[PATCH] infiniband: remove WARN that is not kernel bug

[PATCH] infiniband: remove WARN that is not kernel bug

[Dmitry Vyukov]

WARNINGs mean kernel bugs.
The one in ucma_write() points to user programming error
or a malicious attempt. This is not a kernel bug, remove it.

BUG/WARNs that are not kernel bugs hinder automated testing effots.

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Sean Hefty <sean.hefty@intel.com>
Cc: Hal Rosenstock <hal.rosenstock@gmail.com>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: linux-rdma@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: syzkaller@googlegroups.com
---
 drivers/infiniband/core/ucma.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/ucma.c b/drivers/infiniband/core/ucma.c
index 9520154..ff60373 100644
--- a/drivers/infiniband/core/ucma.c
+++ b/drivers/infiniband/core/ucma.c
@@ -1584,7 +1584,7 @@ static ssize_t ucma_write(struct file *filp, const char __user *buf,
 	struct rdma_ucm_cmd_hdr hdr;
 	ssize_t ret;
 
-	if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
+	if (!ib_safe_file_access(filp))
 		return -EACCES;
 
 	if (len < sizeof(hdr))
-- 
2.8.0.rc3.226.g39d4020

Re: [PATCH] infiniband: remove WARN that is not kernel bug

[Valdis.Kletnieks]

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On Fri, 18 Nov 2016 12:24:37 +0100, Dmitry Vyukov said:
> WARNINGs mean kernel bugs.
> The one in ucma_write() points to user programming error
> or a malicious attempt. This is not a kernel bug, remove it.

> -	if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
> +	if (!ib_safe_file_access(filp))
>  		return -EACCES;

In that case, wouldn't this be better?

	if (!ib_safe_file_access(filp)) {
		printk_once("Process %d (%s) tried to do something hinky", pid, comm);
		return _EACCESS;
	}

so the sysadmin becomes aware of the malicious attempt?

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Re: [PATCH] infiniband: remove WARN that is not kernel bug

[Jason Gunthorpe]

On Fri, Nov 18, 2016 at 09:22:42PM -0500, Valdis.Kletnieks@vt.edu wrote:
> On Fri, 18 Nov 2016 12:24:37 +0100, Dmitry Vyukov said:
> > WARNINGs mean kernel bugs.
> > The one in ucma_write() points to user programming error
> > or a malicious attempt. This is not a kernel bug, remove it.
> 
> > -	if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
> > +	if (!ib_safe_file_access(filp))
> >  		return -EACCES;
> 
> In that case, wouldn't this be better?
> 
> 	if (!ib_safe_file_access(filp)) {
> 		printk_once("Process %d (%s) tried to do something hinky", pid, comm);
> 		return _EACCESS;
> 	}
> 
> so the sysadmin becomes aware of the malicious attempt?

Yes please

Jason

Re: [PATCH] infiniband: remove WARN that is not kernel bug

[Dmitry Vyukov]

On Sat, Nov 19, 2016 at 7:57 PM, Jason Gunthorpe
<jgunthorpe@obsidianresearch.com> wrote:
> On Fri, Nov 18, 2016 at 09:22:42PM -0500, Valdis.Kletnieks@vt.edu wrote:
>> On Fri, 18 Nov 2016 12:24:37 +0100, Dmitry Vyukov said:
>> > WARNINGs mean kernel bugs.
>> > The one in ucma_write() points to user programming error
>> > or a malicious attempt. This is not a kernel bug, remove it.
>>
>> > -   if (WARN_ON_ONCE(!ib_safe_file_access(filp)))
>> > +   if (!ib_safe_file_access(filp))
>> >             return -EACCES;
>>
>> In that case, wouldn't this be better?
>>
>>       if (!ib_safe_file_access(filp)) {
>>               printk_once("Process %d (%s) tried to do something hinky", pid, comm);
>>               return _EACCESS;
>>       }
>>
>> so the sysadmin becomes aware of the malicious attempt?
>
> Yes please

Mailed v2