[PATCH] dynamic debug: line queries failing due to uninitialized local variable

[PATCH] dynamic debug: line queries failing due to uninitialized local variable

[jbaron]

Settings of the form, 'line x module y +p', can fail arbitrarily due to an
uninitialized local variable. With this patch results are consistent, as
expected.

Signed-off-by: Jason Baron <jbaron@akamai.com>
---
 lib/dynamic_debug.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c
index 99fec3a..c37aeac 100644
--- a/lib/dynamic_debug.c
+++ b/lib/dynamic_debug.c
@@ -309,7 +309,7 @@ static int ddebug_parse_query(char *words[], int nwords,
 			struct ddebug_query *query, const char *modname)
 {
 	unsigned int i;
-	int rc;
+	int rc = 0;
 
 	/* check we have an even number of words */
 	if (nwords % 2 != 0) {
-- 
1.8.2

Re: [PATCH] dynamic debug: line queries failing due to uninitialized local variable

[Greg KH]

On Tue, Aug 27, 2013 at 04:50:03PM +0000, jbaron@akamai.com wrote:
> Settings of the form, 'line x module y +p', can fail arbitrarily due to an
> uninitialized local variable. With this patch results are consistent, as
> expected.
> 
> Signed-off-by: Jason Baron <jbaron@akamai.com>
> ---
>  lib/dynamic_debug.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

How far back should this patch go for older kernels?  Is this a bug that
people are hitting today and causing problems, or is it only a 3.11-rc
issue?

thanks,

greg k-h

Re: [PATCH] dynamic debug: line queries failing due to uninitialized local variable

[Jason Baron]

On 08/27/2013 01:41 PM, Greg KH wrote:
> On Tue, Aug 27, 2013 at 04:50:03PM +0000, jbaron@akamai.com wrote:
>> Settings of the form, 'line x module y +p', can fail arbitrarily due to an
>> uninitialized local variable. With this patch results are consistent, as
>> expected.
>>
>> Signed-off-by: Jason Baron <jbaron@akamai.com>
>> ---
>>  lib/dynamic_debug.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
> How far back should this patch go for older kernels?  Is this a bug that
> people are hitting today and causing problems, or is it only a 3.11-rc
> issue?
>
> thanks,
>
> greg k-h

Looks like this was introduced in >= 3.3. So its been there for quite a
while. Its a bit of a corner case, since it requires, 'line' to be
specified before anything else. It depends on on how you order your query.

I found the bug via code inspection - no bug reports that I'm aware of.
So I wouldn't think this is an urgent fix.

Thanks,

-Jason