* [PATCH net] net/9p: fix issue of list_del corruption in p9_fd_cancel()
@ 2022-11-10 12:26 Zhengchao Shao
2022-11-10 12:51 ` asmadeus
0 siblings, 1 reply; 4+ messages in thread
From: Zhengchao Shao @ 2022-11-10 12:26 UTC (permalink / raw)
To: v9fs-developer, netdev, ericvh, lucho, asmadeus, linux_oss,
edumazet, kuba, pabeni
Cc: weiyongjun1, yuehaibing, shaozhengchao
Syz reported the following issue:
kernel BUG at lib/list_debug.c:53!
invalid opcode: 0000 [#1] PREEMPT SMP KASAN
RIP: 0010:__list_del_entry_valid.cold+0x5c/0x72
Call Trace:
<TASK>
p9_fd_cancel+0xb1/0x270
p9_client_rpc+0x8ea/0xba0
p9_client_create+0x9c0/0xed0
v9fs_session_init+0x1e0/0x1620
v9fs_mount+0xba/0xb80
legacy_get_tree+0x103/0x200
vfs_get_tree+0x89/0x2d0
path_mount+0x4c0/0x1ac0
__x64_sys_mount+0x33b/0x430
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x46/0xb0
</TASK>
The process is as follows:
Thread A: Thread B:
p9_poll_workfn() p9_client_create()
... ...
p9_conn_cancel() p9_fd_cancel()
list_del() ...
... list_del() //list_del
corruption
There is no lock protection when deleting list in p9_conn_cancel(). After
deleting list in Thread A, thread B will delete the same list again. It
will cause issue of list_del corruption.
Fixes: 52f1c45dde91 ("9p: trans_fd/p9_conn_cancel: drop client lock earlier")
Reported-by: syzbot+9b69b8d10ab4a7d88056@syzkaller.appspotmail.com
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
---
v2: set req status when removing list
---
net/9p/trans_fd.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
index 56a186768750..bd28e63d7666 100644
--- a/net/9p/trans_fd.c
+++ b/net/9p/trans_fd.c
@@ -202,9 +202,11 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
list_move(&req->req_list, &cancel_list);
+ req->status = REQ_STATUS_ERROR;
}
list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
list_move(&req->req_list, &cancel_list);
+ req->status = REQ_STATUS_ERROR;
}
spin_unlock(&m->req_lock);
--
2.17.1
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH net] net/9p: fix issue of list_del corruption in p9_fd_cancel()
2022-11-10 12:26 [PATCH net] net/9p: fix issue of list_del corruption in p9_fd_cancel() Zhengchao Shao
@ 2022-11-10 12:51 ` asmadeus
2022-11-11 1:23 ` shaozhengchao
0 siblings, 1 reply; 4+ messages in thread
From: asmadeus @ 2022-11-10 12:51 UTC (permalink / raw)
To: Zhengchao Shao
Cc: v9fs-developer, netdev, ericvh, lucho, linux_oss, edumazet, kuba,
pabeni, weiyongjun1, yuehaibing
Zhengchao Shao wrote on Thu, Nov 10, 2022 at 08:26:06PM +0800:
> Syz reported the following issue:
> kernel BUG at lib/list_debug.c:53!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> RIP: 0010:__list_del_entry_valid.cold+0x5c/0x72
> Call Trace:
> <TASK>
> p9_fd_cancel+0xb1/0x270
> p9_client_rpc+0x8ea/0xba0
> p9_client_create+0x9c0/0xed0
> v9fs_session_init+0x1e0/0x1620
> v9fs_mount+0xba/0xb80
> legacy_get_tree+0x103/0x200
> vfs_get_tree+0x89/0x2d0
> path_mount+0x4c0/0x1ac0
> __x64_sys_mount+0x33b/0x430
> do_syscall_64+0x35/0x80
> entry_SYSCALL_64_after_hwframe+0x46/0xb0
> </TASK>
>
> The process is as follows:
> Thread A: Thread B:
> p9_poll_workfn() p9_client_create()
> ... ...
> p9_conn_cancel() p9_fd_cancel()
> list_del() ...
> ... list_del() //list_del
> corruption
> There is no lock protection when deleting list in p9_conn_cancel(). After
> deleting list in Thread A, thread B will delete the same list again. It
> will cause issue of list_del corruption.
Thanks!
I'd add a couple of lines here describing the actual fix.
Something like this?
---
Setting req->status to REQ_STATUS_ERROR under lock prevents other
cleanup paths from trying to manipulate req_list.
The other thread can safely check req->status because it still holds a
reference to req at this point.
---
With that out of the way, it's a good idea; I didn't remember that
p9_fd_cancel (and cancelled) check for req status before acting on it.
This really feels like whack-a-mole, but I'd say this is one step
better.
Please tell me if you want to send a v2 with your words, or I'll just
pick this up with my suggestion and submit to Linus in a week-ish after
testing. No point in waiting a full cycle for this.
> Fixes: 52f1c45dde91 ("9p: trans_fd/p9_conn_cancel: drop client lock earlier")
> Reported-by: syzbot+9b69b8d10ab4a7d88056@syzkaller.appspotmail.com
> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
> ---
> v2: set req status when removing list
(I don't recall seeing a v1?)
> ---
> net/9p/trans_fd.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
> index 56a186768750..bd28e63d7666 100644
> --- a/net/9p/trans_fd.c
> +++ b/net/9p/trans_fd.c
> @@ -202,9 +202,11 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
>
> list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
> list_move(&req->req_list, &cancel_list);
> + req->status = REQ_STATUS_ERROR;
> }
> list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
> list_move(&req->req_list, &cancel_list);
> + req->status = REQ_STATUS_ERROR;
> }
>
> spin_unlock(&m->req_lock);
--
Dominique
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] net/9p: fix issue of list_del corruption in p9_fd_cancel()
2022-11-10 12:51 ` asmadeus
@ 2022-11-11 1:23 ` shaozhengchao
2022-11-11 2:12 ` asmadeus
0 siblings, 1 reply; 4+ messages in thread
From: shaozhengchao @ 2022-11-11 1:23 UTC (permalink / raw)
To: asmadeus
Cc: v9fs-developer, netdev, ericvh, lucho, linux_oss, edumazet, kuba,
pabeni, weiyongjun1, yuehaibing
On 2022/11/10 20:51, asmadeus@codewreck.org wrote:
> Zhengchao Shao wrote on Thu, Nov 10, 2022 at 08:26:06PM +0800:
>> Syz reported the following issue:
>> kernel BUG at lib/list_debug.c:53!
>> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
>> RIP: 0010:__list_del_entry_valid.cold+0x5c/0x72
>> Call Trace:
>> <TASK>
>> p9_fd_cancel+0xb1/0x270
>> p9_client_rpc+0x8ea/0xba0
>> p9_client_create+0x9c0/0xed0
>> v9fs_session_init+0x1e0/0x1620
>> v9fs_mount+0xba/0xb80
>> legacy_get_tree+0x103/0x200
>> vfs_get_tree+0x89/0x2d0
>> path_mount+0x4c0/0x1ac0
>> __x64_sys_mount+0x33b/0x430
>> do_syscall_64+0x35/0x80
>> entry_SYSCALL_64_after_hwframe+0x46/0xb0
>> </TASK>
>>
>> The process is as follows:
>> Thread A: Thread B:
>> p9_poll_workfn() p9_client_create()
>> ... ...
>> p9_conn_cancel() p9_fd_cancel()
>> list_del() ...
>> ... list_del() //list_del
>> corruption
>> There is no lock protection when deleting list in p9_conn_cancel(). After
>> deleting list in Thread A, thread B will delete the same list again. It
>> will cause issue of list_del corruption.
>
> Thanks!
>
> I'd add a couple of lines here describing the actual fix.
> Something like this?
> ---
> Setting req->status to REQ_STATUS_ERROR under lock prevents other
> cleanup paths from trying to manipulate req_list.
> The other thread can safely check req->status because it still holds a
> reference to req at this point.
> ---
>
> With that out of the way, it's a good idea; I didn't remember that
> p9_fd_cancel (and cancelled) check for req status before acting on it.
> This really feels like whack-a-mole, but I'd say this is one step
> better.
>
> Please tell me if you want to send a v2 with your words, or I'll just
> pick this up with my suggestion and submit to Linus in a week-ish after
> testing. No point in waiting a full cycle for this.
>
>
Hi Dominique:
Thank you for your review. Your suggestion looks good to me, and
please add your suggestion. :)
>> Fixes: 52f1c45dde91 ("9p: trans_fd/p9_conn_cancel: drop client lock earlier")
>> Reported-by: syzbot+9b69b8d10ab4a7d88056@syzkaller.appspotmail.com
>> Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
>> ---
>> v2: set req status when removing list
>
> (I don't recall seeing a v1?)
>
Sorry, please ignore this notes.
>> ---
>> net/9p/trans_fd.c | 2 ++
>> 1 file changed, 2 insertions(+)
>>
>> diff --git a/net/9p/trans_fd.c b/net/9p/trans_fd.c
>> index 56a186768750..bd28e63d7666 100644
>> --- a/net/9p/trans_fd.c
>> +++ b/net/9p/trans_fd.c
>> @@ -202,9 +202,11 @@ static void p9_conn_cancel(struct p9_conn *m, int err)
>>
>> list_for_each_entry_safe(req, rtmp, &m->req_list, req_list) {
>> list_move(&req->req_list, &cancel_list);
>> + req->status = REQ_STATUS_ERROR;
>> }
>> list_for_each_entry_safe(req, rtmp, &m->unsent_req_list, req_list) {
>> list_move(&req->req_list, &cancel_list);
>> + req->status = REQ_STATUS_ERROR;
>> }
>>
>> spin_unlock(&m->req_lock);
>
> --
> Dominique
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH net] net/9p: fix issue of list_del corruption in p9_fd_cancel()
2022-11-11 1:23 ` shaozhengchao
@ 2022-11-11 2:12 ` asmadeus
0 siblings, 0 replies; 4+ messages in thread
From: asmadeus @ 2022-11-11 2:12 UTC (permalink / raw)
To: shaozhengchao
Cc: v9fs-developer, netdev, ericvh, lucho, linux_oss, edumazet, kuba,
pabeni, weiyongjun1, yuehaibing
shaozhengchao wrote on Fri, Nov 11, 2022 at 09:23:12AM +0800:
> > Please tell me if you want to send a v2 with your words, or I'll just
> > pick this up with my suggestion and submit to Linus in a week-ish after
> > testing. No point in waiting a full cycle for this.
>
> Thank you for your review. Your suggestion looks good to me, and
> please add your suggestion. :)
I've done quick checks with a tcp server and pushed it for next.
I'll try to remember to send it to Linus mid next-week.
--
Dominique
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2022-11-11 2:12 UTC | newest]
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2022-11-10 12:26 [PATCH net] net/9p: fix issue of list_del corruption in p9_fd_cancel() Zhengchao Shao
2022-11-10 12:51 ` asmadeus
2022-11-11 1:23 ` shaozhengchao
2022-11-11 2:12 ` asmadeus
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