linux-kernel - Re: [PATCH] sdhci: 'scratch' may be used uninitialized

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <f488382f0810051553t32a24972ma7baa92605f43772@mail.gmail.com>
Date:	Sun, 5 Oct 2008 15:53:28 -0700
From:	"Steven Noonan" <steven@...inklabs.net>
To:	"Adrian Bunk" <bunk@...nel.org>
Cc:	linux-kernel@...r.kernel.org, mingo@...e.hu, drzeus@...eus.cx
Subject: Re: [PATCH] sdhci: 'scratch' may be used uninitialized

On Sun, Oct 5, 2008 at 7:28 AM, Adrian Bunk <bunk@...nel.org> wrote:
> On Wed, Oct 01, 2008 at 01:50:25AM -0700, Steven Noonan wrote:
>> The variable 'scratch' is always initialized before it's used. The
>> conditional which is responsible for initialization of 'scratch' will
>> always evaluate 'true' when the first loop iteration occurs, and thus,
>> it's properly initialized. GCC doesn't see this, of course, so using
>> the uninitialized_var() macro seems to work for silencing this case.
>>
>> Signed-off-by: Steven Noonan <steven@...inklabs.net>
>> ---
>>  drivers/mmc/host/sdhci.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index e3a8133..6257677 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -177,7 +177,7 @@ static void sdhci_read_block_pio(struct sdhci_host *host)
>>  {
>>       unsigned long flags;
>>       size_t blksize, len, chunk;
>> -     u32 scratch;
>> +     u32 uninitialized_var(scratch);
>>...
>
> With which gcc version?
>
> I'm not getting this warning with gcc 4.3, and IMHO it doesn't make
> sense to clutter the source code with such workarounds for older gcc
> versions (we officially support 6 years old compilers, and warning-free
> compilations with all of them are not reasonably possible).
>
> cu
> Adrian

I've seen it on GCC 4.1 and 4.2. Since lots of distributions still
haven't marked GCC >4.1 stable, it makes sense to me to kill warnings
for GCC 4.1 and above. I don't know of any current distribution
releases using less than GCC 4.1 at the moment.

- Steven
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/