On Fri, Oct 27, 2017 at 11:18 PM, Cong Wang <[email protected]> wrote:
> On Thu, Oct 26, 2017 at 11:00 PM, Dmitry Vyukov <[email protected]> wrote:
>> On Thu, Oct 26, 2017 at 7:58 PM, Tejun Heo <[email protected]> wrote:
>>> Hello,
>>>
>>> On Thu, Oct 26, 2017 at 09:35:44AM -0700, syzbot wrote:
>>>> BUG: KASAN: use-after-free in __read_once_size
>>>> include/linux/compiler.h:276 [inline]
>>>> BUG: KASAN: use-after-free in atomic64_read
>>>> arch/x86/include/asm/atomic64_64.h:21 [inline]
>>>> BUG: KASAN: use-after-free in atomic_long_read
>>>> include/asm-generic/atomic-long.h:44 [inline]
>>>> BUG: KASAN: use-after-free in get_work_pool+0x1c2/0x1e0
>>>> kernel/workqueue.c:709
>>>> Read of size 8 at addr ffff8801cc58c378 by task syz-executor5/21326
>>>>
>>>> CPU: 1 PID: 21326 Comm: syz-executor5 Not tainted 4.13.0+ #43
>>>> Hardware name: Google Google Compute Engine/Google Compute Engine,
>>>> BIOS Google 01/01/2011
>>>> Call Trace:
>>>> __dump_stack lib/dump_stack.c:16 [inline]
>>>> dump_stack+0x194/0x257 lib/dump_stack.c:52
>>>> print_address_description+0x73/0x250 mm/kasan/report.c:252
>>>> kasan_report_error mm/kasan/report.c:351 [inline]
>>>> kasan_report+0x24e/0x340 mm/kasan/report.c:409
>>>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
>>>> __read_once_size include/linux/compiler.h:276 [inline]
>>>> atomic64_read arch/x86/include/asm/atomic64_64.h:21 [inline]
>>>> atomic_long_read include/asm-generic/atomic-long.h:44 [inline]
>>>> get_work_pool+0x1c2/0x1e0 kernel/workqueue.c:709
>>>> __queue_work+0x235/0x1150 kernel/workqueue.c:1401
>>>> queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1486
>>>> queue_work include/linux/workqueue.h:489 [inline]
>>>> strp_check_rcv+0x25/0x30 net/strparser/strparser.c:553
>>>> kcm_attach net/kcm/kcmsock.c:1439 [inline]
>>>> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>>>> kcm_ioctl+0x826/0x1610 net/kcm/kcmsock.c:1695
>>>> sock_do_ioctl+0x65/0xb0 net/socket.c:961
>>>> sock_ioctl+0x2c2/0x440 net/socket.c:1058
>>>> vfs_ioctl fs/ioctl.c:45 [inline]
>>>> do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
>>>> SYSC_ioctl fs/ioctl.c:700 [inline]
>>>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>>>> entry_SYSCALL_64_fastpath+0x1f/0xbe
>>>
>>> Looks like kcm is trying to reuse a work item whose last workqueue has
>>> been destroyed without re-initing it. A work item needs to be
>>> reinit'd.
>>
>> +kcm maintainers
>
> Can you try the fix below? There is no C reproducer so I can't verify it.
Hi Cong,
syzbot can now test proposed patches, see
https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
for details. Please give it a try.
> diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
> index af4e76ac88ff..7816f44c576a 100644
> --- a/net/kcm/kcmsock.c
> +++ b/net/kcm/kcmsock.c
> @@ -1433,11 +1433,12 @@ static int kcm_attach(struct socket *sock,
> struct socket *csock,
> KCM_STATS_INCR(mux->stats.psock_attach);
> mux->psocks_cnt++;
> psock_now_avail(psock);
> - spin_unlock_bh(&mux->lock);
>
> /* Schedule RX work in case there are already bytes queued */
> strp_check_rcv(&psock->strp);
>
> + spin_unlock_bh(&mux->lock);
> +
> return 0;
> }
On Wed, Dec 6, 2017 at 1:50 PM, Dmitry Vyukov <[email protected]> wrote:
> On Fri, Oct 27, 2017 at 11:18 PM, Cong Wang <[email protected]> wrote:
>> On Thu, Oct 26, 2017 at 11:00 PM, Dmitry Vyukov <[email protected]> wrote:
>>> On Thu, Oct 26, 2017 at 7:58 PM, Tejun Heo <[email protected]> wrote:
>>>> Hello,
>>>>
>>>> On Thu, Oct 26, 2017 at 09:35:44AM -0700, syzbot wrote:
>>>>> BUG: KASAN: use-after-free in __read_once_size
>>>>> include/linux/compiler.h:276 [inline]
>>>>> BUG: KASAN: use-after-free in atomic64_read
>>>>> arch/x86/include/asm/atomic64_64.h:21 [inline]
>>>>> BUG: KASAN: use-after-free in atomic_long_read
>>>>> include/asm-generic/atomic-long.h:44 [inline]
>>>>> BUG: KASAN: use-after-free in get_work_pool+0x1c2/0x1e0
>>>>> kernel/workqueue.c:709
>>>>> Read of size 8 at addr ffff8801cc58c378 by task syz-executor5/21326
>>>>>
>>>>> CPU: 1 PID: 21326 Comm: syz-executor5 Not tainted 4.13.0+ #43
>>>>> Hardware name: Google Google Compute Engine/Google Compute Engine,
>>>>> BIOS Google 01/01/2011
>>>>> Call Trace:
>>>>> __dump_stack lib/dump_stack.c:16 [inline]
>>>>> dump_stack+0x194/0x257 lib/dump_stack.c:52
>>>>> print_address_description+0x73/0x250 mm/kasan/report.c:252
>>>>> kasan_report_error mm/kasan/report.c:351 [inline]
>>>>> kasan_report+0x24e/0x340 mm/kasan/report.c:409
>>>>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
>>>>> __read_once_size include/linux/compiler.h:276 [inline]
>>>>> atomic64_read arch/x86/include/asm/atomic64_64.h:21 [inline]
>>>>> atomic_long_read include/asm-generic/atomic-long.h:44 [inline]
>>>>> get_work_pool+0x1c2/0x1e0 kernel/workqueue.c:709
>>>>> __queue_work+0x235/0x1150 kernel/workqueue.c:1401
>>>>> queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1486
>>>>> queue_work include/linux/workqueue.h:489 [inline]
>>>>> strp_check_rcv+0x25/0x30 net/strparser/strparser.c:553
>>>>> kcm_attach net/kcm/kcmsock.c:1439 [inline]
>>>>> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>>>>> kcm_ioctl+0x826/0x1610 net/kcm/kcmsock.c:1695
>>>>> sock_do_ioctl+0x65/0xb0 net/socket.c:961
>>>>> sock_ioctl+0x2c2/0x440 net/socket.c:1058
>>>>> vfs_ioctl fs/ioctl.c:45 [inline]
>>>>> do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
>>>>> SYSC_ioctl fs/ioctl.c:700 [inline]
>>>>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>>>>> entry_SYSCALL_64_fastpath+0x1f/0xbe
>>>>
>>>> Looks like kcm is trying to reuse a work item whose last workqueue has
>>>> been destroyed without re-initing it. A work item needs to be
>>>> reinit'd.
>>>
>>> +kcm maintainers
>>
>> Can you try the fix below? There is no C reproducer so I can't verify it.
>
>
> Hi Cong,
>
> syzbot can now test proposed patches, see
> https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
> for details. Please give it a try.
>
>> diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
>> index af4e76ac88ff..7816f44c576a 100644
>> --- a/net/kcm/kcmsock.c
>> +++ b/net/kcm/kcmsock.c
>> @@ -1433,11 +1433,12 @@ static int kcm_attach(struct socket *sock,
>> struct socket *csock,
>> KCM_STATS_INCR(mux->stats.psock_attach);
>> mux->psocks_cnt++;
>> psock_now_avail(psock);
>> - spin_unlock_bh(&mux->lock);
>>
>> /* Schedule RX work in case there are already bytes queued */
>> strp_check_rcv(&psock->strp);
>>
>> + spin_unlock_bh(&mux->lock);
>> +
>> return 0;
>> }
Hi Cong,
Was this ever merged? Is it still necessary?
On Wed, Feb 14, 2018 at 02:45:05PM +0100, 'Dmitry Vyukov' via syzkaller-bugs wrote:
> On Wed, Dec 6, 2017 at 1:50 PM, Dmitry Vyukov <[email protected]> wrote:
> > On Fri, Oct 27, 2017 at 11:18 PM, Cong Wang <[email protected]> wrote:
> >> On Thu, Oct 26, 2017 at 11:00 PM, Dmitry Vyukov <[email protected]> wrote:
> >>> On Thu, Oct 26, 2017 at 7:58 PM, Tejun Heo <[email protected]> wrote:
> >>>> Hello,
> >>>>
> >>>> On Thu, Oct 26, 2017 at 09:35:44AM -0700, syzbot wrote:
> >>>>> BUG: KASAN: use-after-free in __read_once_size
> >>>>> include/linux/compiler.h:276 [inline]
> >>>>> BUG: KASAN: use-after-free in atomic64_read
> >>>>> arch/x86/include/asm/atomic64_64.h:21 [inline]
> >>>>> BUG: KASAN: use-after-free in atomic_long_read
> >>>>> include/asm-generic/atomic-long.h:44 [inline]
> >>>>> BUG: KASAN: use-after-free in get_work_pool+0x1c2/0x1e0
> >>>>> kernel/workqueue.c:709
> >>>>> Read of size 8 at addr ffff8801cc58c378 by task syz-executor5/21326
> >>>>>
> >>>>> CPU: 1 PID: 21326 Comm: syz-executor5 Not tainted 4.13.0+ #43
> >>>>> Hardware name: Google Google Compute Engine/Google Compute Engine,
> >>>>> BIOS Google 01/01/2011
> >>>>> Call Trace:
> >>>>> __dump_stack lib/dump_stack.c:16 [inline]
> >>>>> dump_stack+0x194/0x257 lib/dump_stack.c:52
> >>>>> print_address_description+0x73/0x250 mm/kasan/report.c:252
> >>>>> kasan_report_error mm/kasan/report.c:351 [inline]
> >>>>> kasan_report+0x24e/0x340 mm/kasan/report.c:409
> >>>>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
> >>>>> __read_once_size include/linux/compiler.h:276 [inline]
> >>>>> atomic64_read arch/x86/include/asm/atomic64_64.h:21 [inline]
> >>>>> atomic_long_read include/asm-generic/atomic-long.h:44 [inline]
> >>>>> get_work_pool+0x1c2/0x1e0 kernel/workqueue.c:709
> >>>>> __queue_work+0x235/0x1150 kernel/workqueue.c:1401
> >>>>> queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1486
> >>>>> queue_work include/linux/workqueue.h:489 [inline]
> >>>>> strp_check_rcv+0x25/0x30 net/strparser/strparser.c:553
> >>>>> kcm_attach net/kcm/kcmsock.c:1439 [inline]
> >>>>> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
> >>>>> kcm_ioctl+0x826/0x1610 net/kcm/kcmsock.c:1695
> >>>>> sock_do_ioctl+0x65/0xb0 net/socket.c:961
> >>>>> sock_ioctl+0x2c2/0x440 net/socket.c:1058
> >>>>> vfs_ioctl fs/ioctl.c:45 [inline]
> >>>>> do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
> >>>>> SYSC_ioctl fs/ioctl.c:700 [inline]
> >>>>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
> >>>>> entry_SYSCALL_64_fastpath+0x1f/0xbe
> >>>>
> >>>> Looks like kcm is trying to reuse a work item whose last workqueue has
> >>>> been destroyed without re-initing it. A work item needs to be
> >>>> reinit'd.
> >>>
> >>> +kcm maintainers
> >>
> >> Can you try the fix below? There is no C reproducer so I can't verify it.
> >
> >
> > Hi Cong,
> >
> > syzbot can now test proposed patches, see
> > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
> > for details. Please give it a try.
> >
> >> diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
> >> index af4e76ac88ff..7816f44c576a 100644
> >> --- a/net/kcm/kcmsock.c
> >> +++ b/net/kcm/kcmsock.c
> >> @@ -1433,11 +1433,12 @@ static int kcm_attach(struct socket *sock,
> >> struct socket *csock,
> >> KCM_STATS_INCR(mux->stats.psock_attach);
> >> mux->psocks_cnt++;
> >> psock_now_avail(psock);
> >> - spin_unlock_bh(&mux->lock);
> >>
> >> /* Schedule RX work in case there are already bytes queued */
> >> strp_check_rcv(&psock->strp);
> >>
> >> + spin_unlock_bh(&mux->lock);
> >> +
> >> return 0;
> >> }
>
>
> Hi Cong,
>
> Was this ever merged? Is it still necessary?
>
syzbot is no longer hitting this bug for some reason but it's still there. Tom,
it looks like you wrote the buggy code (it's yet another KCM bug, apparently);
can you please look into it?
I've put together a C reproducer that works on latest linux-next (next-20180309,
commit 61530b14b059d). It works as an unprivileged user provided that KCM is
enabled, and that KASAN is enabled so you see the use-after-free report:
#include <linux/bpf.h>
#include <linux/in.h>
#include <linux/kcm.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/syscall.h>
#include <unistd.h>
int main()
{
union bpf_attr prog = {
.prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
.insn_cnt = 2,
.insns = (__u64)(__u64[]){ 0xb7, 0x95 },
.license = (__u64)"",
};
int tcp_fd, bpf_fd, kcm_fd;
struct sockaddr_in addr = {
.sin_family = AF_INET,
.sin_port = __constant_htons(3270),
.sin_addr = { __constant_htonl(0x7f000001) }
};
tcp_fd = socket(AF_INET, SOCK_STREAM, 0);
bind(tcp_fd, (void *)&addr, sizeof(addr));
listen(tcp_fd, 1);
tcp_fd = socket(AF_INET, SOCK_STREAM, 0);
connect(tcp_fd, (void *)&addr, sizeof(addr));
bpf_fd = syscall(__NR_bpf, BPF_PROG_LOAD, &prog, 48);
kcm_fd = socket(AF_KCM, SOCK_SEQPACKET, 0);
if (fork() == 0) {
struct kcm_attach attach = { tcp_fd, bpf_fd };
for (;;)
ioctl(kcm_fd, SIOCKCMATTACH, &attach);
} else {
struct kcm_unattach unattach = { tcp_fd };
for (;;)
ioctl(kcm_fd, SIOCKCMUNATTACH, &unattach);
}
}
On Sun, Mar 11, 2018 at 2:34 PM, Eric Biggers <[email protected]> wrote:
> On Wed, Feb 14, 2018 at 02:45:05PM +0100, 'Dmitry Vyukov' via syzkaller-bugs wrote:
>> On Wed, Dec 6, 2017 at 1:50 PM, Dmitry Vyukov <[email protected]> wrote:
>> > On Fri, Oct 27, 2017 at 11:18 PM, Cong Wang <[email protected]> wrote:
>> >> On Thu, Oct 26, 2017 at 11:00 PM, Dmitry Vyukov <[email protected]> wrote:
>> >>> On Thu, Oct 26, 2017 at 7:58 PM, Tejun Heo <[email protected]> wrote:
>> >>>> Hello,
>> >>>>
>> >>>> On Thu, Oct 26, 2017 at 09:35:44AM -0700, syzbot wrote:
>> >>>>> BUG: KASAN: use-after-free in __read_once_size
>> >>>>> include/linux/compiler.h:276 [inline]
>> >>>>> BUG: KASAN: use-after-free in atomic64_read
>> >>>>> arch/x86/include/asm/atomic64_64.h:21 [inline]
>> >>>>> BUG: KASAN: use-after-free in atomic_long_read
>> >>>>> include/asm-generic/atomic-long.h:44 [inline]
>> >>>>> BUG: KASAN: use-after-free in get_work_pool+0x1c2/0x1e0
>> >>>>> kernel/workqueue.c:709
>> >>>>> Read of size 8 at addr ffff8801cc58c378 by task syz-executor5/21326
>> >>>>>
>> >>>>> CPU: 1 PID: 21326 Comm: syz-executor5 Not tainted 4.13.0+ #43
>> >>>>> Hardware name: Google Google Compute Engine/Google Compute Engine,
>> >>>>> BIOS Google 01/01/2011
>> >>>>> Call Trace:
>> >>>>> __dump_stack lib/dump_stack.c:16 [inline]
>> >>>>> dump_stack+0x194/0x257 lib/dump_stack.c:52
>> >>>>> print_address_description+0x73/0x250 mm/kasan/report.c:252
>> >>>>> kasan_report_error mm/kasan/report.c:351 [inline]
>> >>>>> kasan_report+0x24e/0x340 mm/kasan/report.c:409
>> >>>>> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
>> >>>>> __read_once_size include/linux/compiler.h:276 [inline]
>> >>>>> atomic64_read arch/x86/include/asm/atomic64_64.h:21 [inline]
>> >>>>> atomic_long_read include/asm-generic/atomic-long.h:44 [inline]
>> >>>>> get_work_pool+0x1c2/0x1e0 kernel/workqueue.c:709
>> >>>>> __queue_work+0x235/0x1150 kernel/workqueue.c:1401
>> >>>>> queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1486
>> >>>>> queue_work include/linux/workqueue.h:489 [inline]
>> >>>>> strp_check_rcv+0x25/0x30 net/strparser/strparser.c:553
>> >>>>> kcm_attach net/kcm/kcmsock.c:1439 [inline]
>> >>>>> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline]
>> >>>>> kcm_ioctl+0x826/0x1610 net/kcm/kcmsock.c:1695
>> >>>>> sock_do_ioctl+0x65/0xb0 net/socket.c:961
>> >>>>> sock_ioctl+0x2c2/0x440 net/socket.c:1058
>> >>>>> vfs_ioctl fs/ioctl.c:45 [inline]
>> >>>>> do_vfs_ioctl+0x1b1/0x1530 fs/ioctl.c:685
>> >>>>> SYSC_ioctl fs/ioctl.c:700 [inline]
>> >>>>> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:691
>> >>>>> entry_SYSCALL_64_fastpath+0x1f/0xbe
>> >>>>
>> >>>> Looks like kcm is trying to reuse a work item whose last workqueue has
>> >>>> been destroyed without re-initing it. A work item needs to be
>> >>>> reinit'd.
>> >>>
>> >>> +kcm maintainers
>> >>
>> >> Can you try the fix below? There is no C reproducer so I can't verify it.
>> >
>> >
>> > Hi Cong,
>> >
>> > syzbot can now test proposed patches, see
>> > https://github.com/google/syzkaller/blob/master/docs/syzbot.md#communication-with-syzbot
>> > for details. Please give it a try.
>> >
>> >> diff --git a/net/kcm/kcmsock.c b/net/kcm/kcmsock.c
>> >> index af4e76ac88ff..7816f44c576a 100644
>> >> --- a/net/kcm/kcmsock.c
>> >> +++ b/net/kcm/kcmsock.c
>> >> @@ -1433,11 +1433,12 @@ static int kcm_attach(struct socket *sock,
>> >> struct socket *csock,
>> >> KCM_STATS_INCR(mux->stats.psock_attach);
>> >> mux->psocks_cnt++;
>> >> psock_now_avail(psock);
>> >> - spin_unlock_bh(&mux->lock);
>> >>
>> >> /* Schedule RX work in case there are already bytes queued */
>> >> strp_check_rcv(&psock->strp);
>> >>
>> >> + spin_unlock_bh(&mux->lock);
>> >> +
>> >> return 0;
>> >> }
>>
>>
>> Hi Cong,
>>
>> Was this ever merged? Is it still necessary?
>>
>
> syzbot is no longer hitting this bug for some reason but it's still there. Tom,
> it looks like you wrote the buggy code (it's yet another KCM bug, apparently);
> can you please look into it?
>
Yes. Thank you for the simple reproducer.
Tom
> I've put together a C reproducer that works on latest linux-next (next-20180309,
> commit 61530b14b059d). It works as an unprivileged user provided that KCM is
> enabled, and that KASAN is enabled so you see the use-after-free report:
>
> #include <linux/bpf.h>
> #include <linux/in.h>
> #include <linux/kcm.h>
> #include <sys/ioctl.h>
> #include <sys/socket.h>
> #include <sys/syscall.h>
> #include <unistd.h>
>
> int main()
> {
> union bpf_attr prog = {
> .prog_type = BPF_PROG_TYPE_SOCKET_FILTER,
> .insn_cnt = 2,
> .insns = (__u64)(__u64[]){ 0xb7, 0x95 },
> .license = (__u64)"",
> };
> int tcp_fd, bpf_fd, kcm_fd;
> struct sockaddr_in addr = {
> .sin_family = AF_INET,
> .sin_port = __constant_htons(3270),
> .sin_addr = { __constant_htonl(0x7f000001) }
> };
>
> tcp_fd = socket(AF_INET, SOCK_STREAM, 0);
> bind(tcp_fd, (void *)&addr, sizeof(addr));
> listen(tcp_fd, 1);
> tcp_fd = socket(AF_INET, SOCK_STREAM, 0);
> connect(tcp_fd, (void *)&addr, sizeof(addr));
> bpf_fd = syscall(__NR_bpf, BPF_PROG_LOAD, &prog, 48);
> kcm_fd = socket(AF_KCM, SOCK_SEQPACKET, 0);
> if (fork() == 0) {
> struct kcm_attach attach = { tcp_fd, bpf_fd };
>
> for (;;)
> ioctl(kcm_fd, SIOCKCMATTACH, &attach);
> } else {
> struct kcm_unattach unattach = { tcp_fd };
>
> for (;;)
> ioctl(kcm_fd, SIOCKCMUNATTACH, &unattach);
> }
> }