Subject: Re: memory leak in do_ipv6_setsockopt

From: Daniel Borkmann <[email-masked]>
Date: Tue, 01 Dec 2015 15:07:58 +0100

On 12/01/2015 02:36 PM, Eric Dumazet wrote:
> On Tue, 2015-12-01 at 13:27 +0100, Dmitry Vyukov wrote:
>> Hello,
>>
>> The following program causes a memory leak :
>>
>> // autogenerated by syzkaller (http://github.com/google/syzkaller)
>> #include <syscall.h>
>> #include <sys/types.h>
>> #include <sys/socket.h>
>> #include <string.h>
>> #include <stdint.h>
>> #include <linux/in.h>
>> #include <linux/socket.h>
>>
>> int main()
>> {
>>          long r1 = syscall(SYS_socket, PF_INET6,
>> SOCK_STREAM|SOCK_CLOEXEC|SOCK_NONBLOCK, IPPROTO_SCTP);
>>          const char *opt = "\x15\x53\x5e\x2d\x97\xab\xe1";
>>          long r3 = syscall(SYS_setsockopt, r1, 0x29ul, 0x6ul, opt, 0x7ul);
>>          return 0;
>> }
>>
>>
>> unreferenced object 0xffff880039a55260 (size 64):
>>    comm "executor", pid 11746, jiffies 4298984475 (age 16.078s)
>>    hex dump (first 32 bytes):
>>      2f 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  /...............
>>      00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
>>    backtrace:
>>      [<     inline     >] kmalloc include/linux/slab.h:463
>>      [<ffffffff848a2f5f>] sock_kmalloc+0x7f/0xc0 net/core/sock.c:1774
>>      [<ffffffff84e5bea0>] do_ipv6_setsockopt.isra.7+0x15d0/0x2830
>> net/ipv6/ipv6_sockglue.c:483
>>      [<ffffffff84e5d19b>] ipv6_setsockopt+0x9b/0x140 net/ipv6/ipv6_sockglue.c:885
>>      [<ffffffff8544616c>] sctp_setsockopt+0x15c/0x36c0 net/sctp/socket.c:3702
>>      [<ffffffff848a2035>] sock_common_setsockopt+0x95/0xd0 net/core/sock.c:2645
>>      [<     inline     >] SYSC_setsockopt net/socket.c:1757
>>      [<ffffffff8489f1d8>] SyS_setsockopt+0x158/0x240 net/socket.c:1736
>>
>>
>> I confirmed that running this program in a loop steadily increases
>> number of objects in kmalloc-64 slab. The leak does not happen with
>> IPPROTO_TCP, so probably it is sctp-related.
>
> Thanks for the report.
>
> Probably fixed by :
>
> diff --git a/net/sctp/socket.c b/net/sctp/socket.c
> index 897c01c029ca..8079ecd8465d 100644
> --- a/net/sctp/socket.c
> +++ b/net/sctp/socket.c
> @@ -7375,6 +7375,12 @@ struct proto sctp_prot = {
>
>   #if IS_ENABLED(CONFIG_IPV6)
>
> +static void sctp_v6_destroy_sock(struct sock *sk)
> +{
> +	sctp_destroy_sock(sk);
> +	inet6_destroy_sock(sk);
> +}

Yeah, we miss inet6_destroy_sock() in SCTP. :-(

Looks good to me.

>   struct proto sctpv6_prot = {
>   	.name		= "SCTPv6",
>   	.owner		= THIS_MODULE,
> @@ -7384,7 +7390,7 @@ struct proto sctpv6_prot = {
>   	.accept		= sctp_accept,
>   	.ioctl		= sctp_ioctl,
>   	.init		= sctp_init_sock,
> -	.destroy	= sctp_destroy_sock,
> +	.destroy	= sctp_v6_destroy_sock,
>   	.shutdown	= sctp_shutdown,
>   	.setsockopt	= sctp_setsockopt,
>   	.getsockopt	= sctp_getsockopt,
>
>
> --
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