[binutils-gdb] asan: assert (addr_ranges) <= (start)

[Alan Modra]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=359c74415c2b78bf2b2be3bd3e013d78f298350d

commit 359c74415c2b78bf2b2be3bd3e013d78f298350d
Author: Alan Modra <amodra@gmail.com>
Date:   Wed Nov 3 14:50:18 2021 +1030

    asan: assert (addr_ranges) <= (start)
    
    That assert would be more obvious if it were reported as
    "addr_ranges <= end_ranges".  Fix that by using the obvious variable
    in the final loop.  Stop the assertion by using a signed comparison:
    It's possible for the rounding up of the arange pointer to exceed the
    end of the block when the block size is fuzzed.
    
            * dwarf.c (display_debug_aranges): Use "end_ranges" in loop
            displaying ranges rather that "start".  Simplify rounding up
            to 2*address_size boundary.  Use signed comparison in loop.

Diff:
---
 binutils/dwarf.c | 19 +++++++++----------
 1 file changed, 9 insertions(+), 10 deletions(-)

diff --git a/binutils/dwarf.c b/binutils/dwarf.c
index d42dc64b397..a118c5b794e 100644
--- a/binutils/dwarf.c
+++ b/binutils/dwarf.c
@@ -7192,7 +7192,6 @@ display_debug_aranges (struct dwarf_section *section,
       dwarf_vma address;
       unsigned long sec_off;
       unsigned char address_size;
-      int excess;
       unsigned int offset_size;
       unsigned char *end_ranges;
 
@@ -7277,22 +7276,22 @@ display_debug_aranges (struct dwarf_section *section,
       addr_ranges = hdrptr;
 
       /* Must pad to an alignment boundary that is twice the address size.  */
-      excess = (hdrptr - start) % (2 * address_size);
-      if (excess)
-	addr_ranges += (2 * address_size) - excess;
+      addr_ranges += (2 * address_size - 1
+		      - (hdrptr - start - 1) % (2 * address_size));
 
-      start = end_ranges;
-
-      while (2u * address_size <= (size_t) (start - addr_ranges))
+      while (2 * address_size <= end_ranges - addr_ranges)
 	{
-	  SAFE_BYTE_GET_AND_INC (address, addr_ranges, address_size, start);
-	  SAFE_BYTE_GET_AND_INC (length, addr_ranges, address_size, start);
-
+	  SAFE_BYTE_GET_AND_INC (address, addr_ranges, address_size,
+				 end_ranges);
+	  SAFE_BYTE_GET_AND_INC (length, addr_ranges, address_size,
+				 end_ranges);
 	  printf ("    ");
 	  print_dwarf_vma (address, address_size);
 	  print_dwarf_vma (length, address_size);
 	  putchar ('\n');
 	}
+
+      start = end_ranges;
     }
 
   printf ("\n");