2019-08-09 21:50:54

by David Howells

[permalink] [raw]

Subject: [PATCH net] rxrpc: Fix local refcounting

---

Fix rxrpc_unuse_local() to handle a NULL local pointer as it can be called
on an unbound socket on which rx->local is not yet set.

The following reproduced (includes omitted):

int main(void)
{
socket(AF_RXRPC, SOCK_DGRAM, AF_INET);
return 0;
}

causes the following oops to occur:

BUG: kernel NULL pointer dereference, address: 0000000000000010
...
RIP: 0010:rxrpc_unuse_local+0x8/0x1b
...
Call Trace:
rxrpc_release+0x2b5/0x338
__sock_release+0x37/0xa1
sock_close+0x14/0x17
__fput+0x115/0x1e9
task_work_run+0x72/0x98
do_exit+0x51b/0xa7a
? __context_tracking_exit+0x4e/0x10e
do_group_exit+0xab/0xab
__x64_sys_exit_group+0x14/0x17
do_syscall_64+0x89/0x1d4
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Reported-by: [email protected]
Fixes: 730c5fd42c1e ("rxrpc: Fix local endpoint refcounting")
Signed-off-by: David Howells <[email protected]>
cc: Jeffrey Altman <[email protected]>
---

net/rxrpc/local_object.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
index 9798159ee65f..c9db3e762d8d 100644
--- a/net/rxrpc/local_object.c
+++ b/net/rxrpc/local_object.c
@@ -402,11 +402,13 @@ void rxrpc_unuse_local(struct rxrpc_local *local)
{
unsigned int au;

- au = atomic_dec_return(&local->active_users);
- if (au == 0)
- rxrpc_queue_local(local);
- else
- rxrpc_put_local(local);
+ if (local) {
+ au = atomic_dec_return(&local->active_users);
+ if (au == 0)
+ rxrpc_queue_local(local);
+ else
+ rxrpc_put_local(local);
+ }
}

/*

2019-08-09 22:36:14

by Jeffrey E Altman

[permalink] [raw]

Subject: Re: [PATCH net] rxrpc: Fix local refcounting

---

David,

Looks good to me.

You can add a Reviewed-by line.

Thanks.

Jeffrey Altman

On 8/9/2019 5:47 PM, David Howells wrote:
> Fix rxrpc_unuse_local() to handle a NULL local pointer as it can be called
> on an unbound socket on which rx->local is not yet set.
>
> The following reproduced (includes omitted):
>
> int main(void)
> {
> socket(AF_RXRPC, SOCK_DGRAM, AF_INET);
> return 0;
> }
>
> causes the following oops to occur:
>
> BUG: kernel NULL pointer dereference, address: 0000000000000010
> ...
> RIP: 0010:rxrpc_unuse_local+0x8/0x1b
> ...
> Call Trace:
> rxrpc_release+0x2b5/0x338
> __sock_release+0x37/0xa1
> sock_close+0x14/0x17
> __fput+0x115/0x1e9
> task_work_run+0x72/0x98
> do_exit+0x51b/0xa7a
> ? __context_tracking_exit+0x4e/0x10e
> do_group_exit+0xab/0xab
> __x64_sys_exit_group+0x14/0x17
> do_syscall_64+0x89/0x1d4
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Reported-by: [email protected]
> Fixes: 730c5fd42c1e ("rxrpc: Fix local endpoint refcounting")
> Signed-off-by: David Howells <[email protected]>
> cc: Jeffrey Altman <[email protected]>
> ---
>
> net/rxrpc/local_object.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/net/rxrpc/local_object.c b/net/rxrpc/local_object.c
> index 9798159ee65f..c9db3e762d8d 100644
> --- a/net/rxrpc/local_object.c
> +++ b/net/rxrpc/local_object.c
> @@ -402,11 +402,13 @@ void rxrpc_unuse_local(struct rxrpc_local *local)
> {
> unsigned int au;
>
> - au = atomic_dec_return(&local->active_users);
> - if (au == 0)
> - rxrpc_queue_local(local);
> - else
> - rxrpc_put_local(local);
> + if (local) {
> + au = atomic_dec_return(&local->active_users);
> + if (au == 0)
> + rxrpc_queue_local(local);
> + else
> + rxrpc_put_local(local);
> + }
> }
>
> /*
>

---

Attachments:

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2019-08-12 04:30:20

by David Miller

[permalink] [raw]

Subject: Re: [PATCH net] rxrpc: Fix local refcounting

---

From: David Howells <[email protected]>
Date: Fri, 09 Aug 2019 22:47:47 +0100

> Fix rxrpc_unuse_local() to handle a NULL local pointer as it can be called
> on an unbound socket on which rx->local is not yet set.
>
> The following reproduced (includes omitted):
>
> int main(void)
> {
> socket(AF_RXRPC, SOCK_DGRAM, AF_INET);
> return 0;
> }
>
> causes the following oops to occur:
>
> BUG: kernel NULL pointer dereference, address: 0000000000000010
> ...
> RIP: 0010:rxrpc_unuse_local+0x8/0x1b
> ...
> Call Trace:
> rxrpc_release+0x2b5/0x338
> __sock_release+0x37/0xa1
> sock_close+0x14/0x17
> __fput+0x115/0x1e9
> task_work_run+0x72/0x98
> do_exit+0x51b/0xa7a
> ? __context_tracking_exit+0x4e/0x10e
> do_group_exit+0xab/0xab
> __x64_sys_exit_group+0x14/0x17
> do_syscall_64+0x89/0x1d4
> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Reported-by: [email protected]
> Fixes: 730c5fd42c1e ("rxrpc: Fix local endpoint refcounting")
> Signed-off-by: David Howells <[email protected]>
> cc: Jeffrey Altman <[email protected]>

Applied.