libdw: Add explicit section index to struct Dwarf_CU

The DIE (attribute) data might come from either the main .debug_info
section or for DWARFv4 from a separate .debug_types section. Or in
case of the fake_loc_cu from the .debug_loc section and in the case
of macros from the .debug_macinfo or .debug_macro section.

We didn't handle the last two "fake" CU cases correctly when sanity
checking offsets in __libdw_read_address and __libdw_read_offset.

Add an explicit sec_idx field to struct Dwarf_CU that is always set
to the actual section that the data came from.

Change-Id: I83260622b55d3778a38cd46427dba158d186c51e
Reviewed-by: Christian Kandeler <[email protected]>

1 files changed, 3 insertions, 2 deletions

diff --git a/libdw/libdw_findcu.c b/libdw/libdw_findcu.c
index 082307b0..4e025e26 100644
--- a/libdw/libdw_findcu.c
+++ b/libdw/libdw_findcu.c
@@ -93,8 +93,8 @@ __libdw_intern_next_unit (Dwarf *dbg, bool debug_types)
     }
 
   /* Invalid or truncated debug section data?  */
-  Elf_Data *data = dbg->sectiondata[debug_types
-				    ? IDX_debug_types : IDX_debug_info];
+  size_t sec_idx = debug_types ? IDX_debug_types : IDX_debug_info;
+  Elf_Data *data = dbg->sectiondata[sec_idx];
   if (unlikely (*offsetp > data->d_size))
     *offsetp = data->d_size;
 
@@ -102,6 +102,7 @@ __libdw_intern_next_unit (Dwarf *dbg, bool debug_types)
   struct Dwarf_CU *newp = libdw_typed_alloc (dbg, struct Dwarf_CU);
 
   newp->dbg = dbg;
+  newp->sec_idx = sec_idx;
   newp->start = oldoff;
   newp->end = *offsetp;
   newp->address_size = address_size;