On Thu, 16 Sep 2021, Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx> wrote:
> On 15/09/2021 20:23, Tim Gardner wrote:
>> In capture_vma() Coverity complains of a possible buffer overrun. Even
>> though this is a static function where all call sites can be checked,
>> limiting the copy length could save some future grief.
>>
>> CID 93300 (#1 of 1): Copy into fixed size buffer (STRING_OVERFLOW)
>> 4. fixed_size_dest: You might overrun the 16-character fixed-size string c->name
>> by copying name without checking the length.
>> 5. parameter_as_source: Note: This defect has an elevated risk because the
>> source argument is a parameter of the current function.
>> 1326 strcpy(c->name, name);
>>
>> Fix any possible overflows by using strncpy(). Zero fill the name buffer to
>> guarantee ASCII string NULL termination.
>>
>> Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
>> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
>> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>> Cc: David Airlie <airlied@xxxxxxxx>
>> Cc: Daniel Vetter <daniel@xxxxxxxx>
>> Cc: intel-gfx@xxxxxxxxxxxxxxxxxxxxx
>> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> Signed-off-by: Tim Gardner <tim.gardner@xxxxxxxxxxxxx>
>> ---
>> drivers/gpu/drm/i915/i915_gpu_error.c | 7 ++++---
>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
>> index 9cf6ac575de1..154df174e2d7 100644
>> --- a/drivers/gpu/drm/i915/i915_gpu_error.c
>> +++ b/drivers/gpu/drm/i915/i915_gpu_error.c
>> @@ -1297,10 +1297,11 @@ static bool record_context(struct i915_gem_context_coredump *e,
>> return simulated;
>> }
>>
>> +#define VMA_NAME_LEN 16
>> struct intel_engine_capture_vma {
>> struct intel_engine_capture_vma *next;
>> struct i915_vma *vma;
>> - char name[16];
>> + char name[VMA_NAME_LEN];
>> };
>>
>> static struct intel_engine_capture_vma *
>> @@ -1314,7 +1315,7 @@ capture_vma(struct intel_engine_capture_vma *next,
>> if (!vma)
>> return next;
>>
>> - c = kmalloc(sizeof(*c), gfp);
>> + c = kzalloc(sizeof(*c), gfp);
>> if (!c)
>> return next;
>>
>> @@ -1323,7 +1324,7 @@ capture_vma(struct intel_engine_capture_vma *next,
>> return next;
>> }
>>
>> - strcpy(c->name, name);
>> + strncpy(c->name, name, VMA_NAME_LEN-1);
>
> GCC is supposed to catch any problems here as you say in the commit message.
>
> But to fix I suggest a single line change to strlcpy(c->name, name,
> sizeof(c->name)) which always null terminates as bonus.
strscpy() is preferred over both strncpy() and strlcpy(). :)
BR,
Jani.
>
> Probably same in i915_vma_coredump_create() which with strncpy would
> have a theoretical chance of attempting to copy over a
> non-null-terminated string.
>
> Regards,
>
> Tvrtko
>
>> c->vma = vma; /* reference held while active */
>>
>> c->next = next;
>>
--
Jani Nikula, Intel Open Source Graphics Center
