syzbot

 sign-in | mailing list | source | docs
🐞 Open [1596]
≡ Subsystems
🐞 Fixed [6224]
🐞 Invalid [15742]
⬇ Missing Backports [183]
≡ Crashes
Kernel Health Bugs/Month Bug Lifetimes Fuzzing
Total Repo Heatmap Subsystems Heatmap
💬 Send us feedback

KASAN: use-after-free Read in bch2_checksum

Status: upstream: reported C repro on 2025/05/11 12:57
Subsystems: bcachefs
[Documentation on labels]
Reported-by: syzbot+7d5c34b9ec9fe139fc0c@syzkaller.appspotmail.com
First crash: 4d21h, last: 3d16h
Cause bisection: failed (error log, bisect log)
  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bcachefs?] KASAN: use-after-free Read in bch2_checksum 0 (1) 2025/05/11 12:57
▶ ▼ Similar bugs (1)
Kernel Title Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in bch2_checksum bcachefs C done 34 7d07h 298d 28/28 fixed on 2025/05/06 15:33

Sample crash report:
  node offset 8/40 bset u64s 375: checksum error, type chacha20_poly1305_128: got eb21ae8bf0ac3fa53472f8290f6e6780 should be 61ec379a8789477e76ff1a5280fd6dbd, fixing
==================================================================
BUG: KASAN: use-after-free in poly1305_update include/crypto/poly1305.h:83 [inline]
BUG: KASAN: use-after-free in bch2_checksum+0x209/0x490 fs/bcachefs/checksum.c:157
Read of size 8 at addr ffff888070915af0 by task syz-executor367/5826

CPU: 1 UID: 0 PID: 5826 Comm: syz-executor367 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/29/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xb4/0x290 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x29a/0x2b0 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 poly1305_update include/crypto/poly1305.h:83 [inline]
 bch2_checksum+0x209/0x490 fs/bcachefs/checksum.c:157
 bch2_btree_node_read_done+0x1003/0x5470 fs/bcachefs/btree_io.c:1132
 btree_node_read_work+0x565/0xef0 fs/bcachefs/btree_io.c:1366
 bch2_btree_node_read+0x2151/0x27a0 fs/bcachefs/btree_io.c:-1
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1797 [inline]
 bch2_btree_root_read+0x5e7/0x750 fs/bcachefs/btree_io.c:1819
 read_btree_roots+0x2cb/0x800 fs/bcachefs/recovery.c:582
 bch2_fs_recovery+0x2356/0x37b0 fs/bcachefs/recovery.c:929
 bch2_fs_start+0x70b/0xae0 fs/bcachefs/super.c:1091
 bch2_fs_get_tree+0xd99/0x13a0 fs/bcachefs/fs.c:2570
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1759
 do_new_mount+0x24a/0xa40 fs/namespace.c:3884
 do_mount fs/namespace.c:4224 [inline]
 __do_sys_mount fs/namespace.c:4435 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff05760c2fa
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ff0575c1088 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ff0575c10a0 RCX: 00007ff05760c2fa
RDX: 000020000000f640 RSI: 0000200000000080 RDI: 00007ff0575c10a0
RBP: 0000200000000080 R08: 00007ff0575c10e0 R09: 000000000000f5fe
R10: 0000000000010000 R11: 0000000000000282 R12: 000020000000f640
R13: 00007ff0575c10e0 R14: 0000000000000003 R15: 0000000000010000
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x70915
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 5, migratetype Reclaimable, gfp_mask 0x452cd0(GFP_KERNEL_ACCOUNT|__GFP_RECLAIMABLE|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5826, tgid 5825 (syz-executor367), ts 88234860937, free_ts 88442709891
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1d8/0x230 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x21c7/0x22a0 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4970
 __alloc_pages_noprof+0xa/0x30 mm/page_alloc.c:5004
 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
 ___kmalloc_large_node+0x85/0x200 mm/slub.c:4271
 __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:4299
 __do_kmalloc_node mm/slub.c:4315 [inline]
 __kvmalloc_node_noprof+0x74/0x5e0 mm/slub.c:5012
 btree_node_data_alloc+0xd5/0x260 fs/bcachefs/btree_cache.c:156
 __bch2_btree_node_mem_alloc+0x1ed/0x410 fs/bcachefs/btree_cache.c:201
 bch2_fs_btree_cache_init+0x2c9/0x680 fs/bcachefs/btree_cache.c:656
 bch2_fs_alloc fs/bcachefs/super.c:909 [inline]
 bch2_fs_open+0x235e/0x2820 fs/bcachefs/super.c:2205
 bch2_fs_get_tree+0x45d/0x13a0 fs/bcachefs/fs.c:2489
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1759
 do_new_mount+0x24a/0xa40 fs/namespace.c:3884
 do_mount fs/namespace.c:4224 [inline]
 __do_sys_mount fs/namespace.c:4435 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
page last free pid 5826 tgid 5825 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 __free_pages_ok+0x910/0xac0 mm/page_alloc.c:1438
 __folio_put+0x21b/0x2c0 mm/swap.c:112
 folio_put include/linux/mm.h:1580 [inline]
 free_large_kmalloc+0x145/0x200 mm/slub.c:4767
 btree_bounce_free fs/bcachefs/btree_io.c:112 [inline]
 bch2_btree_node_read_done+0x3450/0x5470 fs/bcachefs/btree_io.c:1245
 btree_node_read_work+0x565/0xef0 fs/bcachefs/btree_io.c:1366
 bch2_btree_node_read+0x2151/0x27a0 fs/bcachefs/btree_io.c:-1
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1797 [inline]
 bch2_btree_root_read+0x5e7/0x750 fs/bcachefs/btree_io.c:1819
 read_btree_roots+0x2cb/0x800 fs/bcachefs/recovery.c:582
 bch2_fs_recovery+0x2356/0x37b0 fs/bcachefs/recovery.c:929
 bch2_fs_start+0x70b/0xae0 fs/bcachefs/super.c:1091
 bch2_fs_get_tree+0xd99/0x13a0 fs/bcachefs/fs.c:2570
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1759
 do_new_mount+0x24a/0xa40 fs/namespace.c:3884
 do_mount fs/namespace.c:4224 [inline]
 __do_sys_mount fs/namespace.c:4435 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888070915980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888070915a00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888070915a80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff888070915b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888070915b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/05/08 09:51 upstream d76bb1ebb558 dbf35fa1 .config strace log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-upstream-fs KASAN: use-after-free Read in bch2_checksum
2025/05/08 07:23 upstream d76bb1ebb558 dbf35fa1 .config console log report syz / log C [disk image (non-bootable)] [vmlinux] [kernel image] [mounted in repro] ci-snapshot-upstream-root KASAN: slab-out-of-bounds Read in bch2_checksum
2025/05/08 17:03 upstream d76bb1ebb558 dbf35fa1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: use-after-free Read in bch2_checksum
2025/05/08 07:06 upstream d76bb1ebb558 dbf35fa1 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: use-after-free Read in bch2_checksum
2025/05/07 12:53 upstream 0d8d44db295c 350f4ffc .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root KASAN: use-after-free Read in bch2_checksum
* Struck through repros no longer work on HEAD.