elf2dmp: check array bounds in pdb_get_file_size

Index in file_size array must be checked against num_files, because the
entries we are looking for may be absent in the PDB.

Fixes: Coverity CID 1521597
Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230930235317.11469-3-viktor@daynix.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

contrib/elf2dmp/pdb.c

@@ -25,6 +25,10 @@
 
 static uint32_t pdb_get_file_size(const struct pdb_reader *r, unsigned idx)
 {
+    if (idx >= r->ds.toc->num_files) {
+        return 0;
+    }
+
     return r->ds.toc->file_size[idx];
 }
 
@@ -159,16 +163,17 @@ static void *pdb_ds_read_file(struct pdb_reader* r, uint32_t file_number)
 
 static int pdb_init_segments(struct pdb_reader *r)
 {
-    char *segs;
     unsigned stream_idx = r->segments;
 
-    segs = pdb_ds_read_file(r, stream_idx);
-    if (!segs) {
+    r->segs = pdb_ds_read_file(r, stream_idx);
+    if (!r->segs) {
         return 1;
     }
 
-    r->segs = segs;
     r->segs_size = pdb_get_file_size(r, stream_idx);
+    if (!r->segs_size) {
+        return 1;
+    }
 
     return 0;
 }