On Thu 2018-12-13 12:09:49, Nicholas Mc Guire wrote:
> kzalloc() return should always be checked - notably in example code
> where this may be seen as reference. On failure of allocation
> livepatch_fix1_dummy_alloc() should return NULL.
>
> Signed-off-by: Nicholas Mc Guire <hofrat@xxxxxxxxx>
> ---
>
> Problem was located with an experimental coccinelle script
>
> Patch was compile tested with: x86_64_defconfig + FTRACE=y
> FUNCTION_TRACER=y, EXPERT=y, LATENCYTOP=y, SAMPLES=y, SAMPLE_LIVEPATCH=y
> (with some unrelated sparse warnings on symbols not being static)
>
> Patch is against 4.20-rc6 (localversion-next is next-20181213)
>
> samples/livepatch/livepatch-shadow-fix1.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
> index 49b1355..a0e8f04 100644
> --- a/samples/livepatch/livepatch-shadow-fix1.c
> +++ b/samples/livepatch/livepatch-shadow-fix1.c
> @@ -89,6 +89,9 @@ struct dummy *livepatch_fix1_dummy_alloc(void)
> * pointer to handle resource release.
> */
> leak = kzalloc(sizeof(int), GFP_KERNEL);
> + if (!leak)
> + return NULL;
It should be:
if (!leak) {
kfree(d);
return NULL;
}
Note that The check is not strictly needed in this artificial
example because we never read/write any data there. But I agree
that we should add the check to promote the the right programming
patterns.
Best Regards,
Petr
