From: Miroslav Benes <mbenes@suse.cz>
To: Nicholas Mc Guire <hofrat@osadl.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Jessica Yu <jeyu@kernel.org>, Jiri Kosina <jikos@kernel.org>,
Petr Mladek <pmladek@suse.com>,
live-patching@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] livepatch: fix size mismatch
Date: Wed, 23 Jan 2019 15:58:21 +0100 (CET) [thread overview]
Message-ID: <alpine.LSU.2.21.1901231555270.31908@pobox.suse.cz> (raw)
In-Reply-To: <1548239476-21110-1-git-send-email-hofrat@osadl.org>
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
prev parent reply other threads:[~2019-01-23 14:58 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-23 10:31 [PATCH] livepatch: fix size mismatch Nicholas Mc Guire
2019-01-23 14:58 ` Miroslav Benes [this message]
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