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[PATCH 1/2 v1.1][BZ #14547] Fix CVE-2012-4412


Hi,

Here's an updated patch with some small changes based on some bugs I
found in my patch.  Patch 2/2 will have the test case to verify that
this does not regress.  It runs for 5 minutes and causes a lot of pain
to the build system, so I've kept it as an xtests like Andreas Schwab
suggested.

No regressions in the testsuite (with check and xcheck) as tested on
x86_64 and x86.

Siddhesh

	[BZ #14547]
	* string/strcoll_l.c (coll_seq): New members rule, idx,
	save_idx and back_us.
	(get_next_seq_nocache): New function.
	(do_compare_nocache): New function.
	(STRCOLL): Use get_next_seq_nocache and do_compare_nocache
	when malloc fails.

diff --git a/string/strcoll_l.c b/string/strcoll_l.c
index 50ed84d..eb042ff 100644
--- a/string/strcoll_l.c
+++ b/string/strcoll_l.c
@@ -45,7 +45,7 @@
 typedef struct
 {
   int len;			/* Length of the current sequence.  */
-  int val;			/* Position of the sequence relative to the
+  size_t val;			/* Position of the sequence relative to the
 				   previous non-ignored sequence.  */
   size_t idxnow;		/* Current index in sequences.  */
   size_t idxmax;		/* Maximum index in sequences.  */
@@ -55,6 +55,12 @@ typedef struct
   const USTRING_TYPE *us;	/* The string.  */
   int32_t *idxarr;		/* Array to cache weight indices.  */
   unsigned char *rulearr;	/* Array to cache rules.  */
+  unsigned char rule;		/* Saved rule for the first sequence.  */
+  int32_t idx;			/* Index to weight of the current sequence.  */
+  int32_t save_idx;		/* Save looked up index of a forward
+				   sequence after the last backward
+				   sequence.  */
+  const USTRING_TYPE *back_us;	/* Beginning of the backward sequence.  */
 } coll_seq;
 
 /* Get next sequence.  The weight indices are cached, so we don't need to
@@ -64,7 +70,7 @@ get_next_seq_cached (coll_seq *seq, int nrules, int pass,
 		     const unsigned char *rulesets,
 		     const USTRING_TYPE *weights)
 {
-  int val = seq->val = 0;
+  size_t val = seq->val = 0;
   int len = seq->len;
   size_t backw_stop = seq->backw_stop;
   size_t backw = seq->backw;
@@ -146,7 +152,7 @@ get_next_seq (coll_seq *seq, int nrules, const unsigned char *rulesets,
 	      const USTRING_TYPE *extra, const int32_t *indirect)
 {
 #include WEIGHT_H
-  int val = seq->val = 0;
+  size_t val = seq->val = 0;
   int len = seq->len;
   size_t backw_stop = seq->backw_stop;
   size_t backw = seq->backw;
@@ -162,7 +168,7 @@ get_next_seq (coll_seq *seq, int nrules, const unsigned char *rulesets,
       ++val;
       if (backw_stop != ~0ul)
 	{
-	  /* The is something pushed.  */
+	  /* There is something pushed.  */
 	  if (backw == backw_stop)
 	    {
 	      /* The last pushed character was handled.  Continue
@@ -227,15 +233,199 @@ get_next_seq (coll_seq *seq, int nrules, const unsigned char *rulesets,
   seq->us = us;
 }
 
-/* Compare two sequences.  */
+/* Get next sequence.  Traverse the string as required.  This function does not
+   set or use any index or rule cache.  */
+static void
+get_next_seq_nocache (coll_seq *seq, int nrules, const unsigned char *rulesets,
+		      const USTRING_TYPE *weights, const int32_t *table,
+		      const USTRING_TYPE *extra, const int32_t *indirect,
+		      int pass)
+{
+#include WEIGHT_H
+  size_t val = seq->val = 0;
+  int len = seq->len;
+  size_t backw_stop = seq->backw_stop;
+  size_t backw = seq->backw;
+  size_t idxcnt = seq->idxcnt;
+  size_t idxmax = seq->idxmax;
+  int32_t idx = seq->idx;
+  const USTRING_TYPE *us = seq->us;
+
+  while (len == 0)
+    {
+      ++val;
+      if (backw_stop != ~0ul)
+	{
+	  /* There is something pushed.  */
+	  if (backw == backw_stop)
+	    {
+	      /* The last pushed character was handled.  Continue
+		 with forward characters.  */
+	      if (idxcnt < idxmax)
+		{
+		  idx = seq->save_idx;
+		  backw_stop = ~0ul;
+		}
+	      else
+		{
+		  /* Nothing anymore.  The backward sequence ended with
+		     the last sequence in the string.  Note that len is
+		     still zero.  */
+		  idx = 0;
+		  break;
+	        }
+	    }
+	  else
+	    {
+	      /* XXX Traverse BACKW sequences from the beginning of
+		 BACKW_STOP to get the next sequence.  Is ther a quicker way
+	         to do this?  */
+	      size_t i = backw_stop;
+	      us = seq->back_us;
+	      while (i < backw)
+		{
+		  int32_t tmp = findidx (&us, -1);
+		  idx = tmp & 0xffffff;
+		  i++;
+		}
+	      --backw;
+	      us = seq->us;
+	    }
+	}
+      else
+	{
+	  backw_stop = idxmax;
+	  int32_t prev_idx = idx;
+
+	  while (*us != L('\0'))
+	    {
+	      int32_t tmp = findidx (&us, -1);
+	      unsigned char rule = tmp >> 24;
+	      prev_idx = idx;
+	      idx = tmp & 0xffffff;
+	      idxcnt = idxmax++;
+
+	      /* Save the rule for the first sequence.  */
+	      if (__glibc_unlikely (idxcnt == 0))
+	        seq->rule = rule;
+
+	      if ((rulesets[rule * nrules + pass]
+		   & sort_backward) == 0)
+		/* No more backward characters to push.  */
+		break;
+	      ++idxcnt;
+	    }
+
+	  if (backw_stop >= idxcnt)
+	    {
+	      /* No sequence at all or just one.  */
+	      if (idxcnt == idxmax || backw_stop > idxcnt)
+		/* Note that len is still zero.  */
+		break;
+
+	      backw_stop = ~0ul;
+	    }
+	  else
+	    {
+	      /* We pushed backward sequences.  If the stream ended with the
+		 backward sequence, then we process the last sequence we
+		 found.  Otherwise we process the sequence before the last
+		 one since the last one was a forward sequence.  */
+	      seq->back_us = seq->us;
+	      seq->us = us;
+	      backw = idxcnt;
+	      if (idxmax > idxcnt)
+		{
+		  backw--;
+		  seq->save_idx = idx;
+		  idx = prev_idx;
+		}
+	      if (backw > backw_stop)
+		backw--;
+	    }
+	}
+
+      len = weights[idx++];
+      /* Skip over indices of previous levels.  */
+      for (int i = 0; i < pass; i++)
+	{
+	  idx += len;
+	  len = weights[idx];
+	  idx++;
+	}
+    }
+
+  /* Update the structure.  */
+  seq->val = val;
+  seq->len = len;
+  seq->backw_stop = backw_stop;
+  seq->backw = backw;
+  seq->idxcnt = idxcnt;
+  seq->idxmax = idxmax;
+  seq->us = us;
+  seq->idx = idx;
+}
+
+/* Compare two sequences.  This version does not use the index and rules
+   cache.  */
+static int
+do_compare_nocache (coll_seq *seq1, coll_seq *seq2, int position,
+		    const USTRING_TYPE *weights)
+{
+  int seq1len = seq1->len;
+  int seq2len = seq2->len;
+  size_t val1 = seq1->val;
+  size_t val2 = seq2->val;
+  int idx1 = seq1->idx;
+  int idx2 = seq2->idx;
+  int result = 0;
+
+  /* Test for position if necessary.  */
+  if (position && val1 != val2)
+    {
+      result = val1 > val2 ? 1 : -1;
+      goto out;
+    }
+
+  /* Compare the two sequences.  */
+  do
+    {
+      if (weights[idx1] != weights[idx2])
+	{
+	  /* The sequences differ.  */
+	  result = weights[idx1] - weights[idx2];
+	  goto out;
+	}
+
+      /* Increment the offsets.  */
+      ++idx1;
+      ++idx2;
+
+      --seq1len;
+      --seq2len;
+    }
+  while (seq1len > 0 && seq2len > 0);
+
+  if (position && seq1len != seq2len)
+    result = seq1len - seq2len;
+
+out:
+  seq1->len = seq1len;
+  seq2->len = seq2len;
+  seq1->idx = idx1;
+  seq2->idx = idx2;
+  return result;
+}
+
+/* Compare two sequences using the index cache.  */
 static int
 do_compare (coll_seq *seq1, coll_seq *seq2, int position,
 	    const USTRING_TYPE *weights)
 {
   int seq1len = seq1->len;
   int seq2len = seq2->len;
-  int val1 = seq1->val;
-  int val2 = seq2->val;
+  size_t val1 = seq1->val;
+  size_t val2 = seq2->val;
   int32_t *idx1arr = seq1->idxarr;
   int32_t *idx2arr = seq2->idxarr;
   int idx1now = seq1->idxnow;
@@ -245,7 +435,7 @@ do_compare (coll_seq *seq1, coll_seq *seq2, int position,
   /* Test for position if necessary.  */
   if (position && val1 != val2)
     {
-      result = val1 - val2;
+      result = val1 > val2 ? 1 : -1;
       goto out;
     }
 
@@ -334,57 +524,62 @@ STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l)
   memset (&seq1, 0, sizeof (seq1));
   seq2 = seq1;
 
-  /* We need the elements of the strings as unsigned values since they
-     are used as indices.  */
-  seq1.us = (const USTRING_TYPE *) s1;
-  seq2.us = (const USTRING_TYPE *) s2;
-
   if (! __libc_use_alloca ((s1len + s2len) * (sizeof (int32_t) + 1)))
     {
       seq1.idxarr = (int32_t *) malloc ((s1len + s2len) * (sizeof (int32_t) + 1));
-      seq2.idxarr = &seq1.idxarr[s1len];
-      seq1.rulearr = (unsigned char *) &seq2.idxarr[s2len];
-      seq2.rulearr = &seq1.rulearr[s1len];
-
-      if (seq1.idxarr == NULL)
-	/* No memory.  Well, go with the stack then.
-
-	   XXX Once this implementation is stable we will handle this
-	   differently.  Instead of precomputing the indices we will
-	   do this in time.  This means, though, that this happens for
-	   every pass again.  */
-	goto try_stack;
-      use_malloc = true;
+
+      /* If we failed to allocate memory, we leave everything as NULL so that
+	 we use the nocache version of traversal and comparison functions.  */
+      if (seq1.idxarr != NULL)
+	{
+	  seq2.idxarr = &seq1.idxarr[s1len];
+	  seq1.rulearr = (unsigned char *) &seq2.idxarr[s2len];
+	  seq2.rulearr = &seq1.rulearr[s1len];
+	  use_malloc = true;
+	}
     }
   else
     {
-    try_stack:
       seq1.idxarr = (int32_t *) alloca (s1len * sizeof (int32_t));
       seq2.idxarr = (int32_t *) alloca (s2len * sizeof (int32_t));
       seq1.rulearr = (unsigned char *) alloca (s1len);
       seq2.rulearr = (unsigned char *) alloca (s2len);
     }
 
-  seq1.rulearr[0] = 0;
+  int rule = 0;
 
   /* Cache values in the first pass and if needed, use them in subsequent
      passes.  */
   for (int pass = 0; pass < nrules; ++pass)
     {
       seq1.idxcnt = 0;
+      seq1.idx = 0;
+      seq2.idx = 0;
       seq1.backw_stop = ~0ul;
       seq1.backw = ~0ul;
       seq2.idxcnt = 0;
       seq2.backw_stop = ~0ul;
       seq2.backw = ~0ul;
 
+      /* We need the elements of the strings as unsigned values since they
+	 are used as indices.  */
+      seq1.us = (const USTRING_TYPE *) s1;
+      seq2.us = (const USTRING_TYPE *) s2;
+
       /* We assume that if a rule has defined `position' in one section
 	 this is true for all of them.  */
-      int position = rulesets[seq1.rulearr[0] * nrules + pass] & sort_position;
+      int position = rulesets[rule * nrules + pass] & sort_position;
 
       while (1)
 	{
-	  if (pass == 0)
+	  if (__glibc_unlikely (seq1.idxarr == NULL))
+	    {
+	      get_next_seq_nocache (&seq1, nrules, rulesets, weights, table,
+				    extra, indirect, pass);
+	      get_next_seq_nocache (&seq2, nrules, rulesets, weights, table,
+				    extra, indirect, pass);
+	    }
+	  else if (pass == 0)
 	    {
 	      get_next_seq (&seq1, nrules, rulesets, weights, table, extra,
 			    indirect);
@@ -411,10 +606,18 @@ STRCOLL (const STRING_TYPE *s1, const STRING_TYPE *s2, __locale_t l)
 	      goto free_and_return;
 	    }
 
-	  result = do_compare (&seq1, &seq2, position, weights);
+	  if (__glibc_unlikely (seq1.idxarr == NULL))
+	    result = do_compare_nocache (&seq1, &seq2, position, weights);
+	  else
+	    result = do_compare (&seq1, &seq2, position, weights);
 	  if (result != 0)
 	    goto free_and_return;
 	}
+
+      if (__glibc_likely (seq1.rulearr != NULL))
+	rule = seq1.rulearr[0];
+      else
+	rule = seq1.rule;
     }
 
   /* Free the memory if needed.  */


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