==================================================================
BUG: KASAN: slab-use-after-free in snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288
Read of size 8 at addr ffff8881185c1998 by task syz.1.340/1525
CPU: 0 UID: 0 PID: 1525 Comm: syz.1.340 Not tainted syzkaller #0 c6d530d213d6421e3ceaeda0202ca36fa97e3e13
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
Call Trace:
__dump_stack+0x21/0x30 lib/dump_stack.c:94
dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
print_address_description+0x71/0x210 mm/kasan/report.c:377
print_report+0x4a/0x70 mm/kasan/report.c:481
kasan_report+0x162/0x1a0 mm/kasan/report.c:594
__asan_report_load8_noabort+0x18/0x20 mm/kasan/report_generic.c:381
snapshot_ctr+0x586/0x1350 drivers/md/dm-snap.c:1288
dm_table_add_target+0x59c/0xcb0 drivers/md/dm-table.c:760
populate_table drivers/md/dm-ioctl.c:1494 [inline]
table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536
ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline]
dm_ctl_ioctl+0x8f3/0xde0 drivers/md/dm-ioctl.c:2129
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
__x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f43c839fb19
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:00007f43c6df7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f43c8626090 RCX: 00007f43c839fb19
RDX: 0000200000000700 RSI: 00000000c138fd09 RDI: 0000000000000004
RBP: 00007f43c8437af8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f43c8626128 R14: 00007f43c8626090 R15: 00007fff648ff338
Allocated by task 1525:
kasan_save_stack mm/kasan/common.c:49 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
kasan_save_alloc_info+0x3a/0x50 mm/kasan/generic.c:565
poison_kmalloc_redzone mm/kasan/common.c:379 [inline]
__kasan_kmalloc+0x96/0xb0 mm/kasan/common.c:396
kasan_kmalloc include/linux/kasan.h:261 [inline]
__kmalloc_cache_node_noprof+0x225/0x430 mm/slub.c:4440
kmalloc_node_noprof include/linux/slab.h:1004 [inline]
open_table_device drivers/md/dm.c:758 [inline]
dm_get_table_device+0x1e3/0x6c0 drivers/md/dm.c:837
dm_get_device+0x32b/0x7f0 drivers/md/dm-table.c:394
snapshot_ctr+0x292/0x1350 drivers/md/dm-snap.c:1273
dm_table_add_target+0x59c/0xcb0 drivers/md/dm-table.c:760
populate_table drivers/md/dm-ioctl.c:1494 [inline]
table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536
ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline]
dm_ctl_ioctl+0x8f3/0xde0 drivers/md/dm-ioctl.c:2129
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
__x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Freed by task 1525:
kasan_save_stack mm/kasan/common.c:49 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
kasan_save_free_info+0x44/0x50 mm/kasan/generic.c:579
poison_slab_object mm/kasan/common.c:249 [inline]
__kasan_slab_free+0x5f/0x80 mm/kasan/common.c:266
kasan_slab_free include/linux/kasan.h:234 [inline]
slab_free_hook mm/slub.c:2445 [inline]
slab_free mm/slub.c:4716 [inline]
kfree+0x158/0x440 mm/slub.c:4877
close_table_device drivers/md/dm.c:814 [inline]
dm_put_table_device+0x298/0x2e0 drivers/md/dm.c:857
upgrade_mode drivers/md/dm-table.c:328 [inline]
dm_get_device+0x571/0x7f0 drivers/md/dm-table.c:405
snapshot_ctr+0x435/0x1350 drivers/md/dm-snap.c:1283
dm_table_add_target+0x59c/0xcb0 drivers/md/dm-table.c:760
populate_table drivers/md/dm-ioctl.c:1494 [inline]
table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536
ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline]
dm_ctl_ioctl+0x8f3/0xde0 drivers/md/dm-ioctl.c:2129
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
__x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
The buggy address belongs to the object at ffff8881185c1980
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 24 bytes inside of
freed 96-byte region [ffff8881185c1980, ffff8881185c19e0)
The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1185c1
anon flags: 0x4000000000000000(zone=1)
page_type: f5(slab)
raw: 4000000000000000 ffff888100041280 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000200020 00000001f5000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x152cc0(GFP_USER|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 295, tgid 295 (syz-executor), ts 30820771404, free_ts 30820664549
set_page_owner include/linux/page_owner.h:35 [inline]
post_alloc_hook+0x37d/0x3b0 mm/page_alloc.c:1864
prep_new_page+0x2d/0x180 mm/page_alloc.c:1872
get_page_from_freelist+0x4aea/0x4ba0 mm/page_alloc.c:3949
__alloc_pages_noprof+0x35a/0x7e0 mm/page_alloc.c:5316
alloc_slab_page+0x6b/0x1e0 mm/slub.c:-1
allocate_slab+0x69/0x430 mm/slub.c:2687
new_slab mm/slub.c:2741 [inline]
___slab_alloc+0x591/0x8c0 mm/slub.c:3934
__slab_alloc mm/slub.c:4025 [inline]
__slab_alloc_node mm/slub.c:4078 [inline]
slab_alloc_node mm/slub.c:4241 [inline]
__kmalloc_cache_node_noprof+0x2ae/0x430 mm/slub.c:4436
kmalloc_node_noprof include/linux/slab.h:1004 [inline]
__get_vm_area_node+0x150/0x390 mm/vmalloc.c:3148
__vmalloc_node_range_noprof+0x340/0x1300 mm/vmalloc.c:3838
__vmalloc_node_noprof mm/vmalloc.c:3949 [inline]
vzalloc_noprof+0x103/0x1d0 mm/vmalloc.c:4022
alloc_counters+0x75/0x520 net/ipv4/netfilter/ip_tables.c:799
copy_entries_to_user net/ipv4/netfilter/ip_tables.c:821 [inline]
get_entries net/ipv4/netfilter/ip_tables.c:1020 [inline]
do_ipt_get_ctl+0xab5/0x1210 net/ipv4/netfilter/ip_tables.c:1665
nf_getsockopt+0x28b/0x2b0 net/netfilter/nf_sockopt.c:116
ip_getsockopt+0x15b/0x200 net/ipv4/ip_sockglue.c:1777
tcp_getsockopt+0x103/0x130 net/ipv4/tcp.c:4709
page last free pid 295 tgid 295 stack trace:
reset_page_owner include/linux/page_owner.h:28 [inline]
free_pages_prepare mm/page_alloc.c:1391 [inline]
free_unref_page+0xb99/0xf50 mm/page_alloc.c:2877
__free_pages+0x6b/0x3b0 mm/page_alloc.c:5403
vfree+0x3ea/0x5b0 mm/vmalloc.c:3410
copy_entries_to_user net/ipv4/netfilter/arp_tables.c:723 [inline]
get_entries net/ipv4/netfilter/arp_tables.c:877 [inline]
do_arpt_get_ctl+0xdd3/0x10e0 net/ipv4/netfilter/arp_tables.c:1470
nf_getsockopt+0x28b/0x2b0 net/netfilter/nf_sockopt.c:116
ip_getsockopt+0x15b/0x200 net/ipv4/ip_sockglue.c:1777
tcp_getsockopt+0x103/0x130 net/ipv4/tcp.c:4709
sock_common_getsockopt+0xaf/0xd0 net/core/sock.c:3847
do_sock_getsockopt+0x3a4/0x6c0 net/socket.c:2375
__sys_getsockopt net/socket.c:2404 [inline]
__do_sys_getsockopt net/socket.c:2411 [inline]
__se_sys_getsockopt net/socket.c:2408 [inline]
__x64_sys_getsockopt+0x1aa/0x250 net/socket.c:2408
x64_sys_call+0x10db/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:56
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
Memory state around the buggy address:
ffff8881185c1880: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
ffff8881185c1900: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
>ffff8881185c1980: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff8881185c1a00: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
ffff8881185c1a80: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 0 UID: 0 PID: 1525 Comm: syz.1.340 Tainted: G B syzkaller #0 c6d530d213d6421e3ceaeda0202ca36fa97e3e13
Tainted: [B]=BAD_PAGE
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:bdev_get_queue include/linux/blkdev.h:1014 [inline]
RIP: 0010:bdev_logical_block_size include/linux/blkdev.h:1368 [inline]
RIP: 0010:dm_exception_store_set_chunk_size drivers/md/dm-exception-store.c:175 [inline]
RIP: 0010:set_chunk_size drivers/md/dm-exception-store.c:158 [inline]
RIP: 0010:dm_exception_store_create+0x6ea/0xa40 drivers/md/dm-exception-store.c:233
Code: 00 fc ff df 80 3c 08 00 74 08 4c 89 ff e8 7e e9 dd fd 4d 8b 3f 49 83 c7 18 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ff e8 58 e9 dd fd 41 bc b0 00 00 00 4d 03
RSP: 0018:ffffc9000ddd7840 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffff88811481c080 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8881185c1998
RBP: ffffc9000ddd7910 R08: ffff88811f9c93c0 R09: 0000000000000002
R10: 0000000000000010 R11: 0000000000000002 R12: ffff888101ace420
R13: 1ffff92001bbaf10 R14: ffff888119274708 R15: 0000000000000018
FS: 00007f43c6df76c0(0000) GS:ffff8881f6c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcb423f72f8 CR3: 000000011995a000 CR4: 00000000003526b0
DR0: 0000000000000008 DR1: 0000000000000007 DR2: 0000000000000004
DR3: 0000000000000034 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Call Trace:
snapshot_ctr+0x674/0x1350 drivers/md/dm-snap.c:1294
dm_table_add_target+0x59c/0xcb0 drivers/md/dm-table.c:760
populate_table drivers/md/dm-ioctl.c:1494 [inline]
table_load+0x2eb/0x7d0 drivers/md/dm-ioctl.c:1536
ctl_ioctl drivers/md/dm-ioctl.c:2107 [inline]
dm_ctl_ioctl+0x8f3/0xde0 drivers/md/dm-ioctl.c:2129
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0x126/0x1b0 fs/ioctl.c:892
__x64_sys_ioctl+0x7f/0xa0 fs/ioctl.c:892
x64_sys_call+0x1878/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:47 [inline]
do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7f43c839fb19
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:00007f43c6df7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f43c8626090 RCX: 00007f43c839fb19
RDX: 0000200000000700 RSI: 00000000c138fd09 RDI: 0000000000000004
RBP: 00007f43c8437af8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f43c8626128 R14: 00007f43c8626090 R15: 00007fff648ff338
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bdev_get_queue include/linux/blkdev.h:1014 [inline]
RIP: 0010:bdev_logical_block_size include/linux/blkdev.h:1368 [inline]
RIP: 0010:dm_exception_store_set_chunk_size drivers/md/dm-exception-store.c:175 [inline]
RIP: 0010:set_chunk_size drivers/md/dm-exception-store.c:158 [inline]
RIP: 0010:dm_exception_store_create+0x6ea/0xa40 drivers/md/dm-exception-store.c:233
Code: 00 fc ff df 80 3c 08 00 74 08 4c 89 ff e8 7e e9 dd fd 4d 8b 3f 49 83 c7 18 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 ff e8 58 e9 dd fd 41 bc b0 00 00 00 4d 03
RSP: 0018:ffffc9000ddd7840 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffff88811481c080 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8881185c1998
RBP: ffffc9000ddd7910 R08: ffff88811f9c93c0 R09: 0000000000000002
R10: 0000000000000010 R11: 0000000000000002 R12: ffff888101ace420
R13: 1ffff92001bbaf10 R14: ffff888119274708 R15: 0000000000000018
FS: 00007f43c6df76c0(0000) GS:ffff8881f6c00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f43c6dd6d58 CR3: 000000011995a000 CR4: 00000000003526b0
DR0: 0000000000000008 DR1: 0000000000000007 DR2: 0000000000000004
DR3: 0000000000000034 DR6: 00000000ffff0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 00 fc add %bh,%ah
2: ff lcall (bad)
3: df 80 3c 08 00 74 filds 0x7400083c(%rax)
9: 08 4c 89 ff or %cl,-0x1(%rcx,%rcx,4)
d: e8 7e e9 dd fd call 0xfddde990
12: 4d 8b 3f mov (%r15),%r15
15: 49 83 c7 18 add $0x18,%r15
19: 4c 89 f8 mov %r15,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 ff mov %r15,%rdi
33: e8 58 e9 dd fd call 0xfddde990
38: 41 bc b0 00 00 00 mov $0xb0,%r12d
3e: 4d rex.WRB
3f: 03 .byte 0x3