Hi,
On Tue, Oct 05, 2021 at 05:32:16PM +0200, Jan-Benedict Glaw wrote:
> I'm running automated test compiles on Binutils, GCC, Linux, NetBSD
> and, since a few days ago, elfutils.
>
> Building/running the tests, I noticed this little warning:
>
> [make 2021-10-01 12:18:15] elflint.c: In function 'check_sections':
> [make 2021-10-01 12:18:15] elflint.c:4105:48: error: null pointer dereference
> [-Werror=null-dereference]
> [make 2021-10-01 12:18:15] 4105 | idx <
> databits->d_size && ! bad;
> [make 2021-10-01 12:18:15] |
> ~~~~~~~~^~~~~~~~
> [make 2021-10-01 12:18:18] cc1: all warnings being treated as errors
> [make 2021-10-01 12:18:18] make[2]: *** [Makefile:799: elflint.o] Error 1
> [make 2021-10-01 12:18:18] make[1]: *** [Makefile:532: all-recursive] Error 1
> [make 2021-10-01 12:18:18] make: *** [Makefile:448: all] Error 2
>
>
> As it is tested beforehand that we should not run into this, this
> patch should fix the warning:
>
>
> diff --git a/src/elflint.c b/src/elflint.c
> index 1ce75684..ef7725ce 100644
> --- a/src/elflint.c
> +++ b/src/elflint.c
> @@ -4102,7 +4102,7 @@ section [%2zu] '%s' has type NOBITS but is read from
> the file in segment of prog
> bad = (databits == NULL
> || databits->d_size != shdr->sh_size);
> for (size_t idx = 0;
> - idx < databits->d_size && ! bad;
> + ! bad && idx < databits->d_size;
> idx++)
> bad = ((char *) databits->d_buf)[idx] != 0;
>
Thanks, that warning and the fix look correct.
I committed the attached fix.
Cheers,
Mark
>From 3d9f12883d0c131bd4ab6045e1f60d3fe6d150ea Mon Sep 17 00:00:00 2001
From: Mark Wielaard <m...@klomp.org>
Date: Wed, 6 Oct 2021 23:37:42 +0200
Subject: [PATCH] elflint.c: Don't dereference databits if bad
elflint.c: In function 'check_sections':
elflint.c:4105:48: error: null pointer dereference [-Werror=null-dereference]
4105 | idx < databits->d_size && ! bad;
| ~~~~~~~~^~~~~~~~
Fix this by testing for ! bad first.
Reported-by: Jan-Benedict Glaw <jbg...@lug-owl.de>
Signed-off-by: Mark Wielaard <m...@klomp.org>
---
src/ChangeLog | 4 ++++
src/elflint.c | 2 +-
2 files changed, 5 insertions(+), 1 deletion(-)
diff --git a/src/ChangeLog b/src/ChangeLog
index 87b3dd46..316bcb6d 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,7 @@
+2021-10-06 Mark Wielaard <m...@klomp.org>
+
+ * elflint.c (check_sections): Don't dereference databits if bad.
+
2021-09-09 Dmitry V. Levin <l...@altlinux.org>
* findtextrel.c: Include "libeu.h".
diff --git a/src/elflint.c b/src/elflint.c
index 1ce75684..ef7725ce 100644
--- a/src/elflint.c
+++ b/src/elflint.c
@@ -4102,7 +4102,7 @@ section [%2zu] '%s' has type NOBITS but is read from the file in segment of prog
bad = (databits == NULL
|| databits->d_size != shdr->sh_size);
for (size_t idx = 0;
- idx < databits->d_size && ! bad;
+ ! bad && idx < databits->d_size;
idx++)
bad = ((char *) databits->d_buf)[idx] != 0;
--
2.32.0
