2023-12-20 15:54:24

by Richard Fitzgerald

[permalink] [raw]
Subject: [PATCH] kunit: Protect string comparisons against NULL

Add NULL checks to KUNIT_BINARY_STR_ASSERTION() so that it will fail
cleanly if either pointer is NULL, instead of causing a NULL pointer
dereference in the strcmp().

A test failure could be that a string is unexpectedly NULL. This could
be trapped by KUNIT_ASSERT_NOT_NULL() but that would terminate the test
at that point. It's preferable that the KUNIT_EXPECT_STR*() macros can
handle NULL pointers as a failure.

Signed-off-by: Richard Fitzgerald <[email protected]>
---
include/kunit/test.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/kunit/test.h b/include/kunit/test.h
index b163b9984b33..c2ce379c329b 100644
--- a/include/kunit/test.h
+++ b/include/kunit/test.h
@@ -758,7 +758,7 @@ do { \
.right_text = #right, \
}; \
\
- if (likely(strcmp(__left, __right) op 0)) \
+ if (likely((__left) && (__right) && (strcmp(__left, __right) op 0))) \
break; \
\
\
--
2.30.2



2023-12-22 08:39:48

by David Gow

[permalink] [raw]
Subject: Re: [PATCH] kunit: Protect string comparisons against NULL

On Wed, 20 Dec 2023 at 23:52, Richard Fitzgerald
<[email protected]> wrote:
>
> Add NULL checks to KUNIT_BINARY_STR_ASSERTION() so that it will fail
> cleanly if either pointer is NULL, instead of causing a NULL pointer
> dereference in the strcmp().
>
> A test failure could be that a string is unexpectedly NULL. This could
> be trapped by KUNIT_ASSERT_NOT_NULL() but that would terminate the test
> at that point. It's preferable that the KUNIT_EXPECT_STR*() macros can
> handle NULL pointers as a failure.
>
> Signed-off-by: Richard Fitzgerald <[email protected]>
> ---

I think this is the right thing to do. There's possibly an argument
that this should succeed if both are NULL, but I prefer it this way.

Reviewed-by: David Gow <[email protected]>

Cheers,
-- David


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2023-12-30 07:18:01

by Muhammad Usama Anjum

[permalink] [raw]
Subject: Re: [PATCH] kunit: Protect string comparisons against NULL

On 12/20/23 8:52 PM, Richard Fitzgerald wrote:
> Add NULL checks to KUNIT_BINARY_STR_ASSERTION() so that it will fail
> cleanly if either pointer is NULL, instead of causing a NULL pointer
> dereference in the strcmp().
>
> A test failure could be that a string is unexpectedly NULL. This could
> be trapped by KUNIT_ASSERT_NOT_NULL() but that would terminate the test
> at that point. It's preferable that the KUNIT_EXPECT_STR*() macros can
> handle NULL pointers as a failure.
>
> Signed-off-by: Richard Fitzgerald <[email protected]>
Reviewed-by: Muhammad Usama Anjum <[email protected]>

> ---
> include/kunit/test.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/kunit/test.h b/include/kunit/test.h
> index b163b9984b33..c2ce379c329b 100644
> --- a/include/kunit/test.h
> +++ b/include/kunit/test.h
> @@ -758,7 +758,7 @@ do { \
> .right_text = #right, \
> }; \
> \
> - if (likely(strcmp(__left, __right) op 0)) \
> + if (likely((__left) && (__right) && (strcmp(__left, __right) op 0))) \
> break; \
> \
> \

--
BR,
Muhammad Usama Anjum

2024-01-04 11:53:05

by Richard Fitzgerald

[permalink] [raw]
Subject: Re: [PATCH] kunit: Protect string comparisons against NULL

On 22/12/23 08:39, David Gow wrote:
> On Wed, 20 Dec 2023 at 23:52, Richard Fitzgerald
> <[email protected]> wrote:
>>
>> Add NULL checks to KUNIT_BINARY_STR_ASSERTION() so that it will fail
>> cleanly if either pointer is NULL, instead of causing a NULL pointer
>> dereference in the strcmp().
>>
>> A test failure could be that a string is unexpectedly NULL. This could
>> be trapped by KUNIT_ASSERT_NOT_NULL() but that would terminate the test
>> at that point. It's preferable that the KUNIT_EXPECT_STR*() macros can
>> handle NULL pointers as a failure.
>>
>> Signed-off-by: Richard Fitzgerald <[email protected]>
>> ---
>
> I think this is the right thing to do. There's possibly an argument
> that this should succeed if both are NULL, but I prefer it this way.
>

Maybe an _OR_NULL() variant of the string test macros would be better to
be explicit that NULL is acceptable.

> Reviewed-by: David Gow <[email protected]>
>
> Cheers,
> -- David