[binutils-gdb] readelf: handle corrupted chains better

[Michael Frysinger]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=94d15024fe3dff908ab570aaa741b1c834c856d6

commit 94d15024fe3dff908ab570aaa741b1c834c856d6
Author: Mike Frysinger <vapier@gentoo.org>
Date:   Tue Feb 24 01:47:51 2015 -0500

    readelf: handle corrupted chains better
    
    The current chain walker tries to protect itself against loops, by only
    works with loops of length 1: a chain that points to itself.  If you have
    a chain longer than that (3->4->3->4->...), readelf will still hang.
    
    Since we know the max length of the chain, simply abort when we've walked
    more times than that.  The only way that could have happened is if there
    was a loop.

Diff:
---
 binutils/ChangeLog |  7 +++++++
 binutils/readelf.c | 23 +++++++++++++----------
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index a462145..599c82c 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,10 @@
+2015-02-24  Mike Frysinger  <vapier@gentoo.org>
+
+	PR binutils/17531
+	* readelf.c (process_symbol_table): Declare chained.  Increment it
+	in every loop.  Abort when chained is larger than nchains.  Move
+	error check outside of chain loop.
+
 2015-02-24  Dmitry Antipov  <dantipov@nvidia.com>
 
 	* readelf.c (find_symbol_for_address): Use a binary search to
diff --git a/binutils/readelf.c b/binutils/readelf.c
index 7394e76..b3f4733 100644
--- a/binutils/readelf.c
+++ b/binutils/readelf.c
@@ -10783,6 +10783,7 @@ process_symbol_table (FILE * file)
       unsigned long maxlength = 0;
       unsigned long nzero_counts = 0;
       unsigned long nsyms = 0;
+      unsigned long chained;
 
       printf (_("\nHistogram for bucket list length (total of %lu buckets):\n"),
 	      (unsigned long) nbuckets);
@@ -10797,21 +10798,23 @@ process_symbol_table (FILE * file)
       printf (_(" Length  Number     %% of total  Coverage\n"));
       for (hn = 0; hn < nbuckets; ++hn)
 	{
-	  for (si = buckets[hn]; si > 0 && si < nchains && si < nbuckets; si = chains[si])
+	  for (si = buckets[hn], chained = 0;
+	       si > 0 && si < nchains && si < nbuckets && chained <= nchains;
+	       si = chains[si], ++chained)
 	    {
 	      ++nsyms;
 	      if (maxlength < ++lengths[hn])
 		++maxlength;
-
-	      /* PR binutils/17531: A corrupt binary could contain broken
-		 histogram data.  Do not go into an infinite loop trying
-		 to process it.  */
-	      if (chains[si] == si)
-		{
-		  error (_("histogram chain links to itself\n"));
-		  break;
-		}
 	    }
+
+	    /* PR binutils/17531: A corrupt binary could contain broken
+	       histogram data.  Do not go into an infinite loop trying
+	       to process it.  */
+	    if (chained > nchains)
+	      {
+		error (_("histogram chain is corrupt\n"));
+		break;
+	      }
 	}
 
       counts = (unsigned long *) calloc (maxlength + 1, sizeof (*counts));