6.8. Attached to the email were a PoC file of the issue. Stack dump: R13: 000000000000006e R14: 00007f03a5b34078 R15: 00007f03a6781000 F2FS-fs (loop3): sanity_check_extent_cache: inode (ino=8) extent info [5634, 0, 3] is incorrect, run fsck to fix ================================================================== BUG: KASAN: slab-use-after-free in instrument_atomic_read include/linux/instrumented.h:68 [inline] BUG: KASAN: slab-use-after-free in atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] BUG: KASAN: slab-use-after-free in __destroy_extent_node+0xb8/0x260 fs/f2fs/extent_cache.c:1061 Read of size 4 at addr ffff8880516c3070 by task syz.3.23/9717 CPU: 1 PID: 9717 Comm: syz.3.23 Not tainted 6.10.0-rc6-g1dfe225e9af5 #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x116/0x1b0 lib/dump_stack.c:114 print_address_description mm/kasan/report.c:377 [inline] print_report+0xc0/0x5e0 mm/kasan/report.c:488 kasan_report+0xbd/0xf0 mm/kasan/report.c:601 check_region_inline mm/kasan/generic.c:183 [inline] kasan_check_range+0xf4/0x1a0 mm/kasan/generic.c:189 instrument_atomic_read include/linux/instrumented.h:68 [inline] atomic_read include/linux/atomic/atomic-instrumented.h:32 [inline] __destroy_extent_node+0xb8/0x260 fs/f2fs/extent_cache.c:1061 __destroy_extent_tree+0x14a/0x6f0 fs/f2fs/extent_cache.c:1126 f2fs_destroy_extent_tree+0x17/0x30 fs/f2fs/extent_cache.c:1143 f2fs_evict_inode+0x3ff/0x1da0 fs/f2fs/inode.c:837 evict+0x2ed/0x6c0 fs/inode.c:667 iput_final fs/inode.c:1741 [inline] iput.part.0+0x559/0x760 fs/inode.c:1767 iput+0x5c/0x80 fs/inode.c:1757 f2fs_iget+0xfe6/0x5a40 fs/f2fs/inode.c:627 f2fs_nfs_get_inode fs/f2fs/super.c:3265 [inline] f2fs_nfs_get_inode+0x86/0x130 fs/f2fs/super.c:3251 generic_fh_to_dentry+0xdf/0x110 fs/libfs.c:1456 exportfs_decode_fh_raw+0x12b/0x7a0 fs/exportfs/expfs.c:444 exportfs_decode_fh+0x3c/0x90 fs/exportfs/expfs.c:584 do_handle_to_path fs/fhandle.c:155 [inline] handle_to_path fs/fhandle.c:210 [inline] do_handle_open+0x2bc/0x590 fs/fhandle.c:226 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f03a59958cd Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f03a67a0fa8 EFLAGS: 00000246 ORIG_RAX: 0000000000000130 RAX: ffffffffffffffda RBX: 00007f03a5b34078 RCX: 00007f03a59958cd RDX: 0000000000000000 RSI: 0000000020000040 RDI: 0000000000000004 RBP: 00007f03a5a2d6e6 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000006e R14: 00007f03a5b34078 R15: 00007f03a6781000 Allocated by task 9642: kasan_save_stack+0x24/0x50 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 unpoison_slab_object mm/kasan/common.c:312 [inline] __kasan_slab_alloc+0x87/0x90 mm/kasan/common.c:338 kasan_slab_alloc include/linux/kasan.h:201 [inline] slab_post_alloc_hook mm/slub.c:3940 [inline] slab_alloc_node mm/slub.c:4002 [inline] kmem_cache_alloc_noprof+0x121/0x2f0 mm/slub.c:4009 f2fs_kmem_cache_alloc_nofail fs/f2fs/f2fs.h:2815 [inline] f2fs_kmem_cache_alloc fs/f2fs/f2fs.h:2825 [inline] __grab_extent_tree+0x27c/0x5b0 fs/f2fs/extent_cache.c:334 f2fs_init_read_extent_tree+0x1e2/0x710 fs/f2fs/extent_cache.c:405 do_read_inode fs/f2fs/inode.c:512 [inline] f2fs_iget+0x1e1e/0x5a40 fs/f2fs/inode.c:566 f2fs_nfs_get_inode fs/f2fs/super.c:3265 [inline] f2fs_nfs_get_inode+0x86/0x130 fs/f2fs/super.c:3251 generic_fh_to_dentry+0xdf/0x110 fs/libfs.c:1456 exportfs_decode_fh_raw+0x12b/0x7a0 fs/exportfs/expfs.c:444 exportfs_decode_fh+0x3c/0x90 fs/exportfs/expfs.c:584 do_handle_to_path fs/fhandle.c:155 [inline] handle_to_path fs/fhandle.c:210 [inline] do_handle_open+0x2bc/0x590 fs/fhandle.c:226 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f Freed by task 9642: kasan_save_stack+0x24/0x50 mm/kasan/common.c:47 kasan_save_track+0x14/0x30 mm/kasan/common.c:68 kasan_save_free_info+0x3b/0x60 mm/kasan/generic.c:579 poison_slab_object mm/kasan/common.c:240 [inline] poison_slab_object+0xf9/0x180 mm/kasan/common.c:211 __kasan_slab_free+0x33/0x50 mm/kasan/common.c:256 kasan_slab_free include/linux/kasan.h:184 [inline] slab_free_hook mm/slub.c:2196 [inline] slab_free mm/slub.c:4438 [inline] kmem_cache_free+0x12a/0x3a0 mm/slub.c:4513 __destroy_extent_tree+0x1f8/0x6f0 fs/f2fs/extent_cache.c:1132 f2fs_destroy_extent_tree+0x17/0x30 fs/f2fs/extent_cache.c:1143 f2fs_evict_inode+0x3ff/0x1da0 fs/f2fs/inode.c:837 evict+0x2ed/0x6c0 fs/inode.c:667 iput_final fs/inode.c:1741 [inline] iput.part.0+0x559/0x760 fs/inode.c:1767 iput+0x5c/0x80 fs/inode.c:1757 f2fs_iget+0xfe6/0x5a40 fs/f2fs/inode.c:627 f2fs_nfs_get_inode fs/f2fs/super.c:3265 [inline] f2fs_nfs_get_inode+0x86/0x130 fs/f2fs/super.c:3251 generic_fh_to_dentry+0xdf/0x110 fs/libfs.c:1456 exportfs_decode_fh_raw+0x12b/0x7a0 fs/exportfs/expfs.c:444 exportfs_decode_fh+0x3c/0x90 fs/exportfs/expfs.c:584 do_handle_to_path fs/fhandle.c:155 [inline] handle_to_path fs/fhandle.c:210 [inline] do_handle_open+0x2bc/0x590 fs/fhandle.c:226 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcb/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The buggy address belongs to the object at ffff8880516c3000 which belongs to the cache f2fs_extent_tree of size 144 The buggy address is located 112 bytes inside of freed 144-byte region [ffff8880516c3000, ffff8880516c3090) The buggy address belongs to the physical page: page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x516c3 flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff) page_type: 0xffffefff(slab) raw: 04fff00000000000 ffff888042d6c640 dead000000000122 0000000000000000 raw: 0000000000000000 0000000080130013 00000001ffffefff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 0, migratetype Reclaimable, gfp_mask 0x152c50(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL|__GFP_RECLAIMABLE), pid 9642, tgid 9641 (syz.3.23), ts 151346879967, free_ts 0 set_page_owner include/linux/page_owner.h:32 [inline] post_alloc_hook+0x2e7/0x350 mm/page_alloc.c:1473 prep_new_page mm/page_alloc.c:1481 [inline] get_page_from_freelist+0xbf4/0x2850 mm/page_alloc.c:3425 __alloc_pages_noprof+0x214/0x21e0 mm/page_alloc.c:4683 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline] alloc_pages_node_noprof include/linux/gfp.h:296 [inline] alloc_slab_page+0x5d/0x120 mm/slub.c:2265 allocate_slab mm/slub.c:2428 [inline] new_slab+0x83/0x260 mm/slub.c:2481 ___slab_alloc+0xbb7/0x1850 mm/slub.c:3667 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3757 __slab_alloc_node mm/slub.c:3810 [inline] slab_alloc_node mm/slub.c:3990 [inline] kmem_cache_alloc_noprof+0x2a8/0x2f0 mm/slub.c:4009 f2fs_kmem_cache_alloc_nofail fs/f2fs/f2fs.h:2815 [inline] f2fs_kmem_cache_alloc fs/f2fs/f2fs.h:2825 [inline] __grab_extent_tree+0x27c/0x5b0 fs/f2fs/extent_cache.c:334 f2fs_init_read_extent_tree+0x1e2/0x710 fs/f2fs/extent_cache.c:405 do_read_inode fs/f2fs/inode.c:512 [inline] f2fs_iget+0x1e1e/0x5a40 fs/f2fs/inode.c:566 f2fs_nfs_get_inode fs/f2fs/super.c:3265 [inline] f2fs_nfs_get_inode+0x86/0x130 fs/f2fs/super.c:3251 generic_fh_to_dentry+0xdf/0x110 fs/libfs.c:1456 exportfs_decode_fh_raw+0x12b/0x7a0 fs/exportfs/expfs.c:444 exportfs_decode_fh+0x3c/0x90 fs/exportfs/expfs.c:584 do_handle_to_path fs/fhandle.c:155 [inline] handle_to_path fs/fhandle.c:210 [inline] do_handle_open+0x2bc/0x590 fs/fhandle.c:226 page_owner free stack trace missing Memory state around the buggy address: ffff8880516c2f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880516c2f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8880516c3000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8880516c3080: fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880516c3100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ================================================================== Thank you for taking the time to read this email and we look forward to working with you further.