* Re: [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings
@ 2005-12-25 20:08 James Lamanna
2005-12-25 20:35 ` Kees Cook
0 siblings, 1 reply; 6+ messages in thread
From: James Lamanna @ 2005-12-25 20:08 UTC (permalink / raw)
To: kees; +Cc: linux-kernel, trivial
Kees Cook wrote:
> Eliminates compile-time warnings from "r" being uninitialized.
>
What version of gcc are you using?
I get no warnings on 3.4.4:
CC [M] lib/zlib_inflate/infblock.o
CC [M] lib/zlib_inflate/infcodes.o
CC [M] lib/zlib_inflate/inffast.o
CC [M] lib/zlib_inflate/inflate.o
CC [M] lib/zlib_inflate/inflate_sync.o
CC [M] lib/zlib_inflate/inftrees.o
CC [M] lib/zlib_inflate/infutil.o
CC [M] lib/zlib_inflate/inflate_syms.o
LD [M] lib/zlib_inflate/zlib_inflate.o
Building modules, stage 2.
MODPOST
CC lib/zlib_inflate/zlib_inflate.mod.o
LD [M] lib/zlib_inflate/zlib_inflate.ko
agard linux-2.6.15-rc7 # gcc --version
gcc (GCC) 3.4.4 (Gentoo 3.4.4-r1, ssp-3.4.4-1.0, pie-8.7.8)
Looks like a gcc bug that was fixed?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings
2005-12-25 20:08 [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings James Lamanna
@ 2005-12-25 20:35 ` Kees Cook
2005-12-25 20:43 ` Al Viro
0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2005-12-25 20:35 UTC (permalink / raw)
To: James Lamanna; +Cc: linux-kernel, trivial
On Sun, Dec 25, 2005 at 12:08:00PM -0800, James Lamanna wrote:
> What version of gcc are you using?
gcc (GCC) 4.0.3 20051201 (prerelease) (Debian 4.0.2-5)
> Looks like a gcc bug that was fixed?
I guess it's been introduced. ;)
--
Kees Cook @outflux.net
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings
2005-12-25 20:35 ` Kees Cook
@ 2005-12-25 20:43 ` Al Viro
0 siblings, 0 replies; 6+ messages in thread
From: Al Viro @ 2005-12-25 20:43 UTC (permalink / raw)
To: Kees Cook; +Cc: James Lamanna, linux-kernel, trivial
On Sun, Dec 25, 2005 at 12:35:32PM -0800, Kees Cook wrote:
> On Sun, Dec 25, 2005 at 12:08:00PM -0800, James Lamanna wrote:
> > What version of gcc are you using?
>
> gcc (GCC) 4.0.3 20051201 (prerelease) (Debian 4.0.2-5)
>
> > Looks like a gcc bug that was fixed?
>
> I guess it's been introduced. ;)
4.0.x is very bad in that area - it's crying "wolf" a _lot_ and genuine
cases of uninitialized variables being used are drowning in the noise;
compared to 3.x it's a serious regression.
^ permalink raw reply [flat|nested] 6+ messages in thread
* [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings
@ 2005-12-25 18:07 Kees Cook
2005-12-25 18:34 ` Al Viro
0 siblings, 1 reply; 6+ messages in thread
From: Kees Cook @ 2005-12-25 18:07 UTC (permalink / raw)
To: trivial; +Cc: linux-kernel
Eliminates compile-time warnings from "r" being uninitialized.
Signed-of-by: Kees Cook <kees@outflux.net>
---
--- linux-2.6.15-rc7/lib/zlib_inflate/inftrees.c.orig 2005-12-25 09:51:01.000000000 -0800
+++ linux-2.6.15-rc7/lib/zlib_inflate/inftrees.c 2005-12-25 09:46:06.000000000 -0800
@@ -196,6 +196,7 @@ static int huft_build(
u[0] = NULL; /* just to keep compilers happy */
q = NULL; /* ditto */
z = 0; /* ditto */
+ r.word.pad = r.base = 0; /* ditto */
/* go through the bit lengths (k already is bits in shortest code) */
for (; k <= g; k++)
--
Kees Cook @outflux.net
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings
2005-12-25 18:07 Kees Cook
@ 2005-12-25 18:34 ` Al Viro
2005-12-25 20:39 ` Kees Cook
0 siblings, 1 reply; 6+ messages in thread
From: Al Viro @ 2005-12-25 18:34 UTC (permalink / raw)
To: Kees Cook; +Cc: trivial, linux-kernel
On Sun, Dec 25, 2005 at 10:07:58AM -0800, Kees Cook wrote:
> Eliminates compile-time warnings from "r" being uninitialized.
NAK. That sort of patches is only going to hide real problems in the
code where such warnings are _not_ false positives.
Let me put it that way: what bug are you fixing in that patch? Is
there a codepath that would lead to use of r without initialization?
If there is - show it; if there is not - why are you patching kernel
and not gcc?
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings
2005-12-25 18:34 ` Al Viro
@ 2005-12-25 20:39 ` Kees Cook
0 siblings, 0 replies; 6+ messages in thread
From: Kees Cook @ 2005-12-25 20:39 UTC (permalink / raw)
To: Al Viro; +Cc: trivial, linux-kernel
On Sun, Dec 25, 2005 at 06:34:06PM +0000, Al Viro wrote:
> NAK. That sort of patches is only going to hide real problems in the
> code where such warnings are _not_ false positives.
>
> Let me put it that way: what bug are you fixing in that patch? Is
> there a codepath that would lead to use of r without initialization?
> If there is - show it; if there is not - why are you patching kernel
> and not gcc?
Well, good point. My only question would be: why are other
"uninitialized" variables masked in the same way in that code?
Also, perhaps the phrasing in SubmittingPatches should be changed.
Currently (for "trivial" patches) it says:
Warning fixes (cluttering with useless warnings is bad)
Is that warning considered "useful"? Should this hint, instead, read:
Warning fixes (make sure the warning is "real", if not, patch gcc)
:)
--
Kees Cook @outflux.net
^ permalink raw reply [flat|nested] 6+ messages in thread
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2005-12-25 20:08 [PATCH] lib: zlib_inflate "r.base" uninitialized compile warnings James Lamanna
2005-12-25 20:35 ` Kees Cook
2005-12-25 20:43 ` Al Viro
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