Re: [LTP] [PATCH] Fix FILECAPS test hanging for more than 12 hours

["Serge E. Hallyn" <serue@us.ibm.com>]

Quoting Garrett Cooper (yanegomi@gmail.com):
> >                p = index(buf, '.')+1;

Jinkeys!  The intertubes archives insist I wrote that, but I'm finding
it hard to believe.

> > -               if (p==(char *)1) {
> > -                       tst_resm(TFAIL, "got a bad message from print_caps\n");
> > -                       tst_exit();
> > -               }
> > +               if (p==(char *)1)
> > +                       tst_brkm(TFAIL, tst_exit, "got a bad message from print_caps\n");
> 
>     This is a really incorrect way to do things. I think that the
> assumption made was that index(3) would return 0 ('\0') if it fails to
> find '.'. That's incorrect and would cause a segfault on some systems
> (does on FreeBSD at least... don't see why it would pass on Linux):
> 
> $ ~/test_null_inc
> Segmentation fault: 11 (core dumped)
> [garrcoop@bioshock ~]$ cat ~/test_null_inc.c
> #include <stdio.h>
> int
> main(void)
> {
> 	printf("%s\n", (NULL + 1));
> 	return 0;
> }

Well, that's different - you're dereferencing NULL+1, whereas I'm
just checking the the value of the pointer.  

Still what I did is darned ugly, cleanup below.

thanks,
-serge

>     Could you please change this to check and see whether or not index
> returns NULL instead of accessing memory like that?
>     Other than that, patch looks good.

From: Serge E. Hallyn <serue@us.ibm.com>
Date: Wed, 5 May 2010 02:59:05 -0500
Subject: [PATCH 1/1] check for index(3) returning NULL

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
---
 .../kernel/security/filecaps/verify_caps_exec.c    |    5 +++--
 1 files changed, 3 insertions(+), 2 deletions(-)

diff --git a/testcases/kernel/security/filecaps/verify_caps_exec.c b/testcases/kernel/security/filecaps/verify_caps_exec.c
index c3f65a9..605f0f6 100644
--- a/testcases/kernel/security/filecaps/verify_caps_exec.c
+++ b/testcases/kernel/security/filecaps/verify_caps_exec.c
@@ -182,9 +182,10 @@ int fork_drop_and_exec(int keepperms, cap_t expected_caps)
 			tst_resm(TINFO, "got a bad seqno (c=%d, s=%d, seqno=%d)",
 				c, s, seqno);
 		}
-		p = index(buf, '.')+1;
-		if (p==(char *)1)
+		p = index(buf, '.');
+		if (!p)
 			tst_brkm(TFAIL, tst_exit, "got a bad message from print_caps\n");
+		p += 1;
 		actual_caps = cap_from_text(p);
 		if (cap_compare(actual_caps, expected_caps) != 0) {
 			capstxt = cap_to_text(expected_caps, NULL);
-- 
1.6.0.6


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