Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in __hci_req_sync

syzbot
2024-04-13T07:58:40Z

syzbot has found a reproducer for the following issue on:

HEAD commit: 8f2c057754b2 Merge tag 'arm64-fixes' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16952da3180000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5a8421528fe0176
dashboard link: https://syzkaller.appspot.com/bug?extid=27209997e4015fb4702e
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14905af5180000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=171da243180000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-8f2c0577.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4ed4e9e9deb1/vmlinux-8f2c0577.xz
kernel image: https://storage.googleapis.com/syzbot-assets/136318846a1c/bzImage-8f2c0577.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+27209997e4015fb4702e@syzkaller.appspotmail.com

==================================================================
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 refcount_read include/linux/refcount.h:136 [inline]
BUG: KASAN: slab-use-after-free in skb_unref include/linux/skbuff.h:1227 [inline]
BUG: KASAN: slab-use-after-free in __kfree_skb_reason net/core/skbuff.c:1224 [inline]
BUG: KASAN: slab-use-after-free in kfree_skb_reason+0x36/0x210 net/core/skbuff.c:1251
Read of size 4 at addr ffff888029a1fee4 by task syz-executor145/5234

CPU: 0 PID: 5234 Comm: syz-executor145 Not tainted 6.9.0-rc3-syzkaller-00344-g8f2c057754b2 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc3/0x620 mm/kasan/report.c:488
kasan_report+0xd9/0x110 mm/kasan/report.c:601
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0xef/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]
refcount_read include/linux/refcount.h:136 [inline]
skb_unref include/linux/skbuff.h:1227 [inline]
__kfree_skb_reason net/core/skbuff.c:1224 [inline]
kfree_skb_reason+0x36/0x210 net/core/skbuff.c:1251
kfree_skb include/linux/skbuff.h:1262 [inline]
__hci_req_sync+0x61d/0x980 net/bluetooth/hci_request.c:184
hci_req_sync+0x97/0xd0 net/bluetooth/hci_request.c:206
hci_dev_cmd+0x653/0x9c0 net/bluetooth/hci_core.c:790
hci_sock_ioctl+0x4f3/0x8e0 net/bluetooth/hci_sock.c:1153
hci_sock_compat_ioctl net/bluetooth/hci_sock.c:1180 [inline]
hci_sock_compat_ioctl+0x68/0x80 net/bluetooth/hci_sock.c:1169
compat_sock_ioctl+0x181/0x7f0 net/socket.c:3521
__do_compat_sys_ioctl+0x2c3/0x330 fs/ioctl.c:1004
do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
__do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:321
do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:346
entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf7e3c579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000ffa29e34 EFLAGS: 00000292 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000400448dd
RDX: 00000000ffa29f04 RSI: 00000000f7f0bff4 RDI: 00000000577e83d8
RBP: 00000000ffa2a118 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
</TASK>

Allocated by task 5243:
kasan_save_stack+0x33/0x60 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+0x89/0x90 mm/kasan/common.c:338
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3798 [inline]
slab_alloc_node mm/slub.c:3845 [inline]
kmem_cache_alloc+0x136/0x320 mm/slub.c:3852
skb_clone+0x190/0x3f0 net/core/skbuff.c:2063
hci_send_cmd_sync net/bluetooth/hci_core.c:4220 [inline]
hci_cmd_work+0x66a/0x710 net/bluetooth/hci_core.c:4240
process_one_work+0x902/0x1a30 kernel/workqueue.c:3254
process_scheduled_works kernel/workqueue.c:3335 [inline]
worker_thread+0x6c8/0xf70 kernel/workqueue.c:3416
kthread+0x2c1/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Freed by task 5243:
kasan_save_stack+0x33/0x60 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]
__kasan_slab_free+0x11d/0x1a0 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2106 [inline]
slab_free mm/slub.c:4280 [inline]
kmem_cache_free+0x12e/0x380 mm/slub.c:4344
kfree_skbmem+0x10e/0x200 net/core/skbuff.c:1159
__kfree_skb net/core/skbuff.c:1217 [inline]
kfree_skb_reason+0x13a/0x210 net/core/skbuff.c:1252
kfree_skb include/linux/skbuff.h:1262 [inline]
hci_req_sync_complete+0x16c/0x270 net/bluetooth/hci_request.c:109
hci_event_packet+0x963/0x1190 net/bluetooth/hci_event.c:7604
hci_rx_work+0x2c4/0x1610 net/bluetooth/hci_core.c:4171
process_one_work+0x902/0x1a30 kernel/workqueue.c:3254
process_scheduled_works kernel/workqueue.c:3335 [inline]
worker_thread+0x6c8/0xf70 kernel/workqueue.c:3416
kthread+0x2c1/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

The buggy address belongs to the object at ffff888029a1fe00
which belongs to the cache skbuff_head_cache of size 240
The buggy address is located 228 bytes inside of
freed 240-byte region [ffff888029a1fe00, ffff888029a1fef0)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x29a1e
head: order:1 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff80000000840(slab|head|node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000840 ffff888015fa8780 ffffea00009fee80 0000000000000004
raw: 0000000000000000 0000000000190019 00000001ffffffff 0000000000000000
head: 00fff80000000840 ffff888015fa8780 ffffea00009fee80 0000000000000004
head: 0000000000000000 0000000000190019 00000001ffffffff 0000000000000000
head: 00fff80000000001 ffffea0000a68781 dead000000000122 00000000ffffffff
head: 0000000200000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Unmovable, gfp_mask 0x52820(GFP_ATOMIC|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 5111, tgid 5111 (sshd), ts 41611078310, free_ts 41590764657
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x2d4/0x350 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0xa28/0x3780 mm/page_alloc.c:3317
__alloc_pages+0x22b/0x2460 mm/page_alloc.c:4575
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
alloc_slab_page mm/slub.c:2175 [inline]
allocate_slab mm/slub.c:2338 [inline]
new_slab+0xcc/0x3a0 mm/slub.c:2391
___slab_alloc+0x670/0x16d0 mm/slub.c:3525
__slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3610
__slab_alloc_node mm/slub.c:3663 [inline]
slab_alloc_node mm/slub.c:3835 [inline]
kmem_cache_alloc_node+0x10a/0x340 mm/slub.c:3888
__alloc_skb+0x2b3/0x380 net/core/skbuff.c:658
alloc_skb include/linux/skbuff.h:1313 [inline]
__tcp_send_ack.part.0+0x64/0x720 net/ipv4/tcp_output.c:4206
__tcp_send_ack net/ipv4/tcp_output.c:4238 [inline]
tcp_send_ack+0x82/0xa0 net/ipv4/tcp_output.c:4238
__tcp_cleanup_rbuf+0x278/0x4b0 net/ipv4/tcp.c:1492
tcp_recvmsg_locked+0x114e/0x24c0 net/ipv4/tcp.c:2548
tcp_recvmsg+0x12e/0x680 net/ipv4/tcp.c:2578
inet_recvmsg+0x12b/0x6a0 net/ipv4/af_inet.c:883
sock_recvmsg_nosec net/socket.c:1046 [inline]
sock_recvmsg+0x1b2/0x250 net/socket.c:1068
sock_read_iter+0x2c7/0x3c0 net/socket.c:1138
page last free pid 5111 tgid 5111 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1141 [inline]
free_unref_page_prepare+0x527/0xb10 mm/page_alloc.c:2347
free_unref_page+0x33/0x3c0 mm/page_alloc.c:2487
skb_free_frag include/linux/skbuff.h:3336 [inline]
skb_free_head+0xa6/0x1e0 net/core/skbuff.c:1106
skb_release_data+0x76c/0x990 net/core/skbuff.c:1136
skb_release_all net/core/skbuff.c:1202 [inline]
__kfree_skb net/core/skbuff.c:1216 [inline]
skb_attempt_defer_free+0x3be/0x580 net/core/skbuff.c:7016
tcp_eat_recv_skb net/ipv4/tcp.c:1513 [inline]
tcp_recvmsg_locked+0x10dd/0x24c0 net/ipv4/tcp.c:2532
tcp_recvmsg+0x12e/0x680 net/ipv4/tcp.c:2578
inet_recvmsg+0x12b/0x6a0 net/ipv4/af_inet.c:883
sock_recvmsg_nosec net/socket.c:1046 [inline]
sock_recvmsg+0x1b2/0x250 net/socket.c:1068
sock_read_iter+0x2c7/0x3c0 net/socket.c:1138
call_read_iter include/linux/fs.h:2104 [inline]
new_sync_read fs/read_write.c:395 [inline]
vfs_read+0x9fd/0xb80 fs/read_write.c:476
ksys_read+0x1f8/0x260 fs/read_write.c:619
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcf/0x260 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff888029a1fd80: fb fb fb fb fb fb fc fc fc fc fc fc fc fc fc fc
ffff888029a1fe00: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888029a1fe80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
^
ffff888029a1ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff888029a1ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 10 06 adc %al,(%rsi)
2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi
6: 10 07 adc %al,(%rdi)
8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi
c: 10 08 adc %cl,(%rax)
e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi
1e: 00 51 52 add %dl,0x52(%rcx)
21: 55 push %rbp
22: 89 e5 mov %esp,%ebp
24: 0f 34 sysenter
26: cd 80 int $0x80
* 28: 5d pop %rbp <-- trapping instruction
29: 5a pop %rdx
2a: 59 pop %rcx
2b: c3 ret
2c: 90 nop
2d: 90 nop
2e: 90 nop
2f: 90 nop
30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi
37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi

---
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