kallsyms: fix segfault in prefix_underscores_count()

Commit b478b782e110fdb4135caa3062b6d687e989d994 "kallsyms, tracing: output
more proper symbol name" introduces a "bugfix" that introduces a segfault
in kallsyms in my configurations.

The cause is the introduction of prefix_underscores_count() which attempts
to count underscores, even in symbols that do not have them.  As a result,
it just uselessly runs past the end of the buffer until it crashes:

  CC      init/version.o
  LD      init/built-in.o
  LD      .tmp_vmlinux1
  KSYM    .tmp_kallsyms1.S
/bin/sh: line 1: 16934 Done                    sh-linux-gnu-nm -n .tmp_vmlinux1
     16935 Segmentation fault      | scripts/kallsyms > .tmp_kallsyms1.S
make: *** [.tmp_kallsyms1.S] Error 139

This simplifies the logic and just does a straightforward count.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Paulo Marques <pmarques@grupopie.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>		[2.6.30.x, 2.6.31.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/scripts/kallsyms.c b/scripts/kallsyms.c
index 64343cc084b41f2f9f813742c381717e41ab77ac..86c3896a1e01862b222adeaac4e33bc9b8a01aad 100644 (file)
--- a/scripts/kallsyms.c
+++ b/scripts/kallsyms.c
@@ -585,7 +585,7 @@ static int prefix_underscores_count(const char *str)
 {
        const char *tail = str;
 
-       while (*tail != '_')
+       while (*tail == '_')
                tail++;
 
        return tail - str;