Re: BUG: KASAN: use-after-free in udp_lib_get_port

[Eric Dumazet]

On Wed, 2016-10-19 at 23:01 +0800, Baozeng Ding wrote:
> Hello all,
> I have got some similar bugs again((on Oct 7 commit 
> d1f5323370fceaed43a7ee38f4c7bfc7e70f28d0):


Thanks for the reports, but please there is no need to send duplicates.

I have an idea of the problem, will send a patch asap, after a bit of
sleep.

Re: BUG: KASAN: use-after-free in udp_lib_get_port

[Baozeng Ding]

Hello all,
I have got some similar bugs again((on Oct 7 commit 
d1f5323370fceaed43a7ee38f4c7bfc7e70f28d0):

BUG: KASAN: use-after-free in udp_lib_get_port+0x1573/0x1860 at addr 
88002f163c60
Write of size 8 by task syz-executor/13510
CPU: 2 PID: 13510 Comm: syz-executor Not tainted 4.8.0+ #41
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
 880034ea7a68 829f835b 88002f488b40 88002f163c40
 88002f164350 88003178154a 880034ea7a90 8174d3cc
 880034ea7b20 88002f163c00 88002f488b40 880034ea7b10
Call Trace:
 [] dump_stack+0xb3/0x118 /lib/dump_stack.c:15
 [] kasan_object_err+0x1c/0x70 /mm/kasan/report.c:156
 [< inline >] print_address_description /mm/kasan/report.c:194
 [] kasan_report_error+0x1f6/0x4d0 /mm/kasan/report.c:283
 [< inline >] kasan_report /mm/kasan/report.c:303
 [] __asan_report_store8_noabort+0x3e/0x40 
/mm/kasan/report.c:329
 [< inline >] hlist_add_head_rcu /./include/linux/rculist.h:487
 [] udp_lib_get_port+0x1573/0x1860 /net/ipv4/udp.c:345
 [] udp_v4_get_port+0x139/0x180 /net/ipv4/udp.c:392
 [] inet_autobind+0xaa/0x180 /net/ipv4/af_inet.c:181
 [] inet_dgram_connect+0x131/0x1f0 /net/ipv4/af_inet.c:528
 [] SYSC_connect+0x23e/0x2e0 /net/socket.c:1533
 [] SyS_connect+0x24/0x30 /net/socket.c:1514
 [] entry_SYSCALL_64_fastpath+0x23/0xc6
Object at 88002f163c40, in cache UDPv6 size: 1496
Allocated:
PID = 13255
 [ 1773.470431] [] save_stack_trace+0x16/0x20
 [ 1773.470431] [] save_stack+0x46/0xd0
 [ 1773.470431] [] kasan_kmalloc+0xad/0xe0
 [ 1773.470431] [] kasan_slab_alloc+0x12/0x20
 [ 1773.470431] [< inline >] slab_post_alloc_hook /mm/slab.h:417
 [ 1773.470431] [< inline >] slab_alloc_node /mm/slub.c:2708
 [ 1773.470431] [< inline >] slab_alloc /mm/slub.c:2716
 [ 1773.470431] [] kmem_cache_alloc+0xc8/0x2b0 /mm/slub.c:2721
 [ 1773.470431] [] sk_prot_alloc+0x69/0x2b0 
/net/core/sock.c:1326
 [ 1773.470431] [] sk_alloc+0x38/0xae0 /net/core/sock.c:1388
 [ 1773.470431] [] inet6_create+0x2d7/0x1000 
/net/ipv6/af_inet6.c:182
 [ 1773.470431] [] __sock_create+0x37b/0x640 
/net/socket.c:1153
 [ 1773.470431] [< inline >] sock_create /net/socket.c:1193
 [ 1773.470431] [< inline >] SYSC_socket /net/socket.c:1223
 [ 1773.470431] [] SyS_socket+0xef/0x1b0 /net/socket.c:1203
 [ 1773.470431] [] entry_SYSCALL_64_fastpath+0x23/0xc6
Freed:
PID = 13261
 [ 1773.470431] [] save_stack_trace+0x16/0x20
 [ 1773.470431] [] save_stack+0x46/0xd0
 [ 1773.470431] [] kasan_slab_free+0x71/0xb0
 [ 1773.470431] [< inline >] slab_free_hook /mm/slub.c:1352
 [ 1773.470431] [< inline >] slab_free_freelist_hook /mm/slub.c:1374
 [ 1773.470431] [< inline >] slab_free /mm/slub.c:2951
 [ 1773.470431] [] kmem_cache_free+0xc8/0x330 /mm/slub.c:2973
 [ 1773.470431] [< inline >] sk_prot_free /net/core/sock.c:1369
 [ 1773.470431] [] __sk_destruct+0x32b/0x4f0 
/net/core/sock.c:1444
 [ 1773.470431] [] sk_destruct+0x44/0x80 /net/core/sock.c:1452
 [ 1773.470431] [] __sk_free+0x53/0x220 /net/core/sock.c:1460
 [ 1773.470431] [] sk_free+0x23/0x30 /net/core/sock.c:1471
 [ 1773.470431] [] sk_common_release+0x28c/0x3e0 
/./include/net/sock.h:1589
 [ 1773.470431] [] udp_lib_close+0x15/0x20 
/./include/net/udp.h:203
 [ 1773.470431] [] inet_release+0xed/0x1c0 
/net/ipv4/af_inet.c:415
 [ 1773.470431] [] inet6_release+0x5a/0x80 
/net/ipv6/af_inet6.c:424
 [ 1773.470431] [] sock_release+0x8d/0x1d0 /net/socket.c:570
 [ 1773.470431] [] sock_close+0x16/0x20 /net/socket.c:1017
 [ 1773.470431] [] __fput+0x28c/0x780 /fs/file_table.c:208
 [ 1773.470431] [] fput+0x15/0x20 /fs/file_table.c:244
 [ 1773.470431] [] task_work_run+0xf9/0x170
 [ 1773.470431] [] do_exit+0x85e/0x2a00
 [ 1773.470431] [] do_group_exit+0x108/0x330
 [ 1773.470431] [] get_signal+0x617/0x17a0 
/kernel/signal.c:2307
 [ 1773.470431] [] do_signal+0x7f/0x18f0
 [ 1773.470431] [] exit_to_usermode_loop+0xbf/0x150 
/arch/x86/entry/common.c:156
 [ 1773.470431] [< inline >] prepare_exit_to_usermode 
/arch/x86/entry/common.c:190
 [ 1773.470431] [] syscall_return_slowpath+0x1a0/0x1e0 
/arch/x86/entry/common.c:259
 [ 1773.470431] [] entry_SYSCALL_64_fastpath+0xc4/0xc6
Memory state around the buggy address:
 88002f163b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 88002f163b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>88002f163c00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
   ^
 88002f163c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 88002f163d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==
Disabling lock debugging due to kernel taint
==
BUG: KASAN: use-after-free in udp_lib_unhash+0x593/0x660 at addr 
88002f163c60
Write of size 8 by task syz-executor/13522

Re: BUG: KASAN: use-after-free in udp_lib_get_port

[Baozeng Ding]

Hello all,
I hit some similiar bugs again:

BUG: KASAN: use-after-free in udp_lib_get_port+0x1573/0x1860 at addr 
88002f163c60
Write of size 8 by task syz-executor/13510
CPU: 2 PID: 13510 Comm: syz-executor Not tainted 4.8.0+ #41
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
 880034ea7a68 829f835b 88002f488b40 88002f163c40
 88002f164350 88003178154a 880034ea7a90 8174d3cc
 880034ea7b20 88002f163c00 88002f488b40 880034ea7b10
Call Trace:
 [] dump_stack+0xb3/0x118 /lib/dump_stack.c:15
 [] kasan_object_err+0x1c/0x70 /mm/kasan/report.c:156
 [< inline >] print_address_description /mm/kasan/report.c:194
 [] kasan_report_error+0x1f6/0x4d0 /mm/kasan/report.c:283
 [< inline >] kasan_report /mm/kasan/report.c:303
 [] __asan_report_store8_noabort+0x3e/0x40 
/mm/kasan/report.c:329
 [< inline >] hlist_add_head_rcu /./include/linux/rculist.h:487
 [] udp_lib_get_port+0x1573/0x1860 /net/ipv4/udp.c:345
 [] udp_v4_get_port+0x139/0x180 /net/ipv4/udp.c:392
 [] inet_autobind+0xaa/0x180 /net/ipv4/af_inet.c:181
 [] inet_dgram_connect+0x131/0x1f0 /net/ipv4/af_inet.c:528
 [] SYSC_connect+0x23e/0x2e0 /net/socket.c:1533
 [] SyS_connect+0x24/0x30 /net/socket.c:1514
 [] entry_SYSCALL_64_fastpath+0x23/0xc6
Object at 88002f163c40, in cache UDPv6 size: 1496
Allocated:
PID = 13255
 [ 1773.470431] [] save_stack_trace+0x16/0x20
 [ 1773.470431] [] save_stack+0x46/0xd0
 [ 1773.470431] [] kasan_kmalloc+0xad/0xe0
 [ 1773.470431] [] kasan_slab_alloc+0x12/0x20
 [ 1773.470431] [< inline >] slab_post_alloc_hook /mm/slab.h:417
 [ 1773.470431] [< inline >] slab_alloc_node /mm/slub.c:2708
 [ 1773.470431] [< inline >] slab_alloc /mm/slub.c:2716
 [ 1773.470431] [] kmem_cache_alloc+0xc8/0x2b0 /mm/slub.c:2721
 [ 1773.470431] [] sk_prot_alloc+0x69/0x2b0 
/net/core/sock.c:1326
 [ 1773.470431] [] sk_alloc+0x38/0xae0 /net/core/sock.c:1388
 [ 1773.470431] [] inet6_create+0x2d7/0x1000 
/net/ipv6/af_inet6.c:182
 [ 1773.470431] [] __sock_create+0x37b/0x640 
/net/socket.c:1153
 [ 1773.470431] [< inline >] sock_create /net/socket.c:1193
 [ 1773.470431] [< inline >] SYSC_socket /net/socket.c:1223
 [ 1773.470431] [] SyS_socket+0xef/0x1b0 /net/socket.c:1203
 [ 1773.470431] [] entry_SYSCALL_64_fastpath+0x23/0xc6
Freed:
PID = 13261
 [ 1773.470431] [] save_stack_trace+0x16/0x20
 [ 1773.470431] [] save_stack+0x46/0xd0
 [ 1773.470431] [] kasan_slab_free+0x71/0xb0
 [ 1773.470431] [< inline >] slab_free_hook /mm/slub.c:1352
 [ 1773.470431] [< inline >] slab_free_freelist_hook /mm/slub.c:1374
 [ 1773.470431] [< inline >] slab_free /mm/slub.c:2951
 [ 1773.470431] [] kmem_cache_free+0xc8/0x330 /mm/slub.c:2973
 [ 1773.470431] [< inline >] sk_prot_free /net/core/sock.c:1369
 [ 1773.470431] [] __sk_destruct+0x32b/0x4f0 
/net/core/sock.c:1444
 [ 1773.470431] [] sk_destruct+0x44/0x80 /net/core/sock.c:1452
 [ 1773.470431] [] __sk_free+0x53/0x220 /net/core/sock.c:1460
 [ 1773.470431] [] sk_free+0x23/0x30 /net/core/sock.c:1471
 [ 1773.470431] [] sk_common_release+0x28c/0x3e0 
/./include/net/sock.h:1589
 [ 1773.470431] [] udp_lib_close+0x15/0x20 
/./include/net/udp.h:203
 [ 1773.470431] [] inet_release+0xed/0x1c0 
/net/ipv4/af_inet.c:415
 [ 1773.470431] [] inet6_release+0x5a/0x80 
/net/ipv6/af_inet6.c:424
 [ 1773.470431] [] sock_release+0x8d/0x1d0 /net/socket.c:570
 [ 1773.470431] [] sock_close+0x16/0x20 /net/socket.c:1017
 [ 1773.470431] [] __fput+0x28c/0x780 /fs/file_table.c:208
 [ 1773.470431] [] fput+0x15/0x20 /fs/file_table.c:244
 [ 1773.470431] [] task_work_run+0xf9/0x170
 [ 1773.470431] [] do_exit+0x85e/0x2a00
 [ 1773.470431] [] do_group_exit+0x108/0x330
 [ 1773.470431] [] get_signal+0x617/0x17a0 
/kernel/signal.c:2307
 [ 1773.470431] [] do_signal+0x7f/0x18f0
 [ 1773.470431] [] exit_to_usermode_loop+0xbf/0x150 
/arch/x86/entry/common.c:156
 [ 1773.470431] [< inline >] prepare_exit_to_usermode 
/arch/x86/entry/common.c:190
 [ 1773.470431] [] syscall_return_slowpath+0x1a0/0x1e0 
/arch/x86/entry/common.c:259
 [ 1773.470431] [] entry_SYSCALL_64_fastpath+0xc4/0xc6
Memory state around the buggy address:
 88002f163b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 88002f163b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>88002f163c00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
   ^
 88002f163c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 88002f163d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==
Disabling lock debugging due to kernel taint
==
BUG: KASAN: use-after-free in udp_lib_unhash+0x593/0x660 at addr 
88002f163c60
Write of size 8 by task syz-executor/13522
CPU: 1 PID: 13522 Comm: syz-executor Tainted: GB   

Re: BUG: KASAN: use-after-free in udp_lib_get_port

[Cong Wang]

On Sun, Oct 16, 2016 at 6:46 AM, Baozeng Ding  wrote:
> Hello all,
> While running syzkaller fuzzer I have got the following use-after-free
> bug in udp_lib_get_port. The kernel version is 4.8.0+ (on Oct 7 commit 
> d1f5323370fceaed43a7ee38f4c7bfc7e70f28d0). Unfortunately I failed to find a 
> reproducer for it.
>
> BUG: KASAN: use-after-free in udp_lib_get_port+0x1573/0x1860 at addr 
> 88000804cb60
> Write of size 8 by task syz-executor/31190
> CPU: 0 PID: 31190 Comm: syz-executor Not tainted 4.8.0+ #39
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 
> rel-1.8.2-0-g33fbe13 by qemu-project.org 04/01/2014
>  880015ac7a48 829f835b 880032b531c0 88000804cb40
>  88000804d250 880017415a4a 880015ac7a70 8174d3cc
>  880015ac7b00 88000804cb00 880032b531c0 880015ac7af0
> Call Trace:
>  [] dump_stack+0xb3/0x118 lib/dump_stack.c:15
>  [] kasan_object_err+0x1c/0x70 mm/kasan/report.c:156
>  [< inline >] print_address_description mm/kasan/report.c:194
>  [] kasan_report_error+0x1f6/0x4d0 mm/kasan/report.c:283
>  [< inline >] kasan_report mm/kasan/report.c:303
>  [] __asan_report_store8_noabort+0x3e/0x40 
> mm/kasan/report.c:329
>  [< inline >] hlist_add_head_rcu ./include/linux/rculist.h:487
>  [] udp_lib_get_port+0x1573/0x1860 net/ipv4/udp.c:345
>  [] udp_v6_get_port+0xa7/0xd0 net/ipv6/udp.c:106
>  [] inet6_bind+0x89c/0xfb0 net/ipv6/af_inet6.c:384
>  [] SYSC_bind+0x1ea/0x250 net/socket.c:1367
>  [] SyS_bind+0x24/0x30 net/socket.c:1353
>  [] entry_SYSCALL_64_fastpath+0x23/0xc6


We should have a reference to this sock via fd and its sock->sk too,
so I fail to see why it could be freed while we holding this reference.
Maybe a VFS layer bug?

> Object at 88000804cb40, in cache UDPv6 size: 1496
> Allocated:
> PID = 30789
>  [  378.305168] [] save_stack_trace+0x16/0x20
>  [  378.305168] [] save_stack+0x46/0xd0
>  [  378.305168] [] kasan_kmalloc+0xad/0xe0
>  [  378.305168] [] kasan_slab_alloc+0x12/0x20
>  [  378.305168] [< inline >] slab_post_alloc_hook mm/slab.h:417
>  [  378.305168] [< inline >] slab_alloc_node mm/slub.c:2708
>  [  378.305168] [< inline >] slab_alloc mm/slub.c:2716
>  [  378.305168] [] kmem_cache_alloc+0xc8/0x2b0 
> mm/slub.c:2721
>  [  378.305168] [] sk_prot_alloc+0x69/0x2b0 
> net/core/sock.c:1326
>  [  378.305168] [] sk_alloc+0x38/0xae0 net/core/sock.c:1388
>  [  378.305168] [] inet6_create+0x2d7/0x1000 
> net/ipv6/af_inet6.c:182
>  [  378.305168] [] __sock_create+0x37b/0x640 
> net/socket.c:1153
>  [  378.305168] [< inline >] sock_create net/socket.c:1193
>  [  378.305168] [< inline >] SYSC_socket net/socket.c:1223
>  [  378.305168] [] SyS_socket+0xef/0x1b0 net/socket.c:1203
>  [  378.305168] [] entry_SYSCALL_64_fastpath+0x23/0xc6
> Freed:
> PID = 30789
>  [  378.305168] [] save_stack_trace+0x16/0x20
>  [  378.305168] [] save_stack+0x46/0xd0
>  [  378.305168] [] kasan_slab_free+0x71/0xb0
>  [  378.305168] [< inline >] slab_free_hook mm/slub.c:1352
>  [  378.305168] [< inline >] slab_free_freelist_hook mm/slub.c:1374
>  [  378.305168] [< inline >] slab_free mm/slub.c:2951
>  [  378.305168] [] kmem_cache_free+0xc8/0x330 mm/slub.c:2973
>  [  378.305168] [< inline >] sk_prot_free net/core/sock.c:1369
>  [  378.305168] [] __sk_destruct+0x32b/0x4f0 
> net/core/sock.c:1444
>  [  378.305168] [] sk_destruct+0x44/0x80 
> net/core/sock.c:1452
>  [  378.305168] [] __sk_free+0x53/0x220 net/core/sock.c:1460
>  [  378.305168] [] sk_free+0x23/0x30 net/core/sock.c:1471
>  [  378.305168] [] sk_common_release+0x28c/0x3e0 
> ./include/net/sock.h:1589
>  [  378.305168] [] udp_lib_close+0x15/0x20 
> ./include/net/udp.h:203
>  [  378.305168] [] inet_release+0xed/0x1c0 
> net/ipv4/af_inet.c:415
>  [  378.305168] [] inet6_release+0x50/0x70 
> net/ipv6/af_inet6.c:422
>  [  378.305168] [] sock_release+0x8d/0x1d0 net/socket.c:570
>  [  378.305168] [] sock_close+0x16/0x20 net/socket.c:1017
>  [  378.305168] [] __fput+0x28c/0x780 fs/file_table.c:208
>  [  378.305168] [] fput+0x15/0x20 fs/file_table.c:244
>  [  378.305168] [] task_work_run+0xf9/0x170
>  [  378.305168] [] do_exit+0x85e/0x2a00
>  [  378.305168] [] do_group_exit+0x108/0x330
>  [  378.376437] [] get_signal+0x617/0x17a0 
> kernel/signal.c:2307
>  [  378.376437] [] do_signal+0x7f/0x18f0
>  [  378.376437] [] exit_to_usermode_loop+0xbf/0x150 
> arch/x86/entry/common.c:156
>  [  378.376437] [< inline >] prepare_exit_to_usermode 
> arch/x86/entry/common.c:190
>  [  378.376437] [] syscall_return_slowpath+0x1a0/0x1e0 
> arch/x86/entry/common.c:259
>  [  378.376437] [] entry_SYSCALL_64_fastpath+0xc4/0xc6
> Memory state around the buggy address:
>  88000804ca00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  88000804ca80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>88000804cb00: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>