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authorTulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>2016-12-28 11:38:56 -0200
committerTulio Magno Quites Machado Filho <tuliom@linux.vnet.ibm.com>2016-12-28 11:44:31 -0200
commit5e628dd118807981bdd880731e6fdf019f64a245 (patch)
treeab1efb6529f5b0c7ee03ab5e2f412e8d212f4717
parent9314d3545e6641063b490918e2e8716556ba20db (diff)
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powerpc: Fix powerpc32/power7 memchr for large input sizes
The same error fixed in commit b224637928e9fc04e3cef3e10d02ccf042d01584
happens in the 32-bit implementation of memchr for power7.

This patch adopts the same solution, with a minimal change: it
implements a saturated addition where overflows sets the maximum pointer
size to UINTPTR_MAX.
-rw-r--r--ChangeLog5
-rw-r--r--sysdeps/powerpc/powerpc32/power7/memchr.S11
2 files changed, 15 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index d9b2c98156..1ad68675c2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2016-12-28  Tulio Magno Quites Machado Filho  <tuliom@linux.vnet.ibm.com>
+
+	* sysdeps/powerpc/powerpc32/power7/memchr.S (__memchr): Avoid an
+	overflow in pointer addition.
+
 2016-12-28  Rajalakshmi Srinivasaraghavan  <raji@linux.vnet.ibm.com>
 
 	* sysdeps/powerpc/powerpc64/multiarch/Makefile
diff --git a/sysdeps/powerpc/powerpc32/power7/memchr.S b/sysdeps/powerpc/powerpc32/power7/memchr.S
index 318168b4cf..5ce2bb0bad 100644
--- a/sysdeps/powerpc/powerpc32/power7/memchr.S
+++ b/sysdeps/powerpc/powerpc32/power7/memchr.S
@@ -26,7 +26,16 @@ ENTRY (__memchr)
 	dcbt	0,r3
 	clrrwi  r8,r3,2
 	insrwi	r4,r4,8,16    /* Replicate byte to word.  */
-	add	r7,r3,r5      /* Calculate the last acceptable address.  */
+
+	/* Calculate the last acceptable address and check for possible
+	   addition overflow by using satured math:
+	   r7 = r3 + r5
+	   r7 |= -(r7 < x)  */
+	add     r7,r3,r5
+	subfc   r6,r3,r7
+	subfe   r9,r9,r9
+	or      r7,r7,r9
+
 	insrwi	r4,r4,16,0
 	cmplwi	r5,16
 	li	r9, -1