Hello,
The following program triggers use-after-free in sctp_do_sm:
// autogenerated by syzkaller (
http://github.com/google/syzkaller)
#include <syscall.h>
#include <string.h>
#include <stdint.h>
int main()
{
long r0 = syscall(SYS_socket, 0xaul, 0x80805ul, 0x0ul, 0, 0, 0);
long r1 = syscall(SYS_mmap, 0x20000000ul, 0x10000ul, 0x3ul,
0x32ul, 0xfffffffffffffffful, 0x0ul);
memcpy((void*)0x20002fe4,
"\x0a\x00\x33\xe7\xeb\x9d\xcf\x61\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x01\xc5\xc8\x88\x64",
28);
long r3 = syscall(SYS_bind, r0, 0x20002fe4ul, 0x1cul, 0, 0, 0);
memcpy((void*)0x20000faa,
"\x9b\x01\x7d\xcd\xb8\x6a\xc7\x3d\x09\x3a\x07\x00\xa7\xc4\xe9\xee\x0a\xd6\xec\xde\x26\x75\x5f\x22\xae\x4e\x33\x00\xb0\x76\x10\x70\xd6\xca\x19\xbc\x15\x83\xcf\x2e\xbc\x99\x0c\x5e\x83\x89\xc1\x44\x9c\x6e\x74\xd8\x5d\x5d\xd0\xf0\xdf\x47\xc0\x00\x71\x0b\x55\x4c\xab\xf0\xd8\x90\xd5\x92\x8c\x6e\x33\x22\x15\x5b\x19\xfb\xed\xdd\xa6\xac\xcb\x60\xcf\xe2\xde\xed\xdb\x95\x5c\xaa\x20\xa3",
94);
memcpy((void*)0x2000033a,
"\x02\x00\x33\xe2\x7f\x00\x00\x01\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00",
128);
long r6 = syscall(SYS_sendto, r0, 0x20000faaul, 0x5eul,
0x81ul, 0x2000033aul, 0x80ul);
return 0;
}
==================================================================
BUG: KASAN: use-after-free in sctp_do_sm+0x42f6/0x4f60 at addr ffff880036fa80a8
Read of size 4 by task a.out/5664
=============================================================================
BUG kmalloc-4096 (Tainted: G B ): kasan: bad access detected
-----------------------------------------------------------------------------
INFO: Allocated in sctp_association_new+0x6f/0x1ea0 age=8 cpu=1 pid=5664
[< none >] kmem_cache_alloc_trace+0x1cf/0x220 ./mm/slab.c:3707
[< none >] sctp_association_new+0x6f/0x1ea0
[< none >] sctp_sendmsg+0x1954/0x28e0
[< none >] inet_sendmsg+0x316/0x4f0 ./net/ipv4/af_inet.c:802
[< inline >] __sock_sendmsg_nosec ./net/socket.c:641
[< inline >] __sock_sendmsg ./net/socket.c:651
[< none >] sock_sendmsg+0xca/0x110 ./net/socket.c:662
[< none >] SYSC_sendto+0x208/0x350 ./net/socket.c:1841
[< none >] SyS_sendto+0x40/0x50 ./net/socket.c:1862
[< none >] entry_SYSCALL_64_fastpath+0x16/0x7a
INFO: Freed in sctp_association_put+0x150/0x250 age=14 cpu=1 pid=5664
[< none >] kfree+0x199/0x1b0 ./mm/slab.c:1211
[< none >] sctp_association_put+0x150/0x250
[< none >] sctp_association_free+0x498/0x630
[< none >] sctp_do_sm+0xd8b/0x4f60
[< none >] sctp_primitive_SHUTDOWN+0xa9/0xd0
[< none >] sctp_close+0x616/0x790
[< none >] inet_release+0xed/0x1c0 ./net/ipv4/af_inet.c:471
[< none >] inet6_release+0x50/0x70 ./net/ipv6/af_inet6.c:416
[< inline >] constant_test_bit ././arch/x86/include/asm/bitops.h:321
[< none >] sock_release+0x8d/0x200 ./net/socket.c:601
[< none >] sock_close+0x16/0x20 ./net/socket.c:1188
[< none >] __fput+0x21d/0x6e0 ./fs/file_table.c:265
[< none >] ____fput+0x15/0x20 ./fs/file_table.c:84
[< none >] task_work_run+0x163/0x1f0 ./include/trace/events/rcu.h:20
[< inline >] __list_add ./include/linux/list.h:42
[< inline >] list_add_tail ./include/linux/list.h:76
[< inline >] list_move_tail ./include/linux/list.h:168
[< inline >] reparent_leader ./kernel/exit.c:618
[< inline >] forget_original_parent ./kernel/exit.c:669
[< inline >] exit_notify ./kernel/exit.c:697
[< none >] do_exit+0x809/0x2b90 ./kernel/exit.c:878
[< none >] do_group_exit+0x108/0x320 ./kernel/exit.c:985
INFO: Slab 0xffffea0000dbea00 objects=7 used=1 fp=0xffff880036fa8000
flags=0x100000000004080
INFO: Object 0xffff880036fa8000 @offset=0 fp=0xffff880036fad668
CPU: 1 PID: 5664 Comm: a.out Tainted: G B 4.4.0-rc1+ #81
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
00000000ffffffff ffff880061d6f700 ffffffff825d3336 ffff88003e806d00
ffff880036fa8000 ffff880036fa8000 ffff880061d6f730 ffffffff81618784
ffff88003e806d00 ffffea0000dbea00 ffff880036fa8000 0000000000000000
Call Trace:
[<ffffffff8162131e>] __asan_report_load4_noabort+0x3e/0x40
[<ffffffff8475ac76>] sctp_do_sm+0x42f6/0x4f60
[<ffffffff847b50e9>] sctp_primitive_SHUTDOWN+0xa9/0xd0
[<ffffffff847a1426>] sctp_close+0x616/0x790
[<ffffffff8409bb0d>] inet_release+0xed/0x1c0 ./net/ipv4/af_inet.c:471
[<ffffffff84192cc0>] inet6_release+0x50/0x70 ./net/ipv6/af_inet6.c:416
[< inline >] constant_test_bit ././arch/x86/include/asm/bitops.h:321
[<ffffffff83dc78cd>] sock_release+0x8d/0x200 ./net/socket.c:601
[<ffffffff83dc7a56>] sock_close+0x16/0x20 ./net/socket.c:1188
[<ffffffff81662f5d>] __fput+0x21d/0x6e0 ./fs/file_table.c:265
[<ffffffff816634a5>] ____fput+0x15/0x20 ./fs/file_table.c:84
[<ffffffff812a33d3>] task_work_run+0x163/0x1f0 ./include/trace/events/rcu.h:20
[< inline >] __list_add ./include/linux/list.h:42
[< inline >] list_add_tail ./include/linux/list.h:76
[< inline >] list_move_tail ./include/linux/list.h:168
[< inline >] reparent_leader ./kernel/exit.c:618
[< inline >] forget_original_parent ./kernel/exit.c:669
[< inline >] exit_notify ./kernel/exit.c:697
[<ffffffff812505d9>] do_exit+0x809/0x2b90 ./kernel/exit.c:878
[<ffffffff81252ad8>] do_group_exit+0x108/0x320 ./kernel/exit.c:985
[<ffffffff81252d0d>] SyS_exit_group+0x1d/0x20 ./kernel/exit.c:1002
[<ffffffff84bf0c36>] entry_SYSCALL_64_fastpath+0x16/0x7a
==================================================================
I am on commit 90b55590c43258a157a2a143748455dcc50fbb53 of net-next (Nov 22).
Thanks