libdwfl: Don't assume auxv or r_debug data is properly aligned in link_map.

core file data isn't guaranteed to be alligned properly. Use
read_(4|8)ubyte_unaligned_noncvt to read values, types and addresses.

Signed-off-by: Mark Wielaard <mjw@redhat.com>

2 files changed, 22 insertions, 10 deletions

diff --git a/libdwfl/ChangeLog b/libdwfl/ChangeLog
index ffb34c03..f4e7484b 100644
--- a/libdwfl/ChangeLog
+++ b/libdwfl/ChangeLog
@@ -1,5 +1,12 @@
 2015-05-30  Mark Wielaard  <mjw@redhat.com>
 
+	* link_map.c (check32): Use read_4ubyte_unaligned_noncvt to read
+	type and value.
+	(read_addrs): Use read_(4|8)ubyte_unaligned_noncvt or to read
+	adresses.
+
+2015-05-30  Mark Wielaard  <mjw@redhat.com>
+
 	* find-debuginfo.c (dwfl_standard_find_debuginfo): Check file_name is
 	not NULL before calling canonicalize_file_name.
 
diff --git a/libdwfl/link_map.c b/libdwfl/link_map.c
index a5a69687..030c6002 100644
--- a/libdwfl/link_map.c
+++ b/libdwfl/link_map.c
@@ -58,8 +58,7 @@ auxv_format_probe (const void *auxv, size_t size,
   inline bool check64 (size_t i)
   {
     /* The AUXV pointer might not even be naturally aligned for 64-bit
-       data, because note payloads in a core file are not aligned.
-       But we assume the data is 32-bit aligned.  */
+       data, because note payloads in a core file are not aligned.  */
 
     uint64_t type = read_8ubyte_unaligned_noncvt (&u->a64[i].a_type);
     uint64_t val = read_8ubyte_unaligned_noncvt (&u->a64[i].a_un.a_val);
@@ -83,15 +82,21 @@ auxv_format_probe (const void *auxv, size_t size,
 
   inline bool check32 (size_t i)
   {
-    if (u->a32[i].a_type == BE32 (PROBE_TYPE)
-	&& u->a32[i].a_un.a_val == BE32 (PROBE_VAL32))
+    /* The AUXV pointer might not even be naturally aligned for 32-bit
+       data, because note payloads in a core file are not aligned.  */
+
+    uint32_t type = read_4ubyte_unaligned_noncvt (&u->a32[i].a_type);
+    uint32_t val = read_4ubyte_unaligned_noncvt (&u->a32[i].a_un.a_val);
+
+    if (type == BE32 (PROBE_TYPE)
+	&& val == BE32 (PROBE_VAL32))
       {
 	*elfdata = ELFDATA2MSB;
 	return true;
       }
 
-    if (u->a32[i].a_type == LE32 (PROBE_TYPE)
-	&& u->a32[i].a_un.a_val == LE32 (PROBE_VAL32))
+    if (type == LE32 (PROBE_TYPE)
+	&& val == LE32 (PROBE_VAL32))
       {
 	*elfdata = ELFDATA2LSB;
 	return true;
@@ -285,19 +290,19 @@ report_r_debug (uint_fast8_t elfclass, uint_fast8_t elfdata,
       {
 	if (elfdata == ELFDATA2MSB)
 	  for (size_t i = 0; i < n; ++i)
-	    addrs[i] = BE32 (in->a32[i]);
+	    addrs[i] = BE32 (read_4ubyte_unaligned_noncvt (&in->a32[i]));
 	else
 	  for (size_t i = 0; i < n; ++i)
-	    addrs[i] = LE32 (in->a32[i]);
+	    addrs[i] = LE32 (read_4ubyte_unaligned_noncvt (&in->a32[i]));
       }
     else
       {
 	if (elfdata == ELFDATA2MSB)
 	  for (size_t i = 0; i < n; ++i)
-	    addrs[i] = BE64 (in->a64[i]);
+	    addrs[i] = BE64 (read_8ubyte_unaligned_noncvt (&in->a64[i]));
 	else
 	  for (size_t i = 0; i < n; ++i)
-	    addrs[i] = LE64 (in->a64[i]);
+	    addrs[i] = LE64 (read_8ubyte_unaligned_noncvt (&in->a64[i]));
       }
 
     return false;