libbacktrace: don't crash if ELF file has no sections

ianlancetaylor · ianlancetaylor · commit 7206f5bd0610 · 2020-05-09T20:36:19.000-07:00
Patch from Roland McGrath. Fixes #41
diff --git a/elf.c b/elf.c
@@ -2781,6 +2781,9 @@ elf_add (struct backtrace_state *state, const char *filename, int descriptor,
       backtrace_release_view (state, &shdr_view, error_callback, data);
     }
 
+  if (shnum == 0 || shstrndx == 0)
+    goto fail;
+
   /* To translate PC to file/line when using DWARF, we need to find
      the .debug_info and .debug_line sections.  */
 

Original file line number	Diff line number	Diff line change
`@@ -2781,6 +2781,9 @@ elf_add (struct backtrace_state state, const char filename, int descriptor,`
`2781`	`2781`	`backtrace_release_view (state, &shdr_view, error_callback, data);`
`2782`	`2782`	`}`
`2783`	`2783`
	`2784`	`+ if (shnum == 0 \|\| shstrndx == 0)`
	`2785`	`+ goto fail;`
	`2786`	`+`
`2784`	`2787`	`/* To translate PC to file/line when using DWARF, we need to find`
`2785`	`2788`	`the .debug_info and .debug_line sections. */`
`2786`	`2789`