[libbacktrace] Handle alt FORMS without .gnu_debugaltlink

Handle DW_FORM_GNU_strp_alt and DW_FORM_GNU_ref_alt references robustly in
presence of missing .gnu_debugaltlink file.

2019-01-17  Tom de Vries  <tdevries@suse.de>

	* dwarf.c (enum attr_val_encoding): Add ATTR_VAL_NONE.
	(read_attribute): Add altlink parameter.  Handle missing altlink for
	DW_FORM_GNU_strp_alt and DW_FORM_GNU_ref_alt.
	(find_address_ranges, build_address_map, build_dwarf_data): Add and
	handle altlink parameter.
	(read_referenced_name, read_function_entry): Add argument to
	read_attribute call.

From-SVN: r267995

diff --git a/libbacktrace/ChangeLog b/libbacktrace/ChangeLog
index dfb17f5905ef4b74b97a4e5882ccb01fb775cc6d..fb8aebe95c1ae08d579a4476717a0ac62b04b826 100644 (file)
--- a/libbacktrace/ChangeLog
+++ b/libbacktrace/ChangeLog
@@ -1,3 +1,13 @@
+2019-01-17  Tom de Vries  <tdevries@suse.de>
+
+       * dwarf.c (enum attr_val_encoding): Add ATTR_VAL_NONE.
+       (read_attribute): Add altlink parameter.  Handle missing altlink for
+       DW_FORM_GNU_strp_alt and DW_FORM_GNU_ref_alt.
+       (find_address_ranges, build_address_map, build_dwarf_data): Add and
+       handle altlink parameter.
+       (read_referenced_name, read_function_entry): Add argument to
+       read_attribute call.
+
 2019-01-17  Tom de Vries  <tdevries@suse.de>
 
        * dwarf.c (struct dwarf_data): Add altlink field.

diff --git a/libbacktrace/dwarf.c b/libbacktrace/dwarf.c
index 83cdb52ef2615917764d09506dbb47a4b686ee60..4cae5b4f4a3e166e0bbb0a641fb47ed6d1156f0d 100644 (file)
--- a/libbacktrace/dwarf.c
+++ b/libbacktrace/dwarf.c
@@ -129,6 +129,8 @@ struct abbrevs
 
 enum attr_val_encoding
 {
+  /* No attribute value.  */
+  ATTR_VAL_NONE,
   /* An address.  */
   ATTR_VAL_ADDRESS,
   /* A unsigned integer.  */
@@ -700,7 +702,7 @@ static int
 read_attribute (enum dwarf_form form, struct dwarf_buf *buf,
                int is_dwarf64, int version, int addrsize,
                const unsigned char *dwarf_str, size_t dwarf_str_size,
-               struct attr_val *val)
+               struct dwarf_data *altlink, struct attr_val *val)
 {
   /* Avoid warnings about val.u.FIELD may be used uninitialized if
      this function is inlined.  The warnings aren't valid but can
@@ -806,7 +808,7 @@ read_attribute (enum dwarf_form form, struct dwarf_buf *buf,
        form = read_uleb128 (buf);
        return read_attribute ((enum dwarf_form) form, buf, is_dwarf64,
                               version, addrsize, dwarf_str, dwarf_str_size,
-                              val);
+                              altlink, val);
       }
     case DW_FORM_sec_offset:
       val->encoding = ATTR_VAL_REF_SECTION;
@@ -832,12 +834,22 @@ read_attribute (enum dwarf_form form, struct dwarf_buf *buf,
       val->u.uint = read_uleb128 (buf);
       return 1;
     case DW_FORM_GNU_ref_alt:
-      val->encoding = ATTR_VAL_REF_SECTION;
       val->u.uint = read_offset (buf, is_dwarf64);
+      if (altlink == NULL)
+       {
+         val->encoding = ATTR_VAL_NONE;
+         return 1;
+       }
+      val->encoding = ATTR_VAL_REF_SECTION;
       return 1;
     case DW_FORM_GNU_strp_alt:
-      val->encoding = ATTR_VAL_REF_SECTION;
       val->u.uint = read_offset (buf, is_dwarf64);
+      if (altlink == NULL)
+       {
+         val->encoding = ATTR_VAL_NONE;
+         return 1;
+       }
+      val->encoding = ATTR_VAL_REF_SECTION;
       return 1;
     default:
       dwarf_buf_error (buf, "unrecognized DWARF form");
@@ -1275,9 +1287,9 @@ find_address_ranges (struct backtrace_state *state, uintptr_t base_address,
                     const unsigned char *dwarf_str, size_t dwarf_str_size,
                     const unsigned char *dwarf_ranges,
                     size_t dwarf_ranges_size,
-                    int is_bigendian, backtrace_error_callback error_callback,
-                    void *data, struct unit *u,
-                    struct unit_addrs_vector *addrs)
+                    int is_bigendian, struct dwarf_data *altlink,
+                    backtrace_error_callback error_callback, void *data,
+                    struct unit *u, struct unit_addrs_vector *addrs)
 {
   while (unit_buf->left > 0)
     {
@@ -1313,7 +1325,7 @@ find_address_ranges (struct backtrace_state *state, uintptr_t base_address,
 
          if (!read_attribute (abbrev->attrs[i].form, unit_buf,
                               u->is_dwarf64, u->version, u->addrsize,
-                              dwarf_str, dwarf_str_size, &val))
+                              dwarf_str, dwarf_str_size, altlink, &val))
            return 0;
 
          switch (abbrev->attrs[i].name)
@@ -1411,7 +1423,7 @@ find_address_ranges (struct backtrace_state *state, uintptr_t base_address,
          if (!find_address_ranges (state, base_address, unit_buf,
                                    dwarf_str, dwarf_str_size,
                                    dwarf_ranges, dwarf_ranges_size,
-                                   is_bigendian, error_callback, data,
+                                   is_bigendian, altlink, error_callback, data,
                                    u, addrs))
            return 0;
        }
@@ -1430,8 +1442,9 @@ build_address_map (struct backtrace_state *state, uintptr_t base_address,
                   const unsigned char *dwarf_abbrev, size_t dwarf_abbrev_size,
                   const unsigned char *dwarf_ranges, size_t dwarf_ranges_size,
                   const unsigned char *dwarf_str, size_t dwarf_str_size,
-                  int is_bigendian, backtrace_error_callback error_callback,
-                  void *data, struct unit_addrs_vector *addrs)
+                  int is_bigendian, struct dwarf_data *altlink,
+                  backtrace_error_callback error_callback, void *data,
+                  struct unit_addrs_vector *addrs)
 {
   struct dwarf_buf info;
   struct backtrace_vector units;
@@ -1532,7 +1545,7 @@ build_address_map (struct backtrace_state *state, uintptr_t base_address,
       if (!find_address_ranges (state, base_address, &unit_buf,
                                dwarf_str, dwarf_str_size,
                                dwarf_ranges, dwarf_ranges_size,
-                               is_bigendian, error_callback, data,
+                               is_bigendian, altlink, error_callback, data,
                                u, addrs))
        goto fail;
 
@@ -2184,7 +2197,7 @@ read_referenced_name (struct dwarf_data *ddata, struct unit *u,
       if (!read_attribute (abbrev->attrs[i].form, &unit_buf,
                           u->is_dwarf64, u->version, u->addrsize,
                           ddata->dwarf_str, ddata->dwarf_str_size,
-                          &val))
+                          ddata->altlink, &val))
        return NULL;
 
       switch (abbrev->attrs[i].name)
@@ -2396,7 +2409,7 @@ read_function_entry (struct backtrace_state *state, struct dwarf_data *ddata,
          if (!read_attribute (abbrev->attrs[i].form, unit_buf,
                               u->is_dwarf64, u->version, u->addrsize,
                               ddata->dwarf_str, ddata->dwarf_str_size,
-                              &val))
+                              ddata->altlink, &val))
            return 0;
 
          /* The compile unit sets the base address for any address
@@ -3014,7 +3027,8 @@ build_dwarf_data (struct backtrace_state *state,
   if (!build_address_map (state, base_address, dwarf_info, dwarf_info_size,
                          dwarf_abbrev, dwarf_abbrev_size, dwarf_ranges,
                          dwarf_ranges_size, dwarf_str, dwarf_str_size,
-                         is_bigendian, error_callback, data, &addrs_vec))
+                         is_bigendian, altlink, error_callback, data,
+                         &addrs_vec))
     return NULL;
 
   if (!backtrace_vector_release (state, &addrs_vec.vec, error_callback, data))