[PATCH] Fix libbacktrace on 32-bit sparc

[David Miller]

I'm getting a SIGBUS on every backtrace libbacktrace generates
on 32-bit sparc builds.  The crashes usually happen in
add_function_range(), where 'p' is not 8-byte aligned.

It seems that the vector code doesn't take care to align the pointers
it returns.  I cribbed the size alignment done in mmap.c's
implementation of backtrace_alloc() to fix this.

Ok to install?

libbacktrace/

2012-10-26  David S. Miller  <da...@davemloft.net>

        * alloc.c (backtrace_vector_grow): Round size up to a multiple
        of 8.
        * mmap.c (backtrace_vector_grow): Likewise.

diff --git a/libbacktrace/alloc.c b/libbacktrace/alloc.c
index 501f386..59072ed 100644
--- a/libbacktrace/alloc.c
+++ b/libbacktrace/alloc.c
@@ -78,6 +78,10 @@ backtrace_vector_grow (struct backtrace_state *state 
ATTRIBUTE_UNUSED,
 {
   void *ret;
 
+  /* Round for alignment; we assume that no type we care about
+     is more than 8 bytes.  */
+  size = (size + 7) & ~ (size_t) 7;
+
   if (size > vec->alc)
     {
       size_t alc;
diff --git a/libbacktrace/mmap.c b/libbacktrace/mmap.c
index e07810d..6e51a0d 100644
--- a/libbacktrace/mmap.c
+++ b/libbacktrace/mmap.c
@@ -175,6 +175,10 @@ backtrace_vector_grow (struct backtrace_state 
*state,size_t size,
 {
   void *ret;
 
+  /* Round for alignment; we assume that no type we care about
+     is more than 8 bytes.  */
+  size = (size + 7) & ~ (size_t) 7;
+
   if (size > vec->alc)
     {
       size_t pagesize;