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SubjectRe: [PATCH 2/2] livepatch: check kzalloc return values
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On 12/14/2018 11:56 AM, 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 in
> livepatch_fix1_dummy_alloc() respectively dummy_alloc() previous
> allocation is freed (thanks to Petr Mladek <pmladek@suse.com> for
> catching this) and NULL returned.
>
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> Fixes: 439e7271dc2b ("livepatch: introduce shadow variable API")
> ---
>
> Problem 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
>
> Patch is against 4.20-rc6 (localversion-next is next-20181214)
> on top of 0001-livepatch-fix-non-static-warnings.patch
>
> samples/livepatch/livepatch-shadow-fix1.c | 5 +++++
> samples/livepatch/livepatch-shadow-mod.c | 4 ++++
> 2 files changed, 9 insertions(+)
>
> diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
> index eaab10f..1974eb5 100644
> --- a/samples/livepatch/livepatch-shadow-fix1.c
> +++ b/samples/livepatch/livepatch-shadow-fix1.c
> @@ -89,6 +89,11 @@ static __noclone struct dummy *livepatch_fix1_dummy_alloc(void)
> * pointer to handle resource release.
> */
> leak = kzalloc(sizeof(int), GFP_KERNEL);
> + if (!leak) {
> + kfree(d);
> + return NULL;
> + }
> +
> klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
> shadow_leak_ctor, leak);
>
> diff --git a/samples/livepatch/livepatch-shadow-mod.c b/samples/livepatch/livepatch-shadow-mod.c
> index dc69da0..b4ece36 100644
> --- a/samples/livepatch/livepatch-shadow-mod.c
> +++ b/samples/livepatch/livepatch-shadow-mod.c
> @@ -123,6 +123,10 @@ static __noclone noinline struct dummy *dummy_alloc(void)
>
> /* Oops, forgot to save leak! */
> leak = kzalloc(sizeof(int), GFP_KERNEL);
> + if (!leak) {
> + kfree(d);
> + return NULL;
> + }
>
> pr_info("%s: dummy @ %p, expires @ %lx\n",
> __func__, d, d->jiffies_expire);
>

Patch v2 2/2 looks good, thanks for combining.

Acked-by: Joe Lawrence <joe.lawrence@redhat.com>

-- Joe

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