KASAN: double-free or invalid-free in skb_free_head

[syzbot]

Hello,

syzkaller hit the following crash on
f3b5ad89de16f5d42e8ad36fbdf85f705c1ae051
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


==================================================================
BUG: KASAN: double-free or invalid-free in skb_free_head+0x74/0xb0
net/core/skbuff.c:550

CPU: 0 PID: 3142 Comm: sshd Not tainted 4.15.0-rc3+ #225
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
print_address_description+0x73/0x250 mm/kasan/report.c:252
kasan_report_double_free+0x55/0x80 mm/kasan/report.c:333
kasan_slab_free+0xa3/0xc0 mm/kasan/kasan.c:514
__cache_free mm/slab.c:3488 [inline]
kfree+0xca/0x250 mm/slab.c:3803
skb_free_head+0x74/0xb0 net/core/skbuff.c:550
skb_release_data+0x58c/0x790 net/core/skbuff.c:570
skb_release_all+0x4a/0x60 net/core/skbuff.c:627
__kfree_skb net/core/skbuff.c:641 [inline]
consume_skb+0x153/0x490 net/core/skbuff.c:701
__dev_kfree_skb_any+0x85/0xa0 net/core/dev.c:2515
dev_consume_skb_any include/linux/netdevice.h:3276 [inline]
free_old_xmit_skbs.isra.28+0x15a/0x2c0 drivers/net/virtio_net.c:1167
start_xmit+0x1b9/0x1650 drivers/net/virtio_net.c:1314
__netdev_start_xmit include/linux/netdevice.h:4042 [inline]
netdev_start_xmit include/linux/netdevice.h:4051 [inline]
xmit_one net/core/dev.c:2991 [inline]
dev_hard_start_xmit+0x248/0xac0 net/core/dev.c:3007
sch_direct_xmit+0x31d/0x6d0 net/sched/sch_generic.c:187
__dev_xmit_skb net/core/dev.c:3189 [inline]
__dev_queue_xmit+0x16f4/0x2070 net/core/dev.c:3456
dev_queue_xmit+0x17/0x20 net/core/dev.c:3521
neigh_hh_output include/net/neighbour.h:472 [inline]
neigh_output include/net/neighbour.h:480 [inline]
ip_finish_output2+0xece/0x1460 net/ipv4/ip_output.c:229
ip_finish_output+0x85e/0xd10 net/ipv4/ip_output.c:317
NF_HOOK_COND include/linux/netfilter.h:239 [inline]
ip_output+0x1cc/0x860 net/ipv4/ip_output.c:405
dst_output include/net/dst.h:460 [inline]
ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124
ip_queue_xmit+0x8c6/0x18e0 net/ipv4/ip_output.c:504
tcp_transmit_skb+0x1b12/0x38b0 net/ipv4/tcp_output.c:1176
tcp_write_xmit+0x680/0x5190 net/ipv4/tcp_output.c:2367
__tcp_push_pending_frames+0xa0/0x250 net/ipv4/tcp_output.c:2543
tcp_push+0x538/0x770 net/ipv4/tcp.c:730
tcp_sendmsg_locked+0x2663/0x3b30 net/ipv4/tcp.c:1424
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1461
inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
sock_sendmsg_nosec net/socket.c:636 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:646
sock_write_iter+0x31a/0x5d0 net/socket.c:915
call_write_iter include/linux/fs.h:1772 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x684/0x970 fs/read_write.c:482
vfs_write+0x189/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
entry_SYSCALL_64_fastpath+0x1f/0x96
RIP: 0033:0x7f7a61d22370
RSP: 002b:00007ffc93b90b98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000563815b397d0 RCX: 00007f7a61d22370
RDX: 0000000000000038 RSI: 0000563815b2b460 RDI: 0000000000000003
RBP: 00007ffc93b90b20 R08: 0000000000000001 R09: 0101010101010101
R10: 0000000000000008 R11: 0000000000000246 R12: 0000000000000040
R13: 000000000000005e R14: 0000563815b304e0 R15: 00007ffc93b90b70

Allocated by task 3142:
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
__do_kmalloc_node mm/slab.c:3672 [inline]
__kmalloc_node_track_caller+0x47/0x70 mm/slab.c:3686
__kmalloc_reserve.isra.41+0x41/0xd0 net/core/skbuff.c:137
__alloc_skb+0x13b/0x780 net/core/skbuff.c:205
alloc_skb_fclone include/linux/skbuff.h:1025 [inline]
sk_stream_alloc_skb+0x11d/0x900 net/ipv4/tcp.c:870
tcp_sendmsg_locked+0x1341/0x3b30 net/ipv4/tcp.c:1299
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1461
inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
sock_sendmsg_nosec net/socket.c:636 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:646
sock_write_iter+0x31a/0x5d0 net/socket.c:915
call_write_iter include/linux/fs.h:1772 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x684/0x970 fs/read_write.c:482
vfs_write+0x189/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
entry_SYSCALL_64_fastpath+0x1f/0x96

Freed by task 3142:
save_stack+0x43/0xd0 mm/kasan/kasan.c:447
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3488 [inline]
kfree+0xca/0x250 mm/slab.c:3803
skb_free_head+0x74/0xb0 net/core/skbuff.c:550
skb_release_data+0x58c/0x790 net/core/skbuff.c:570
skb_release_all+0x4a/0x60 net/core/skbuff.c:627
__kfree_skb net/core/skbuff.c:641 [inline]
consume_skb+0x153/0x490 net/core/skbuff.c:701
__dev_kfree_skb_any+0x85/0xa0 net/core/dev.c:2515
dev_consume_skb_any include/linux/netdevice.h:3276 [inline]
free_old_xmit_skbs.isra.28+0x15a/0x2c0 drivers/net/virtio_net.c:1167
start_xmit+0x1b9/0x1650 drivers/net/virtio_net.c:1314
__netdev_start_xmit include/linux/netdevice.h:4042 [inline]
netdev_start_xmit include/linux/netdevice.h:4051 [inline]
xmit_one net/core/dev.c:2991 [inline]
dev_hard_start_xmit+0x248/0xac0 net/core/dev.c:3007
sch_direct_xmit+0x31d/0x6d0 net/sched/sch_generic.c:187
__dev_xmit_skb net/core/dev.c:3189 [inline]
__dev_queue_xmit+0x16f4/0x2070 net/core/dev.c:3456
dev_queue_xmit+0x17/0x20 net/core/dev.c:3521
neigh_hh_output include/net/neighbour.h:472 [inline]
neigh_output include/net/neighbour.h:480 [inline]
ip_finish_output2+0xece/0x1460 net/ipv4/ip_output.c:229
ip_finish_output+0x85e/0xd10 net/ipv4/ip_output.c:317
NF_HOOK_COND include/linux/netfilter.h:239 [inline]
ip_output+0x1cc/0x860 net/ipv4/ip_output.c:405
dst_output include/net/dst.h:460 [inline]
ip_local_out+0x95/0x160 net/ipv4/ip_output.c:124
ip_queue_xmit+0x8c6/0x18e0 net/ipv4/ip_output.c:504
tcp_transmit_skb+0x1b12/0x38b0 net/ipv4/tcp_output.c:1176
tcp_write_xmit+0x680/0x5190 net/ipv4/tcp_output.c:2367
__tcp_push_pending_frames+0xa0/0x250 net/ipv4/tcp_output.c:2543
tcp_push+0x538/0x770 net/ipv4/tcp.c:730
tcp_sendmsg_locked+0x2663/0x3b30 net/ipv4/tcp.c:1424
tcp_sendmsg+0x2f/0x50 net/ipv4/tcp.c:1461
inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763
sock_sendmsg_nosec net/socket.c:636 [inline]
sock_sendmsg+0xca/0x110 net/socket.c:646
sock_write_iter+0x31a/0x5d0 net/socket.c:915
call_write_iter include/linux/fs.h:1772 [inline]
new_sync_write fs/read_write.c:469 [inline]
__vfs_write+0x684/0x970 fs/read_write.c:482
vfs_write+0x189/0x510 fs/read_write.c:544
SYSC_write fs/read_write.c:589 [inline]
SyS_write+0xef/0x220 fs/read_write.c:581
entry_SYSCALL_64_fastpath+0x1f/0x96

The buggy address belongs to the object at ffff8801c719cdc0
which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 0 bytes inside of
1024-byte region [ffff8801c719cdc0, ffff8801c719d1c0)
The buggy address belongs to the page:
page:0000000009b6561b count:1 mapcount:0 mapping:00000000749a03ca index:0x0
compound_mapcount: 0
flags: 0x2fffc0000008100(slab|head)
raw: 02fffc0000008100 ffff8801c719c040 0000000000000000 0000000100000007
raw: ffffea00071edf20 ffffea00071c9220 ffff8801db000ac0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801c719cc80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8801c719cd00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ffff8801c719cd80: fb fb fb fb fb fb fb fb fb fb fb fb 00 00 00 00
^
ffff8801c719ce00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8801c719ce80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================


---
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[Eric Biggers]

This crash is no longer occurring, and the reproducer actually used AF_ALG with
"pcrypt", so this was probably the slab corruption fixed by commit
d76c68109f37c:

#syz fix: crypto: pcrypt - fix freeing pcrypt instances

- Eric