gbproxy: Remove nonnull attributes

The compiler also uses this attribute for code elimination. If the
nonnull attribute has been given erroneously for an parameter, that
is later been checked against NULL, this check is removed silently
by the gcc if optimization is enabled. This can lead to hard-to-find
segmentation violation faults.

To be on the safe side, this patch removes all uses of the nonnull
attribute in openbsc.

Compiler:
  - gcc 4.8.2 (Ubuntu 4.8.2-19ubuntu1): no warning, segfault
  - clang 3.4 (3.4-1ubuntu3): no warning, no segfault, asm ok

Example:
  /* foo.c */
  int f(int* p) __attribute((nonnull));
  int f(int *p) {
      if (!p)
          return 0;

      return *p;
  }

  /* main.c */
  int f(int* p) __attribute((nonnull));
  int g () {
      return f(arg);
  }

  int main() {
      return g(NULL);
  }

When these files are compiled into an executable, no warnungs are
issued but it will fail with a segfault when -O2 is used (unless LTO
is active).

Compiler output (gcc -O2):
  int f(int *p) {
    0:  8b 44 24 04             mov    0x4(%esp),%eax
    4:  8b 00                   mov    (%eax),%eax
    6:  c3                      ret
  }

Sponsored-by: On-Waves ehf

1 files changed, 4 insertions, 4 deletions

diff --git a/openbsc/include/openbsc/gprs_gb_parse.h b/openbsc/include/openbsc/gprs_gb_parse.h
index e5ef4ef43..0aa364765 100644
--- a/openbsc/include/openbsc/gprs_gb_parse.h
+++ b/openbsc/include/openbsc/gprs_gb_parse.h
@@ -40,13 +40,13 @@ struct gprs_gb_parse_context {
 };
 
 int gprs_gb_parse_dtap(uint8_t *data, size_t data_len,
-		       struct gprs_gb_parse_context *parse_ctx) __attribute__((nonnull));
+		       struct gprs_gb_parse_context *parse_ctx);
 
 int gprs_gb_parse_llc(uint8_t *llc, size_t llc_len,
-		      struct gprs_gb_parse_context *parse_ctx) __attribute__((nonnull));
+		      struct gprs_gb_parse_context *parse_ctx);
 
 int gprs_gb_parse_bssgp(uint8_t *bssgp, size_t bssgp_len,
-			struct gprs_gb_parse_context *parse_ctx) __attribute__((nonnull));
+			struct gprs_gb_parse_context *parse_ctx);
 
 void gprs_gb_log_parse_context(struct gprs_gb_parse_context *parse_ctx,
-			       const char *default_msg_name) __attribute__((nonnull(1)));
+			       const char *default_msg_name);