From: Andrew Morton <akpm@osdl.org>
To: Horst von Brand <vonbrand@inf.utfsm.cl>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Ignored return value of __clear_user in fs/binfmt_elf.c?
Date: Wed, 23 Feb 2005 16:54:09 -0800 [thread overview]
Message-ID: <20050223165409.324cc64f.akpm@osdl.org> (raw)
In-Reply-To: <200502231727.j1NHRPGH028335@laptop11.inf.utfsm.cl>
Horst von Brand <vonbrand@inf.utfsm.cl> wrote:
>
> Machine is sparc64, bk of today, gcc-3.4.2-6.fc3 (Aurora Corona). First 2.6
> I try to build here, so it might be something known.
>
> Build fails due to -Werror with:
>
> include/asm/uaccess.h: In function `load_elf_binary':
> arch/sparc64/kernel/../../../fs/binfmt_elf.c:811: warning: ignoring return value of `__clear_user', declared with attribute warn_unused_result
Oh bugger.
> Around line 811 of fs/binfmt_elf.c I see:
>
> /*
> * This bss-zeroing can fail if the ELF file
> * specifies odd protections. So we don't check * the return value
> */
> (void)clear_user((void __user *)elf_bss +
> load_bias, nbyte);
>
> so presumably this discarding is OK here...
>
> I wonder why an explicit (void) cast is not considered "use" by the
> compiler. But then again, explicitly throwing away isn't really "use"...
I'd assumed that it would work. How about this?
--- 25/fs/binfmt_elf.c~binfmt_elf-build-fix Wed Feb 23 16:52:48 2005
+++ 25-akpm/fs/binfmt_elf.c Wed Feb 23 16:53:40 2005
@@ -821,13 +821,14 @@ static int load_elf_binary(struct linux_
nbyte = ELF_MIN_ALIGN - nbyte;
if (nbyte > elf_brk - elf_bss)
nbyte = elf_brk - elf_bss;
- /*
- * This bss-zeroing can fail if the ELF file
- * specifies odd protections. So we don't check
- * the return value
- */
- (void)clear_user((void __user *)elf_bss +
- load_bias, nbyte);
+ if (clear_user((void __user *)elf_bss +
+ load_bias, nbyte)) {
+ /*
+ * This bss-zeroing can fail if the ELF
+ * file specifies odd protections. So
+ * we don't check the return value
+ */
+ }
}
}
_
prev parent reply other threads:[~2005-02-24 0:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-23 17:27 Ignored return value of __clear_user in fs/binfmt_elf.c? Horst von Brand
2005-02-24 0:54 ` Andrew Morton [this message]
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