Re: [bug, bisected, -chrisl] Segfault at evaluate.c:341

[Hannes Eder <hannes@hanneseder.net>]

On Thu, Mar 19, 2009 at 3:46 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Thu, Mar 19, 2009 at 02:49:21PM +0100, Hannes Eder wrote:
>> running sparse (from Christopher's tree) on linux-2.6/kernel/cred.c
>> (as of next-20090318, problem may appeared earlier, I have not tried
>> yet) causes a segfault at evaluate.c:341:
>>
>>         if (type->type == SYM_NODE)
>>                 type = type->ctype.base_type;
>>         if (type->type == SYM_TYPEOF) {        <======== SEGFAULT (type == NULL)
>>                 type = evaluate_expression(type->initializer);
>>                 if (type->type == SYM_NODE)
>>                         type = type->ctype.base_type;
>>         }
>>
>> the complete command line:
>>
>> sparse -D__linux__ -Dlinux -D__STDC__ -Dunix -D__unix__ -Wbitwise
>> -Wno-return-void -D__x86_64__ -m64 -nostdinc -isystem
>> /usr/lib/gcc/x86_64-redhat-linux/4.3.2/include
>> -Wp,-MD,kernel/.cred.o.d -nostdinc -isystem
>> /usr/lib/gcc/x86_64-redhat-linux/4.3.2/include -Iinclude
>> -I/home/hannes/linux-2.6/arch/x86/include -include
>> include/linux/autoconf.h -D__KERNEL__ -Wall -Wundef
>> -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing -fno-common
>> -Werror-implicit-function-declaration -Os -m64 -mtune=generic
>> -mno-red-zone -mcmodel=kernel -funit-at-a-time
>> -maccumulate-outgoing-args -fstack-protector -fstack-protector-all
>> -DCONFIG_AS_CFI=1 -DCONFIG_AS_CFI_SIGNAL_FRAME=1 -pipe
>> -Wno-sign-compare -fno-asynchronous-unwind-tables -mno-sse -mno-mmx
>> -mno-sse2 -mno-3dnow -fno-omit-frame-pointer
>> -fno-optimize-sibling-calls -g -pg -Wdeclaration-after-statement
>> -Wno-pointer-sign -D"KBUILD_STR(s)=#s"
>> -D"KBUILD_BASENAME=KBUILD_STR(cred)"
>> -D"KBUILD_MODNAME=KBUILD_STR(cred)" -D"DEBUG_HASH=36"
>> -D"DEBUG_HASH2=28" kernel/cred.c
>>
>>
>> using "git bisect" i narrowed to problem down to:
>>
>> [db31fd91f8231110ce8d8d48ce402f8cad068e44] Fix handling of ident-less
>> declarations
>>
>> Does that help? Should I provide any further information?
>
> Preprocessed input would help (note that knowing the kernel tree in
> question is not enough - .config affects what comes out of preprocessing,
> after all).
>
> Just slap -E in command line above and dump the output someplace public...

I use sparse with -E <rest of the options> and gcc -E -P <rest of the
options> to produce the files
kernel-cred-c.prep.sparse and kernel-cred-c.prep.gcc, which can be found at

http://hanneseder.net/sparse/kernel-cred-c.prep.tar.gz

$ sparse kernel-cred-c.prep.gcc

produces some warnings as usual.

$ sparse kernel-cred-c.prep.sparse

produces some warnings, a boatload of errors, and then segfaults.

hth,
-Hannes
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