* [PATCH] livepatch: fix size mismatch
@ 2019-01-23 10:31 Nicholas Mc Guire
2019-01-23 14:58 ` Miroslav Benes
0 siblings, 1 reply; 2+ messages in thread
From: Nicholas Mc Guire @ 2019-01-23 10:31 UTC (permalink / raw)
To: Josh Poimboeuf
Cc: Jessica Yu, Jiri Kosina, Miroslav Benes, Petr Mladek,
live-patching, linux-kernel, Nicholas Mc Guire
kzalloc(sizeof(int)) is called for an int object but then
passed into klp_shadow_alloc() using the size of the pointer.
This probably is not a problem as it will fit - but it should
be cleaned (after all this is reference code).
Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
---
Reported by coccicheck
samples/livepatch//livepatch-shadow-fix1.c:97:30-36: ERROR: application of sizeof to pointer
Patch was compile tested with: x86_64_defconfig + FTRACE=y,
FUNCTION_TRACER=y, SAMPLES=y, LIVEPATCH=y SAMPLE_LIVEPATCH=m
Patch is against 5.0-rc3 (localversion-next is next-20190123)
samples/livepatch/livepatch-shadow-fix1.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
index a5a5cac..643ffd5 100644
--- a/samples/livepatch/livepatch-shadow-fix1.c
+++ b/samples/livepatch/livepatch-shadow-fix1.c
@@ -94,7 +94,7 @@ struct dummy *livepatch_fix1_dummy_alloc(void)
return NULL;
}
- klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
+ klp_shadow_alloc(d, SV_LEAK, sizeof(*leak), GFP_KERNEL,
shadow_leak_ctor, leak);
pr_info("%s: dummy @ %p, expires @ %lx\n",
--
2.1.4
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] livepatch: fix size mismatch
2019-01-23 10:31 [PATCH] livepatch: fix size mismatch Nicholas Mc Guire
@ 2019-01-23 14:58 ` Miroslav Benes
0 siblings, 0 replies; 2+ messages in thread
From: Miroslav Benes @ 2019-01-23 14:58 UTC (permalink / raw)
To: Nicholas Mc Guire
Cc: Josh Poimboeuf, Jessica Yu, Jiri Kosina, Petr Mladek,
live-patching, linux-kernel
On Wed, 23 Jan 2019, Nicholas Mc Guire wrote:
> kzalloc(sizeof(int)) is called for an int object but then
> passed into klp_shadow_alloc() using the size of the pointer.
> This probably is not a problem as it will fit - but it should
> be cleaned (after all this is reference code).
>
> Signed-off-by: Nicholas Mc Guire <hofrat@osadl.org>
> ---
>
> Reported by coccicheck
> samples/livepatch//livepatch-shadow-fix1.c:97:30-36: ERROR: application of sizeof to pointer
>
> Patch was compile tested with: x86_64_defconfig + FTRACE=y,
> FUNCTION_TRACER=y, SAMPLES=y, LIVEPATCH=y SAMPLE_LIVEPATCH=m
>
> Patch is against 5.0-rc3 (localversion-next is next-20190123)
>
> samples/livepatch/livepatch-shadow-fix1.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/samples/livepatch/livepatch-shadow-fix1.c b/samples/livepatch/livepatch-shadow-fix1.c
> index a5a5cac..643ffd5 100644
> --- a/samples/livepatch/livepatch-shadow-fix1.c
> +++ b/samples/livepatch/livepatch-shadow-fix1.c
> @@ -94,7 +94,7 @@ struct dummy *livepatch_fix1_dummy_alloc(void)
> return NULL;
> }
>
> - klp_shadow_alloc(d, SV_LEAK, sizeof(leak), GFP_KERNEL,
> + klp_shadow_alloc(d, SV_LEAK, sizeof(*leak), GFP_KERNEL,
> shadow_leak_ctor, leak);
I think it is actually fine. We allocate something sizeof(int), but it is
not important much. The leaked pointer is important. We attach the pointer
as a shadow variable, so we can free it later. Thus, the size of the
pointer is important.
Moreover, you're introducing this with the change:
samples/livepatch/livepatch-shadow-fix1.c:97:38: warning: expression using sizeof(void)
Miroslav
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