KASAN: use-after-free Read in kfree_skb (2)

From: syzbot
Date: Mon Dec 10 2018 - 14:11:07 EST

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Hello,

syzbot found the following crash on:

HEAD commit: 40e020c129cf Linux 4.20-rc6
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1254ca7d400000
kernel config: https://syzkaller.appspot.com/x/.config?x=c8970c89a0efbb23
dashboard link: https://syzkaller.appspot.com/bug?extid=eae585ba2cc2752d3704
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17473c15400000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=169af3f5400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+eae585ba2cc2752d3704@xxxxxxxxxxxxxxxxxxxxxxxxx

Started in network mode
Own node identity 00000000000000000000000000000001, cluster identity 4711
New replicast peer: fe80:0000:0000:0000:0000:0000:0000:00aa
==================================================================
BUG: KASAN: use-after-free in atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
BUG: KASAN: use-after-free in refcount_read include/linux/refcount.h:43 [inline]
BUG: KASAN: use-after-free in skb_unref include/linux/skbuff.h:969 [inline]
BUG: KASAN: use-after-free in kfree_skb+0xb7/0x580 net/core/skbuff.c:655
Read of size 4 at addr ffff8881b387eae4 by task syz-executor306/5992

CPU: 1 PID: 5992 Comm: syz-executor306 Not tainted 4.20.0-rc6+ #370
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x244/0x39d lib/dump_stack.c:113
print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
refcount_read include/linux/refcount.h:43 [inline]
skb_unref include/linux/skbuff.h:969 [inline]
kfree_skb+0xb7/0x580 net/core/skbuff.c:655
tipc_udp_send_msg+0x5a6/0x670 net/tipc/udp_media.c:249
tipc_bearer_xmit_skb+0x171/0x350 net/tipc/bearer.c:502
tipc_enable_bearer+0xc5e/0xf10 net/tipc/bearer.c:327
__tipc_nl_bearer_enable+0x37c/0x4a0 net/tipc/bearer.c:897
tipc_nl_bearer_enable+0x22/0x30 net/tipc/bearer.c:905
genl_family_rcv_msg+0x8a7/0x11a0 net/netlink/genetlink.c:601
genl_rcv_msg+0xc6/0x168 net/netlink/genetlink.c:626
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
genl_rcv+0x28/0x40 net/netlink/genetlink.c:637
netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:631
___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
__sys_sendmsg+0x11d/0x280 net/socket.c:2154
__do_sys_sendmsg net/socket.c:2163 [inline]
__se_sys_sendmsg net/socket.c:2161 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4446f9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 1b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe705f7a98 EFLAGS: 00000213 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 00000000004446f9
RDX: 0000000000000000 RSI: 0000000020000700 RDI: 0000000000000003
RBP: 00000000006cf018 R08: 0000000000000000 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000213 R12: 00000000004023a0
R13: 0000000000402430 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 5992:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
kmem_cache_alloc_node+0x144/0x730 mm/slab.c:3644
__alloc_skb+0x119/0x770 net/core/skbuff.c:193
__pskb_copy_fclone+0x16b/0xeb0 net/core/skbuff.c:1385
__pskb_copy include/linux/skbuff.h:1053 [inline]
pskb_copy include/linux/skbuff.h:2915 [inline]
tipc_udp_send_msg+0x44e/0x670 net/tipc/udp_media.c:241
tipc_bearer_xmit_skb+0x171/0x350 net/tipc/bearer.c:502
tipc_enable_bearer+0xc5e/0xf10 net/tipc/bearer.c:327
__tipc_nl_bearer_enable+0x37c/0x4a0 net/tipc/bearer.c:897
tipc_nl_bearer_enable+0x22/0x30 net/tipc/bearer.c:905
genl_family_rcv_msg+0x8a7/0x11a0 net/netlink/genetlink.c:601
genl_rcv_msg+0xc6/0x168 net/netlink/genetlink.c:626
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
genl_rcv+0x28/0x40 net/netlink/genetlink.c:637
netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:631
___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
__sys_sendmsg+0x11d/0x280 net/socket.c:2154
__do_sys_sendmsg net/socket.c:2163 [inline]
__se_sys_sendmsg net/socket.c:2161 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 5992:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kmem_cache_free+0x83/0x290 mm/slab.c:3760
kfree_skbmem+0x154/0x230 net/core/skbuff.c:582
__kfree_skb net/core/skbuff.c:642 [inline]
kfree_skb+0x1c3/0x580 net/core/skbuff.c:659
tipc_udp_xmit.isra.14+0x420/0xef0 net/tipc/udp_media.c:207
tipc_udp_send_msg+0x398/0x670 net/tipc/udp_media.c:247
tipc_bearer_xmit_skb+0x171/0x350 net/tipc/bearer.c:502
tipc_enable_bearer+0xc5e/0xf10 net/tipc/bearer.c:327
__tipc_nl_bearer_enable+0x37c/0x4a0 net/tipc/bearer.c:897
tipc_nl_bearer_enable+0x22/0x30 net/tipc/bearer.c:905
genl_family_rcv_msg+0x8a7/0x11a0 net/netlink/genetlink.c:601
genl_rcv_msg+0xc6/0x168 net/netlink/genetlink.c:626
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
genl_rcv+0x28/0x40 net/netlink/genetlink.c:637
netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:631
___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
__sys_sendmsg+0x11d/0x280 net/socket.c:2154
__do_sys_sendmsg net/socket.c:2163 [inline]
__se_sys_sendmsg net/socket.c:2161 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8881b387ea00
which belongs to the cache skbuff_head_cache of size 232
The buggy address is located 228 bytes inside of
232-byte region [ffff8881b387ea00, ffff8881b387eae8)
The buggy address belongs to the page:
page:ffffea0006ce1f80 count:1 mapcount:0 mapping:ffff8881d9be8780 index:0x0
flags: 0x2fffc0000000200(slab)
raw: 02fffc0000000200 ffffea000744d908 ffff8881d9bda048 ffff8881d9be8780
raw: 0000000000000000 ffff8881b387e000 000000010000000c 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881b387e980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff8881b387ea00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

ffff8881b387ea80: fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc

^
ffff8881b387eb00: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
ffff8881b387eb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
==================================================================
BUG: KASAN: double-free or invalid-free in skb_free_head+0x99/0xc0 net/core/skbuff.c:550

CPU: 1 PID: 5992 Comm: syz-executor306 Tainted: G B 4.20.0-rc6+ #370
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
<IRQ>
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x244/0x39d lib/dump_stack.c:113
print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
kasan_report_invalid_free+0x64/0xa0 mm/kasan/report.c:336
__kasan_slab_free+0x13a/0x150 mm/kasan/kasan.c:501
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3817
skb_free_head+0x99/0xc0 net/core/skbuff.c:550
skb_release_data+0x70c/0x9a0 net/core/skbuff.c:570
skb_release_all+0x4a/0x60 net/core/skbuff.c:627
__kfree_skb net/core/skbuff.c:641 [inline]
kfree_skb+0x1bb/0x580 net/core/skbuff.c:659
tipc_udp_send_msg+0x5a6/0x670 net/tipc/udp_media.c:249
tipc_bearer_xmit_skb+0x171/0x350 net/tipc/bearer.c:502
tipc_disc_timeout+0xb2b/0xfc0 net/tipc/discover.c:332
call_timer_fn+0x272/0x920 kernel/time/timer.c:1326
expire_timers kernel/time/timer.c:1363 [inline]
__run_timers+0x7e5/0xc70 kernel/time/timer.c:1682
run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1695
__do_softirq+0x308/0xb7e kernel/softirq.c:292
invoke_softirq kernel/softirq.c:373 [inline]
irq_exit+0x17f/0x1c0 kernel/softirq.c:413
exiting_irq arch/x86/include/asm/apic.h:536 [inline]
smp_apic_timer_interrupt+0x1cb/0x760 arch/x86/kernel/apic/apic.c:1061
apic_timer_interrupt+0xf/0x20 arch/x86/entry/entry_64.S:807
</IRQ>
RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:761 [inline]
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:160 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xaf/0xd0 kernel/locking/spinlock.c:184
Code: f0 00 52 89 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 28 48 83 3d 18 ef 76 01 00 74 15 48 89 df 57 9d <0f> 1f 44 00 00 eb ad e8 1c 6b 25 f9 eb bb 0f 0b 0f 0b e8 9a d7 e7
RSP: 0018:ffff8881b2ae6de8 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff13
RAX: dffffc0000000000 RBX: 0000000000000286 RCX: ffffffff8185acea
RDX: 1ffffffff12a401e RSI: ffffffff8185ad04 RDI: 0000000000000286
RBP: ffff8881b2ae6df8 R08: ffff8881b3888240 R09: fffffbfff12c7248
R10: fffffbfff12c7248 R11: ffffffff89639243 R12: ffffffff89639240
R13: 0000000000000000 R14: ffff8881b387eae4 R15: ffff8881b387eae4
spin_unlock_irqrestore include/linux/spinlock.h:384 [inline]
kasan_end_report+0x32/0x4f mm/kasan/report.c:178
kasan_report_error mm/kasan/report.c:359 [inline]
kasan_report.cold.8+0x76/0x309 mm/kasan/report.c:412
check_memory_region_inline mm/kasan/kasan.c:260 [inline]
check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
kasan_check_read+0x11/0x20 mm/kasan/kasan.c:272
atomic_read include/asm-generic/atomic-instrumented.h:21 [inline]
refcount_read include/linux/refcount.h:43 [inline]
skb_unref include/linux/skbuff.h:969 [inline]
kfree_skb+0xb7/0x580 net/core/skbuff.c:655
tipc_udp_send_msg+0x5a6/0x670 net/tipc/udp_media.c:249
tipc_bearer_xmit_skb+0x171/0x350 net/tipc/bearer.c:502
tipc_enable_bearer+0xc5e/0xf10 net/tipc/bearer.c:327
__tipc_nl_bearer_enable+0x37c/0x4a0 net/tipc/bearer.c:897
tipc_nl_bearer_enable+0x22/0x30 net/tipc/bearer.c:905
genl_family_rcv_msg+0x8a7/0x11a0 net/netlink/genetlink.c:601
genl_rcv_msg+0xc6/0x168 net/netlink/genetlink.c:626
netlink_rcv_skb+0x172/0x440 net/netlink/af_netlink.c:2477
genl_rcv+0x28/0x40 net/netlink/genetlink.c:637
netlink_unicast_kernel net/netlink/af_netlink.c:1310 [inline]
netlink_unicast+0x5a5/0x760 net/netlink/af_netlink.c:1336
netlink_sendmsg+0xa18/0xfc0 net/netlink/af_netlink.c:1917
sock_sendmsg_nosec net/socket.c:621 [inline]
sock_sendmsg+0xd5/0x120 net/socket.c:631
___sys_sendmsg+0x7fd/0x930 net/socket.c:2116
__sys_sendmsg+0x11d/0x280 net/socket.c:2154
__do_sys_sendmsg net/socket.c:2163 [inline]
__se_sys_sendmsg net/socket.c:2161 [inline]
__x64_sys_sendmsg+0x78/0xb0 net/socket.c:2161
do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4446f9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 1b d8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffe705f7a98 EFLAGS: 00000213 ORIG_RAX: 000000000000002e
RAX: ffffffffffffffda RBX: 00000000004002e0 RCX: 00000000004446f9
RDX: 0000000000000000 RSI: 0000000020000700 RDI: 0000000000000003
RBP: 00000000006cf018 R08: 0000000000000000 R09: 00000000004002e0
R10: 0000000000000000 R11: 0000000000000213 R12: 00000000004023a0
R13: 0000000000402430 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 5992:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
__do_kmalloc_node mm/slab.c:3684 [inline]
__kmalloc_node_track_caller+0x50/0x70 mm/slab.c:3698
__kmalloc_reserve.isra.40+0x41/0xe0 net/core/skbuff.c:137
__alloc_skb+0x155/0x770 net/core/skbuff.c:205
__pskb_copy_fclone+0x16b/0xeb0 net/core/skbuff.c:1385
__pskb_copy include/linux/skbuff.h:1053 [inline]
pskb_copy include/linux/skbuff.h:2915 [inline]
tipc_udp_send_msg+0x44e/0x670 net/tipc/udp_media.c:241
tipc_bearer_xmit_skb+0x171/0x350 net/tipc/bearer.c:502
tipc_disc_timeout+0xb2b/0xfc0 net/tipc/discover.c:332
call_timer_fn+0x272/0x920 kernel/time/timer.c:1326
expire_timers kernel/time/timer.c:1363 [inline]
__run_timers+0x7e5/0xc70 kernel/time/timer.c:1682
run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1695
__do_softirq+0x308/0xb7e kernel/softirq.c:292

Freed by task 5992:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xcf/0x230 mm/slab.c:3817
skb_free_head+0x99/0xc0 net/core/skbuff.c:550
skb_release_data+0x70c/0x9a0 net/core/skbuff.c:570
skb_release_all+0x4a/0x60 net/core/skbuff.c:627
__kfree_skb net/core/skbuff.c:641 [inline]
kfree_skb+0x1bb/0x580 net/core/skbuff.c:659
tipc_udp_xmit.isra.14+0x420/0xef0 net/tipc/udp_media.c:207
tipc_udp_send_msg+0x398/0x670 net/tipc/udp_media.c:247
tipc_bearer_xmit_skb+0x171/0x350 net/tipc/bearer.c:502
tipc_disc_timeout+0xb2b/0xfc0 net/tipc/discover.c:332
call_timer_fn+0x272/0x920 kernel/time/timer.c:1326
expire_timers kernel/time/timer.c:1363 [inline]
__run_timers+0x7e5/0xc70 kernel/time/timer.c:1682
run_timer_softirq+0x52/0xb0 kernel/time/timer.c:1695
__do_softirq+0x308/0xb7e kernel/softirq.c:292

The buggy address belongs to the object at ffff8881c393e480
which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 0 bytes inside of
1024-byte region [ffff8881c393e480, ffff8881c393e880)
The buggy address belongs to the page:
page:ffffea00070e4f80 count:1 mapcount:0 mapping:ffff8881da800ac0 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea00070f3b88 ffffea000709b388 ffff8881da800ac0
raw: 0000000000000000 ffff8881c393e000 0000000100000007 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8881c393e380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881c393e400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc

ffff8881c393e480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb

^
ffff8881c393e500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff8881c393e580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
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syzbot can test patches for this bug, for details see:
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Next message: Stephen Boyd: "Re: [PATCH V2] clk: tegra: Return the exact clock rate from clk_round_rate"
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