* [PATCH] KVM: eventfd: fix NULL deref irqbypass consumer
@ 2017-01-05 9:05 Wanpeng Li
2017-01-05 10:24 ` Paolo Bonzini
0 siblings, 1 reply; 5+ messages in thread
From: Wanpeng Li @ 2017-01-05 9:05 UTC (permalink / raw)
To: linux-kernel, kvm
Cc: Paolo Bonzini, Radim Krčmář, Dmitry Vyukov, Wanpeng Li
From: Wanpeng Li <wanpeng.li@hotmail.com>
Reported syzkaller:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
IP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
PGD 0
Oops: 0002 [#1] SMP
CPU: 1 PID: 125 Comm: kworker/1:1 Not tainted 4.9.0+ #1
Workqueue: kvm-irqfd-cleanup irqfd_shutdown [kvm]
task: ffff9bbe0dfbb900 task.stack: ffffb61802014000
RIP: 0010:irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
Call Trace:
irqfd_shutdown+0x66/0xa0 [kvm]
process_one_work+0x16b/0x480
worker_thread+0x4b/0x500
kthread+0x101/0x140
? process_one_work+0x480/0x480
? kthread_create_on_node+0x60/0x60
ret_from_fork+0x25/0x30
RIP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass] RSP: ffffb61802017e20
CR2: 0000000000000008
The syzkaller folks reported a NULL pointer dereference that due to unregister
an consumer which fails registration before. The syzkaller creates two VMs w/
an equal eventfd occassionally. So the second VM fails to register an irqbypass
consumer. It will make irqfd as inactive and queue an workqueue work to shutdown
irqfd and unregister the irqbypass consumer when eventfd is closed. However, the
second consumer has been initialized though it fails registration. So the token
(same as the first VM's) is taken to unregister the consumer in the workqueue,
the consumer of the first VM is found and unregistered, then NULL deref incurred
in the path of deleting consumer from the consumers list.
#include <fcntl.h>
#include <pthread.h>
#include <setjmp.h>
#include <signal.h>
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
__thread int skip_segv;
__thread jmp_buf segv_env;
static void segv_handler(int sig, siginfo_t* info, void* uctx)
{
if (__atomic_load_n(&skip_segv, __ATOMIC_RELAXED))
_longjmp(segv_env, 1);
exit(sig);
}
static void install_segv_handler()
{
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sa.sa_sigaction = segv_handler;
sa.sa_flags = SA_NODEFER | SA_SIGINFO;
sigaction(SIGSEGV, &sa, NULL);
sigaction(SIGBUS, &sa, NULL);
}
#define NONFAILING(...) \
{ \
__atomic_fetch_add(&skip_segv, 1, __ATOMIC_SEQ_CST); \
if (_setjmp(segv_env) == 0) { \
__VA_ARGS__; \
} \
__atomic_fetch_sub(&skip_segv, 1, __ATOMIC_SEQ_CST); \
}
static uintptr_t execute_syscall(int nr, uintptr_t a0, uintptr_t a1,
uintptr_t a2, uintptr_t a3,
uintptr_t a4, uintptr_t a5,
uintptr_t a6, uintptr_t a7,
uintptr_t a8)
{
return syscall(nr, a0, a1, a2, a3, a4, a5);
}
long r[28];
void* thr(void* arg)
{
switch ((long)arg) {
case 0:
r[0] =
execute_syscall(__NR_mmap, 0x20000000ul, 0xd000ul, 0x3ul,
0x32ul, 0xfffffffffffffffful, 0x0ul, 0, 0, 0);
break;
case 1:
r[2] = syscall(__NR_open, "/dev/kvm", 0x40042ul, 0, 0, 0, 0, 0, 0);
break;
case 2:
r[3] = execute_syscall(__NR_ioctl, r[2], 0xae01ul, 0x0ul, 0, 0, 0,
0, 0, 0);
break;
case 3:
r[4] = execute_syscall(__NR_ioctl, r[3], 0xae41ul, 0x3fful, 0, 0, 0,
0, 0, 0);
break;
case 4:
r[5] = execute_syscall(__NR_ioctl, r[4], 0xae9aul, 0, 0, 0, 0, 0, 0,
0);
break;
case 5:
r[6] = execute_syscall(__NR_eventfd2, 0x8ul, 0x801ul, 0, 0, 0, 0, 0,
0, 0);
break;
case 6:
NONFAILING(*(uint32_t*)0x2000c000 = r[6]);
NONFAILING(*(uint32_t*)0x2000c004 = (uint32_t)0x98cd);
NONFAILING(*(uint32_t*)0x2000c008 = (uint32_t)0x0);
NONFAILING(*(uint32_t*)0x2000c00c = (uint32_t)0xffffffffffffffff);
NONFAILING(*(uint8_t*)0x2000c010 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c011 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c012 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c013 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c014 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c015 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c016 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c017 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c018 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c019 = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c01a = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c01b = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c01c = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c01d = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c01e = (uint8_t)0x0);
NONFAILING(*(uint8_t*)0x2000c01f = (uint8_t)0x0);
r[27] = execute_syscall(__NR_ioctl, r[3], 0x4020ae76ul,
0x2000c000ul, 0, 0, 0, 0, 0, 0);
break;
}
return 0;
}
int main()
{
long i;
pthread_t th[14];
install_segv_handler();
memset(r, -1, sizeof(r));
srand(getpid());
for (i = 0; i < 7; i++) {
pthread_create(&th[i], 0, thr, (void*)i);
usleep(10000);
}
for (i = 0; i < 7; i++) {
pthread_create(&th[7 + i], 0, thr, (void*)i);
if (rand() % 2)
usleep(rand() % 10000);
}
usleep(100000);
return 0;
}
This patch fix it by destroying the consumer which just fails registration.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
---
virt/kvm/eventfd.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
index a29786d..eeaf056 100644
--- a/virt/kvm/eventfd.c
+++ b/virt/kvm/eventfd.c
@@ -415,9 +415,15 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
irqfd->consumer.start = kvm_arch_irq_bypass_start;
ret = irq_bypass_register_consumer(&irqfd->consumer);
- if (ret)
+ if (ret) {
pr_info("irq bypass consumer (token %p) registration fails: %d\n",
irqfd->consumer.token, ret);
+ irqfd->consumer.token = NULL;
+ irqfd->consumer.add_producer = NULL;
+ irqfd->consumer.del_producer = NULL;
+ irqfd->consumer.stop = NULL;
+ irqfd->consumer.start = NULL;
+ }
}
#endif
--
2.7.4
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: eventfd: fix NULL deref irqbypass consumer
2017-01-05 9:05 [PATCH] KVM: eventfd: fix NULL deref irqbypass consumer Wanpeng Li
@ 2017-01-05 10:24 ` Paolo Bonzini
2017-01-05 10:51 ` Wanpeng Li
2017-01-05 16:01 ` Alex Williamson
0 siblings, 2 replies; 5+ messages in thread
From: Paolo Bonzini @ 2017-01-05 10:24 UTC (permalink / raw)
To: Wanpeng Li, linux-kernel, kvm
Cc: Radim Krčmář, Dmitry Vyukov, Wanpeng Li, Alex Williamson
On 05/01/2017 10:05, Wanpeng Li wrote:
> From: Wanpeng Li <wanpeng.li@hotmail.com>
>
> Reported syzkaller:
>
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> IP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
> PGD 0
>
> Oops: 0002 [#1] SMP
> CPU: 1 PID: 125 Comm: kworker/1:1 Not tainted 4.9.0+ #1
> Workqueue: kvm-irqfd-cleanup irqfd_shutdown [kvm]
> task: ffff9bbe0dfbb900 task.stack: ffffb61802014000
> RIP: 0010:irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
> Call Trace:
> irqfd_shutdown+0x66/0xa0 [kvm]
> process_one_work+0x16b/0x480
> worker_thread+0x4b/0x500
> kthread+0x101/0x140
> ? process_one_work+0x480/0x480
> ? kthread_create_on_node+0x60/0x60
> ret_from_fork+0x25/0x30
> RIP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass] RSP: ffffb61802017e20
> CR2: 0000000000000008
>
> The syzkaller folks reported a NULL pointer dereference that due to unregister
> an consumer which fails registration before. The syzkaller creates two VMs w/
> an equal eventfd occassionally. So the second VM fails to register an irqbypass
> consumer. It will make irqfd as inactive and queue an workqueue work to shutdown
> irqfd and unregister the irqbypass consumer when eventfd is closed. However, the
> second consumer has been initialized though it fails registration. So the token
> (same as the first VM's) is taken to unregister the consumer in the workqueue,
> the consumer of the first VM is found and unregistered, then NULL deref incurred
> in the path of deleting consumer from the consumers list.
Thanks Wanpend!
However, I'm wondering if we should improve the API instead. Maybe the
token should be passed to irq_bypass_register_{producer,consumer} and
only assigned if the functions succeed. Alex, what do you think?
Thanks,
Paolo
>
> diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> index a29786d..eeaf056 100644
> --- a/virt/kvm/eventfd.c
> +++ b/virt/kvm/eventfd.c
> @@ -415,9 +415,15 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
> irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
> irqfd->consumer.start = kvm_arch_irq_bypass_start;
> ret = irq_bypass_register_consumer(&irqfd->consumer);
> - if (ret)
> + if (ret) {
> pr_info("irq bypass consumer (token %p) registration fails: %d\n",
> irqfd->consumer.token, ret);
> + irqfd->consumer.token = NULL;
> + irqfd->consumer.add_producer = NULL;
> + irqfd->consumer.del_producer = NULL;
> + irqfd->consumer.stop = NULL;
> + irqfd->consumer.start = NULL;
> + }
> }
> #endif
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: eventfd: fix NULL deref irqbypass consumer
2017-01-05 10:24 ` Paolo Bonzini
@ 2017-01-05 10:51 ` Wanpeng Li
2017-01-05 16:01 ` Alex Williamson
1 sibling, 0 replies; 5+ messages in thread
From: Wanpeng Li @ 2017-01-05 10:51 UTC (permalink / raw)
To: Paolo Bonzini
Cc: linux-kernel, kvm, Radim Krčmář,
Dmitry Vyukov, Wanpeng Li, Alex Williamson
2017-01-05 18:24 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>
>
> On 05/01/2017 10:05, Wanpeng Li wrote:
>> From: Wanpeng Li <wanpeng.li@hotmail.com>
>>
>> Reported syzkaller:
>>
>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
>> IP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
>> PGD 0
>>
>> Oops: 0002 [#1] SMP
>> CPU: 1 PID: 125 Comm: kworker/1:1 Not tainted 4.9.0+ #1
>> Workqueue: kvm-irqfd-cleanup irqfd_shutdown [kvm]
>> task: ffff9bbe0dfbb900 task.stack: ffffb61802014000
>> RIP: 0010:irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
>> Call Trace:
>> irqfd_shutdown+0x66/0xa0 [kvm]
>> process_one_work+0x16b/0x480
>> worker_thread+0x4b/0x500
>> kthread+0x101/0x140
>> ? process_one_work+0x480/0x480
>> ? kthread_create_on_node+0x60/0x60
>> ret_from_fork+0x25/0x30
>> RIP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass] RSP: ffffb61802017e20
>> CR2: 0000000000000008
>>
>> The syzkaller folks reported a NULL pointer dereference that due to unregister
>> an consumer which fails registration before. The syzkaller creates two VMs w/
>> an equal eventfd occassionally. So the second VM fails to register an irqbypass
>> consumer. It will make irqfd as inactive and queue an workqueue work to shutdown
>> irqfd and unregister the irqbypass consumer when eventfd is closed. However, the
>> second consumer has been initialized though it fails registration. So the token
>> (same as the first VM's) is taken to unregister the consumer in the workqueue,
>> the consumer of the first VM is found and unregistered, then NULL deref incurred
>> in the path of deleting consumer from the consumers list.
>
> Thanks Wanpend!
NP. :)
>
> However, I'm wondering if we should improve the API instead. Maybe the
> token should be passed to irq_bypass_register_{producer,consumer} and
> only assigned if the functions succeed. Alex, what do you think?
Yeah, I can continue to improve the patch if we reach an agreement with Alex. :)
Regards,
Wanpeng Li
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: eventfd: fix NULL deref irqbypass consumer
2017-01-05 10:24 ` Paolo Bonzini
2017-01-05 10:51 ` Wanpeng Li
@ 2017-01-05 16:01 ` Alex Williamson
2017-01-06 1:46 ` Wanpeng Li
1 sibling, 1 reply; 5+ messages in thread
From: Alex Williamson @ 2017-01-05 16:01 UTC (permalink / raw)
To: Paolo Bonzini
Cc: Wanpeng Li, linux-kernel, kvm, Radim Krčmář,
Dmitry Vyukov, Wanpeng Li
On Thu, 5 Jan 2017 11:24:08 +0100
Paolo Bonzini <pbonzini@redhat.com> wrote:
> On 05/01/2017 10:05, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpeng.li@hotmail.com>
> >
> > Reported syzkaller:
> >
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
> > IP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
> > PGD 0
> >
> > Oops: 0002 [#1] SMP
> > CPU: 1 PID: 125 Comm: kworker/1:1 Not tainted 4.9.0+ #1
> > Workqueue: kvm-irqfd-cleanup irqfd_shutdown [kvm]
> > task: ffff9bbe0dfbb900 task.stack: ffffb61802014000
> > RIP: 0010:irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
> > Call Trace:
> > irqfd_shutdown+0x66/0xa0 [kvm]
> > process_one_work+0x16b/0x480
> > worker_thread+0x4b/0x500
> > kthread+0x101/0x140
> > ? process_one_work+0x480/0x480
> > ? kthread_create_on_node+0x60/0x60
> > ret_from_fork+0x25/0x30
> > RIP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass] RSP: ffffb61802017e20
> > CR2: 0000000000000008
> >
> > The syzkaller folks reported a NULL pointer dereference that due to unregister
> > an consumer which fails registration before. The syzkaller creates two VMs w/
> > an equal eventfd occassionally. So the second VM fails to register an irqbypass
> > consumer. It will make irqfd as inactive and queue an workqueue work to shutdown
> > irqfd and unregister the irqbypass consumer when eventfd is closed. However, the
> > second consumer has been initialized though it fails registration. So the token
> > (same as the first VM's) is taken to unregister the consumer in the workqueue,
> > the consumer of the first VM is found and unregistered, then NULL deref incurred
> > in the path of deleting consumer from the consumers list.
>
> Thanks Wanpend!
>
> However, I'm wondering if we should improve the API instead. Maybe the
> token should be passed to irq_bypass_register_{producer,consumer} and
> only assigned if the functions succeed. Alex, what do you think?
Yes, I agree, we should improve the API rather than placing the burden
on the caller to cleanup on failure. I'm actually wondering why
irq_bypass_unregister_consumer() looks for the consumer entry based on
token matching rather than the consumer pointer itself. For instance,
doesn't something like this (untested) solve it?
diff --git a/virt/lib/irqbypass.c b/virt/lib/irqbypass.c
index 52abac4..6d2fcd6 100644
--- a/virt/lib/irqbypass.c
+++ b/virt/lib/irqbypass.c
@@ -195,7 +195,7 @@ int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer)
mutex_lock(&lock);
list_for_each_entry(tmp, &consumers, node) {
- if (tmp->token == consumer->token) {
+ if (tmp->token == consumer->token || tmp == consumer) {
mutex_unlock(&lock);
module_put(THIS_MODULE);
return -EBUSY;
@@ -245,7 +245,7 @@ void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer)
mutex_lock(&lock);
list_for_each_entry(tmp, &consumers, node) {
- if (tmp->token != consumer->token)
+ if (tmp != consumer)
continue;
list_for_each_entry(producer, &producers, node) {
> > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
> > index a29786d..eeaf056 100644
> > --- a/virt/kvm/eventfd.c
> > +++ b/virt/kvm/eventfd.c
> > @@ -415,9 +415,15 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
> > irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
> > irqfd->consumer.start = kvm_arch_irq_bypass_start;
> > ret = irq_bypass_register_consumer(&irqfd->consumer);
> > - if (ret)
> > + if (ret) {
> > pr_info("irq bypass consumer (token %p) registration fails: %d\n",
> > irqfd->consumer.token, ret);
> > + irqfd->consumer.token = NULL;
> > + irqfd->consumer.add_producer = NULL;
> > + irqfd->consumer.del_producer = NULL;
> > + irqfd->consumer.stop = NULL;
> > + irqfd->consumer.start = NULL;
> > + }
> > }
> > #endif
> >
> >
> --
> To unsubscribe from this list: send the line "unsubscribe kvm" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] KVM: eventfd: fix NULL deref irqbypass consumer
2017-01-05 16:01 ` Alex Williamson
@ 2017-01-06 1:46 ` Wanpeng Li
0 siblings, 0 replies; 5+ messages in thread
From: Wanpeng Li @ 2017-01-06 1:46 UTC (permalink / raw)
To: Alex Williamson
Cc: Paolo Bonzini, linux-kernel, kvm, Radim Krčmář,
Dmitry Vyukov, Wanpeng Li
2017-01-06 0:01 GMT+08:00 Alex Williamson <alex.williamson@redhat.com>:
> On Thu, 5 Jan 2017 11:24:08 +0100
> Paolo Bonzini <pbonzini@redhat.com> wrote:
>
>> On 05/01/2017 10:05, Wanpeng Li wrote:
>> > From: Wanpeng Li <wanpeng.li@hotmail.com>
>> >
>> > Reported syzkaller:
>> >
>> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
>> > IP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
>> > PGD 0
>> >
>> > Oops: 0002 [#1] SMP
>> > CPU: 1 PID: 125 Comm: kworker/1:1 Not tainted 4.9.0+ #1
>> > Workqueue: kvm-irqfd-cleanup irqfd_shutdown [kvm]
>> > task: ffff9bbe0dfbb900 task.stack: ffffb61802014000
>> > RIP: 0010:irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass]
>> > Call Trace:
>> > irqfd_shutdown+0x66/0xa0 [kvm]
>> > process_one_work+0x16b/0x480
>> > worker_thread+0x4b/0x500
>> > kthread+0x101/0x140
>> > ? process_one_work+0x480/0x480
>> > ? kthread_create_on_node+0x60/0x60
>> > ret_from_fork+0x25/0x30
>> > RIP: irq_bypass_unregister_consumer+0x9d/0xb70 [irqbypass] RSP: ffffb61802017e20
>> > CR2: 0000000000000008
>> >
>> > The syzkaller folks reported a NULL pointer dereference that due to unregister
>> > an consumer which fails registration before. The syzkaller creates two VMs w/
>> > an equal eventfd occassionally. So the second VM fails to register an irqbypass
>> > consumer. It will make irqfd as inactive and queue an workqueue work to shutdown
>> > irqfd and unregister the irqbypass consumer when eventfd is closed. However, the
>> > second consumer has been initialized though it fails registration. So the token
>> > (same as the first VM's) is taken to unregister the consumer in the workqueue,
>> > the consumer of the first VM is found and unregistered, then NULL deref incurred
>> > in the path of deleting consumer from the consumers list.
>>
>> Thanks Wanpend!
>>
>> However, I'm wondering if we should improve the API instead. Maybe the
>> token should be passed to irq_bypass_register_{producer,consumer} and
>> only assigned if the functions succeed. Alex, what do you think?
>
> Yes, I agree, we should improve the API rather than placing the burden
> on the caller to cleanup on failure. I'm actually wondering why
> irq_bypass_unregister_consumer() looks for the consumer entry based on
> token matching rather than the consumer pointer itself. For instance,
> doesn't something like this (untested) solve it?
Thanks for the great proposal Alex, it works. :) I just sent out v2.
Regards,
Wanpeng Li
>
> diff --git a/virt/lib/irqbypass.c b/virt/lib/irqbypass.c
> index 52abac4..6d2fcd6 100644
> --- a/virt/lib/irqbypass.c
> +++ b/virt/lib/irqbypass.c
> @@ -195,7 +195,7 @@ int irq_bypass_register_consumer(struct irq_bypass_consumer *consumer)
> mutex_lock(&lock);
>
> list_for_each_entry(tmp, &consumers, node) {
> - if (tmp->token == consumer->token) {
> + if (tmp->token == consumer->token || tmp == consumer) {
> mutex_unlock(&lock);
> module_put(THIS_MODULE);
> return -EBUSY;
> @@ -245,7 +245,7 @@ void irq_bypass_unregister_consumer(struct irq_bypass_consumer *consumer)
> mutex_lock(&lock);
>
> list_for_each_entry(tmp, &consumers, node) {
> - if (tmp->token != consumer->token)
> + if (tmp != consumer)
> continue;
>
> list_for_each_entry(producer, &producers, node) {
>
>
>> > diff --git a/virt/kvm/eventfd.c b/virt/kvm/eventfd.c
>> > index a29786d..eeaf056 100644
>> > --- a/virt/kvm/eventfd.c
>> > +++ b/virt/kvm/eventfd.c
>> > @@ -415,9 +415,15 @@ kvm_irqfd_assign(struct kvm *kvm, struct kvm_irqfd *args)
>> > irqfd->consumer.stop = kvm_arch_irq_bypass_stop;
>> > irqfd->consumer.start = kvm_arch_irq_bypass_start;
>> > ret = irq_bypass_register_consumer(&irqfd->consumer);
>> > - if (ret)
>> > + if (ret) {
>> > pr_info("irq bypass consumer (token %p) registration fails: %d\n",
>> > irqfd->consumer.token, ret);
>> > + irqfd->consumer.token = NULL;
>> > + irqfd->consumer.add_producer = NULL;
>> > + irqfd->consumer.del_producer = NULL;
>> > + irqfd->consumer.stop = NULL;
>> > + irqfd->consumer.start = NULL;
>> > + }
>> > }
>> > #endif
>> >
>> >
>> --
>> To unsubscribe from this list: send the line "unsubscribe kvm" in
>> the body of a message to majordomo@vger.kernel.org
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>
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2017-01-06 1:46 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-05 9:05 [PATCH] KVM: eventfd: fix NULL deref irqbypass consumer Wanpeng Li
2017-01-05 10:24 ` Paolo Bonzini
2017-01-05 10:51 ` Wanpeng Li
2017-01-05 16:01 ` Alex Williamson
2017-01-06 1:46 ` Wanpeng Li
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