* [PATCH] sunrpc: bug on rpc_task_set_client when no client is present.
@ 2021-10-18 12:38 Thiago Rafael Becker
2021-10-20 19:04 ` Trond Myklebust
0 siblings, 1 reply; 3+ messages in thread
From: Thiago Rafael Becker @ 2021-10-18 12:38 UTC (permalink / raw)
To: linux-nfs
Cc: Thiago Rafael Becker, Trond Myklebust, Anna Schumaker,
J . Bruce Fields, Chuck Lever, David S . Miller, Jakub Kicinski,
netdev, linux-kernel, Thiago Rafael Becker
If we pass a NULL client to rpc_task_set_client and no client is
attached to the task, then the kernel will crash later. Antecipate the
crash by checking if a client is available for the task.
Signed-off-by: Thiago Rafael Becker <trbecker@gmail.com>
---
net/sunrpc/clnt.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
index f056ff931444..ccbc9a9715da 100644
--- a/net/sunrpc/clnt.c
+++ b/net/sunrpc/clnt.c
@@ -1076,7 +1076,7 @@ void rpc_task_set_transport(struct rpc_task *task, struct rpc_clnt *clnt)
static
void rpc_task_set_client(struct rpc_task *task, struct rpc_clnt *clnt)
{
-
+ BUG_ON(clnt == NULL && task->tk_client == NULL);
if (clnt != NULL) {
rpc_task_set_transport(task, clnt);
task->tk_client = clnt;
--
2.31.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] sunrpc: bug on rpc_task_set_client when no client is present.
2021-10-18 12:38 [PATCH] sunrpc: bug on rpc_task_set_client when no client is present Thiago Rafael Becker
@ 2021-10-20 19:04 ` Trond Myklebust
2021-10-20 20:20 ` Thiago Rafael Becker
0 siblings, 1 reply; 3+ messages in thread
From: Trond Myklebust @ 2021-10-20 19:04 UTC (permalink / raw)
To: trbecker, linux-nfs
Cc: tbecker, davem, chuck.lever, linux-kernel, netdev, kuba, bfields,
anna.schumaker
On Mon, 2021-10-18 at 09:38 -0300, Thiago Rafael Becker wrote:
> If we pass a NULL client to rpc_task_set_client and no client is
> attached to the task, then the kernel will crash later. Antecipate
> the
> crash by checking if a client is available for the task.
>
> Signed-off-by: Thiago Rafael Becker <trbecker@gmail.com>
> ---
> net/sunrpc/clnt.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c
> index f056ff931444..ccbc9a9715da 100644
> --- a/net/sunrpc/clnt.c
> +++ b/net/sunrpc/clnt.c
> @@ -1076,7 +1076,7 @@ void rpc_task_set_transport(struct rpc_task
> *task, struct rpc_clnt *clnt)
> static
> void rpc_task_set_client(struct rpc_task *task, struct rpc_clnt
> *clnt)
> {
> -
> + BUG_ON(clnt == NULL && task->tk_client == NULL);
> if (clnt != NULL) {
> rpc_task_set_transport(task, clnt);
> task->tk_client = clnt;
I'm not seeing the point of this BUG_ON(). Why not just change this
code to not check for clnt == NULL, and let the thing Oops when it
tries to dereference clnt?
--
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] sunrpc: bug on rpc_task_set_client when no client is present.
2021-10-20 19:04 ` Trond Myklebust
@ 2021-10-20 20:20 ` Thiago Rafael Becker
0 siblings, 0 replies; 3+ messages in thread
From: Thiago Rafael Becker @ 2021-10-20 20:20 UTC (permalink / raw)
To: Trond Myklebust
Cc: linux-nfs, tbecker, davem, chuck.lever, linux-kernel, netdev,
kuba, bfields, anna.schumaker
On Wed, Oct 20, 2021 at 07:04:35PM +0000, Trond Myklebust wrote:
Hello,
> I'm not seeing the point of this BUG_ON(). Why not just change this
> code to not check for clnt == NULL, and let the thing Oops when it
> tries to dereference clnt?
This was changed in 58f9612c6ea85, prior to that, this was not tested. I'm
not sure why this test exists, the only reason I can imagine is to keep
the previous task's rpc_client in case the new client is NULL. Decided
to go conservative on this, and BUG_ON() when no client is available.
Inside the linux source, I don't see how this may happen unless the code
has a bug, so I think it's possible to remove this test.
-- Thiago
> --
> Trond Myklebust
> Linux NFS client maintainer, Hammerspace
> trond.myklebust@hammerspace.com
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
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2021-10-18 12:38 [PATCH] sunrpc: bug on rpc_task_set_client when no client is present Thiago Rafael Becker
2021-10-20 19:04 ` Trond Myklebust
2021-10-20 20:20 ` Thiago Rafael Becker
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