use-after-free in ip6_xmit --- syscall(SYS_connect, arg, &sa, sizeof(sa), 0, 0, 0);

原创

ztguang_张同光 2022-05-24 13:27:27 博主文章分类：086_网络协议—TCP/IP ©著作权

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https://groups.google.com/g/syzkaller/c/YpU1_PMV_gU/m/FmLVGHqTCAAJ

Hello,

The following program triggers use-after-free in ip6_xmit:

// autogenerated by syzkaller (http://github.com/google/syzkaller)

#include <syscall.h>

#include <string.h>

#include <stdint.h>

#include <pthread.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <linux/socket.h>

#include <linux/in.h>

#include <linux/in6.h>

#include <unistd.h>

#include <stdlib.h>

void *thr0(void *arg)

{

*(uint32_t*)0x20000000 = 0x5;

long r5 = syscall(SYS_setsockopt, arg, 0x29ul, 0x6ul,

0x20000000ul, 0x4ul, 0);

return 0;

}

void *thr1(void *arg)

{

struct sockaddr_in6 sa = {};

sa.sin6_family = AF_INET6;

sa.sin6_port = getpid();

sa.sin6_addr.s6_addr[15] = 1;

syscall(SYS_bind, arg, &sa, sizeof(sa), 0, 0, 0);

return 0;

}

void *thr2(void *arg)

{

struct sockaddr_in6 sa = {};

sa.sin6_family = AF_INET6;

sa.sin6_port = getpid();

sa.sin6_addr.s6_addr[15] = 1;

syscall(SYS_connect, arg, &sa, sizeof(sa), 0, 0, 0);

return 0;

}

void *thr3(void *arg)

{

syscall(SYS_listen, arg, 0x3ul, 0, 0, 0, 0);

return 0;

}

void *thr4(void *arg)

{

syscall(SYS_accept4, arg, 0, 0, 0x800ul, 0, 0);

return 0;

}

int main()

{

srand(getpid());

syscall(SYS_mmap, 0x20000000ul, 0x10000ul, 0x2ul, 0x32ul,

0xfffffffffffffffful, 0x0ul);

int fd[2];

fd[0] = syscall(SYS_socket, PF_INET6, SOCK_STREAM, IPPROTO_TCP);

fd[1] = syscall(SYS_socket, PF_INET6, SOCK_STREAM, IPPROTO_TCP);

pthread_t th;

pthread_create(&th, 0, thr0, (void*)(long)fd[0]);

pthread_create(&th, 0, thr1, (void*)(long)fd[0]);

pthread_create(&th, 0, thr2, (void*)(long)fd[0]);

pthread_create(&th, 0, thr3, (void*)(long)fd[0]);

pthread_create(&th, 0, thr4, (void*)(long)fd[0]);

pthread_create(&th, 0, thr0, (void*)(long)fd[0]);

pthread_create(&th, 0, thr1, (void*)(long)fd[0]);

pthread_create(&th, 0, thr2, (void*)(long)fd[0]);

pthread_create(&th, 0, thr3, (void*)(long)fd[0]);

pthread_create(&th, 0, thr4, (void*)(long)fd[0]);

pthread_create(&th, 0, thr0, (void*)(long)fd[1]);

pthread_create(&th, 0, thr1, (void*)(long)fd[1]);

pthread_create(&th, 0, thr2, (void*)(long)fd[1]);

pthread_create(&th, 0, thr3, (void*)(long)fd[1]);

pthread_create(&th, 0, thr4, (void*)(long)fd[1]);

pthread_create(&th, 0, thr0, (void*)(long)fd[1]);

pthread_create(&th, 0, thr1, (void*)(long)fd[1]);

pthread_create(&th, 0, thr2, (void*)(long)fd[1]);

pthread_create(&th, 0, thr3, (void*)(long)fd[1]);

pthread_create(&th, 0, thr4, (void*)(long)fd[1]);

usleep(20000);

return 0;

}

==================================================================

BUG: KASAN: use-after-free in ip6_xmit+0x15e3/0x1f50 at addr ffff88003991c786

Read of size 2 by task a.out/6864

=============================================================================

BUG kmalloc-64 (Not tainted): kasan: bad access detected

-----------------------------------------------------------------------------

Disabling lock debugging due to kernel taint

INFO: Allocated in sock_kmalloc+0x93/0x100 age=40 cpu=1 pid=6850

[< none >] ___slab_alloc+0x648/0x8c0 mm/slub.c:2438

[< none >] __slab_alloc+0x4c/0x90 mm/slub.c:2467

[< inline >] slab_alloc_node mm/slub.c:2530

[< inline >] slab_alloc mm/slub.c:2572

[< none >] __kmalloc+0x2d9/0x480 mm/slub.c:3532

[< inline >] kmalloc include/linux/slab.h:463

[< none >] sock_kmalloc+0x93/0x100 net/core/sock.c:1772

[< none >] do_ipv6_setsockopt.isra.5+0xf4d/0x2d30

net/ipv6/ipv6_sockglue.c:483

[< none >] ipv6_setsockopt+0x4f/0x150 net/ipv6/ipv6_sockglue.c:885

[< none >] sctp_setsockopt+0x194/0x4020 net/sctp/socket.c:3702

[< none >] sock_common_setsockopt+0xb4/0x140 net/core/sock.c:2643

[< inline >] SYSC_setsockopt net/socket.c:1757

[< none >] SyS_setsockopt+0x161/0x290 net/socket.c:1736

[< none >] entry_SYSCALL_64_fastpath+0x16/0x7a

arch/x86/entry/entry_64.S:185

INFO: Freed in sock_kfree_s+0x29/0x90 age=34 cpu=0 pid=6855

[< none >] __slab_free+0x21e/0x3e0 mm/slub.c:2648

[< inline >] slab_free mm/slub.c:2803

[< none >] kfree+0x26f/0x3e0 mm/slub.c:3632

[< inline >] __sock_kfree_s net/core/sock.c:1793

[< none >] sock_kfree_s+0x29/0x90 net/core/sock.c:1799

[< none >] do_ipv6_setsockopt.isra.5+0x100f/0x2d30

net/ipv6/ipv6_sockglue.c:506

[< none >] ipv6_setsockopt+0x4f/0x150 net/ipv6/ipv6_sockglue.c:885

[< none >] sctp_setsockopt+0x194/0x4020 net/sctp/socket.c:3702

[< none >] sock_common_setsockopt+0xb4/0x140 net/core/sock.c:2643

[< inline >] SYSC_setsockopt net/socket.c:1757

[< none >] SyS_setsockopt+0x161/0x290 net/socket.c:1736

[< none >] entry_SYSCALL_64_fastpath+0x16/0x7a

arch/x86/entry/entry_64.S:185

INFO: Slab 0xffffea0000e64700 objects=21 used=19 fp=0xffff88003991cc00

flags=0x1fffc0000004080

INFO: Object 0xffff88003991c780 @offset=1920 fp=0x (null)

CPU: 2 PID: 6864 Comm: a.out Tainted: G B 4.4.0-rc3+ #150

Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011

0000000000000002 ffff88005f3f6e18 ffffffff82c6f2a8 0000000041b58ab3

ffffffff8788bf8d ffffffff82c6f1f6 ffff880062045a00 ffffffff878ac723

ffff88003e807700 0000000000000008 ffff88003991c780 ffff88005f3f6e18

Call Trace:

[< inline >] __dump_stack lib/dump_stack.c:15

[<ffffffff82c6f2a8>] dump_stack+0xb2/0xfa lib/dump_stack.c:50

[<ffffffff81788e3c>] print_trailer+0x12c/0x210 mm/slub.c:652

[<ffffffff81793c5f>] object_err+0x2f/0x40 mm/slub.c:659

[< inline >] print_address_description mm/kasan/report.c:138

[<ffffffff817979c9>] kasan_report_error+0x5d9/0x860 mm/kasan/report.c:251

[< inline >] kasan_report mm/kasan/report.c:274

[<ffffffff81797d14>] __asan_report_load2_noabort+0x54/0x70

mm/kasan/report.c:293

[<ffffffff85bc06e3>] ip6_xmit+0x15e3/0x1f50 net/ipv6/ip6_output.c:176

[<ffffffff8635a0b9>] sctp_v6_xmit+0x319/0x530 net/sctp/ipv6.c:223

[<ffffffff8634595d>] sctp_packet_transmit+0x113d/0x2680 net/sctp/output.c:595

[<ffffffff8630e897>] sctp_outq_flush+0x717/0x2840 net/sctp/outqueue.c:1090

[<ffffffff86315d67>] sctp_outq_uncork+0x57/0x80 net/sctp/outqueue.c:692

[< inline >] sctp_cmd_interpreter net/sctp/sm_sideeffect.c:1750

[< inline >] sctp_side_effects net/sctp/sm_sideeffect.c:1153

[<ffffffff862d9e83>] sctp_do_sm+0x38a3/0x5be0 net/sctp/sm_sideeffect.c:1125

[<ffffffff863423c9>] sctp_primitive_SHUTDOWN+0xa9/0xd0 net/sctp/primitive.c:104

[<ffffffff8632e94d>] sctp_close+0x6fd/0x9b0 net/sctp/socket.c:1519

[<ffffffff85a4b2a1>] inet_release+0x111/0x270 net/ipv4/af_inet.c:413

[<ffffffff85bac8c5>] inet6_release+0x55/0x90 net/ipv6/af_inet6.c:406

[<ffffffff85501586>] sock_release+0x96/0x260 net/socket.c:571

[<ffffffff85501766>] sock_close+0x16/0x20 net/socket.c:1022

[<ffffffff817f0014>] __fput+0x244/0x860 fs/file_table.c:208

[<ffffffff817f06c5>] ____fput+0x15/0x20 fs/file_table.c:244

[<ffffffff8133a5e0>] task_work_run+0x130/0x240 kernel/task_work.c:115

[< inline >] exit_task_work include/linux/task_work.h:21

[<ffffffff812d4a05>] do_exit+0x885/0x3050 kernel/exit.c:750

[<ffffffff812d732c>] do_group_exit+0xec/0x390 kernel/exit.c:880

[<ffffffff81302177>] get_signal+0x677/0x1bf0 kernel/signal.c:2307

[<ffffffff8118645e>] do_signal+0x7e/0x2170 arch/x86/kernel/signal.c:709

[<ffffffff81003a1e>] exit_to_usermode_loop+0xfe/0x1e0

arch/x86/entry/common.c:247

[< inline >] prepare_exit_to_usermode arch/x86/entry/common.c:282

[<ffffffff8100733b>] syscall_return_slowpath+0x16b/0x240

arch/x86/entry/common.c:344

[<ffffffff868dafe2>] int_ret_from_sys_call+0x25/0x9f

arch/x86/entry/entry_64.S:281

==================================================================

On commit 31ade3b83e1821da5fbb2f11b5b3d4ab2ec39db8.

The allocation/free stacks look similar to the ones I reported in

"memory leak in do_ipv6_setsockopt". However, the fix for that leak

suggests that it could lead only to leaks, not to use-after-frees.

Eric Dumazet

未读，

2015年12月7日 22:36:23

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

收件人 Dmitry Vyukov、David S. Miller、Alexey Kuznetsov、James Morris、Hideaki YOSHIFUJI、Patrick McHardy、netdev、LKML、Vlad Yasevich、Neil Horman、linux...@vger.kernel.org、syzkaller、Kostya Serebryany、Alexander Potapenko、Eric Dumazet、Sasha Levin



> --

I thought I already fixed these, based on your report ?

commit 6bd4f355df2eae80b8a5c7b097371cd1e05f20d5

Author: Eric Dumazet <edum...@google.com>

Date: Wed Dec 2 21:53:57 2015 -0800

ipv6: kill sk_dst_lock

While testing the np->opt RCU conversion, I found that UDP/IPv6 was

using a mixture of xchg() and sk_dst_lock to protect concurrent changes

to sk->sk_dst_cache, leading to possible corruptions and crashes.

ip6_sk_dst_lookup_flow() uses sk_dst_check() anyway, so the simplest

way to fix the mess is to remove sk_dst_lock completely, as we did for

IPv4.

__ip6_dst_store() and ip6_dst_store() share same implementation.

sk_setup_caps() being called with socket lock being held or not,

we have to use sk_dst_set() instead of __sk_dst_set()

Note that I had to move the "np->dst_cookie = rt6_get_cookie(rt);"

in ip6_dst_store() before the sk_setup_caps(sk, dst) call.

This is because ip6_dst_store() can be called from process context,

without any lock held.

As soon as the dst is installed in sk->sk_dst_cache, dst can be freed

from another cpu doing a concurrent ip6_dst_store()

Doing the dst dereference before doing the install is needed to make

sure no use after free would trigger.

Signed-off-by: Eric Dumazet <edum...@google.com>

Reported-by: Dmitry Vyukov <dvy...@google.com>

Signed-off-by: David S. Miller <da...@davemloft.net>

commit 45f6fad84cc305103b28d73482b344d7f5b76f39

Author: Eric Dumazet <edum...@google.com>

Date: Sun Nov 29 19:37:57 2015 -0800

ipv6: add complete rcu protection around np->opt

This patch addresses multiple problems :

UDP/RAW sendmsg() need to get a stable struct ipv6_txoptions

while socket is not locked : Other threads can change np->opt

concurrently. Dmitry posted a syzkaller

(http://github.com/google/syzkaller) program desmonstrating

use-after-free.

Starting with TCP/DCCP lockless listeners, tcp_v6_syn_recv_sock()

and dccp_v6_request_recv_sock() also need to use RCU protection

to dereference np->opt once (before calling ipv6_dup_options())

This patch adds full RCU protection to np->opt

Reported-by: Dmitry Vyukov <dvy...@google.com>

Signed-off-by: Eric Dumazet <edum...@google.com>

Acked-by: Hannes Frederic Sowa <han...@stressinduktion.org>

Signed-off-by: David S. Miller <da...@davemloft.net>

commit 602dd62dfbda3e63a2d6a3cbde953ebe82bf5087

Author: Eric Dumazet <edum...@google.com>

Date: Tue Dec 1 07:20:07 2015 -0800

ipv6: sctp: implement sctp_v6_destroy_sock()

Dmitry Vyukov reported a memory leak using IPV6 SCTP sockets.

We need to call inet6_destroy_sock() to properly release

inet6 specific fields.

Reported-by: Dmitry Vyukov <dvy...@google.com>

Signed-off-by: Eric Dumazet <edum...@google.com>

Acked-by: Daniel Borkmann <dan...@iogearbox.net>

Signed-off-by: David S. Miller <da...@davemloft.net>

commit c836a8ba93869d6a0290a6ae0047fbef09066871

Author: Eric Dumazet <edum...@google.com>

Date: Wed Dec 2 21:48:14 2015 -0800

ipv6: sctp: add rcu protection around np->opt

This patch completes the work I did in commit 45f6fad84cc3

("ipv6: add complete rcu protection around np->opt"), as I missed

sctp part.

This simply makes sure np->opt is used with proper RCU locking

and accessors.

Signed-off-by: Eric Dumazet <edum...@google.com>

Signed-off-by: David S. Miller <da...@davemloft.net>

Can you double check based on linux-4.4-rc4 instead of linux-4.4-rc3 ?

Thanks

Eric Dumazet

未读，

2015年12月7日 22:39:06

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



On Mon, 2015-12-07 at 06:36 -0800, Eric Dumazet wrote:

> Thanks

Also note that Dave Jones reported a SCTP problem fixed by :

https://patchwork.ozlabs.org/patch/553068/

Dmitry Vyukov

未读，

2015年12月7日 22:45:09

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



收件人 Eric Dumazet、David S. Miller、Alexey Kuznetsov、James Morris、Hideaki YOSHIFUJI、Patrick McHardy、netdev、LKML、Vlad Yasevich、Neil Horman、linux...@vger.kernel.org、syzkaller、Kostya Serebryany、Alexander Potapenko、Eric Dumazet、Sasha Levin

Yes, seems to be fixed on master of

git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git. Just

can't pull in all fixes from all trees. Sorry.

When will it be merged into Linus tree?



Eric Dumazet

未读，

2015年12月7日 23:22:49







收件人 Dmitry Vyukov、Eric Dumazet、David S. Miller、Alexey Kuznetsov、James Morris、Hideaki YOSHIFUJI、Patrick McHardy、netdev、LKML、Vlad Yasevich、Neil Horman、linux...@vger.kernel.org、syzkaller、Kostya Serebryany、Alexander Potapenko、Sasha Levin

On Mon, Dec 7, 2015 at 6:44 AM, Dmitry Vyukov <dvy...@google.com> wrote:

> Yes, seems to be fixed on master of

> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net.git. Just

> can't pull in all fixes from all trees. Sorry.

> When will it be merged into Linus tree?

As I said, they are already in Linus tree, part of linux-4.4-rc4,

released yesterday.

I would like to remind you lkml and netdev have thousands of subscribers,

so please do not flood them with duplicates, especially considering

you were CC on all

the patches I cooked to address your original report.

So you knew patches were on their way.