GNU C Library master sources branch master updated. glibc-2.24-532-g3daef2c

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- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=3daef2c8ee4df29b9806e3bb2f407417c1222e9a

commit 3daef2c8ee4df29b9806e3bb2f407417c1222e9a
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Thu Dec 15 18:17:09 2016 -0200

    Fix x86_64 memchr for large input sizes
    
    Current optimized memchr for x86_64 does for input arguments pointers
    module 64 in range of [49,63] if there is no searchr char in the rest
    of 64-byte block a pointer addition which might overflow:
    
    * sysdeps/x86_64/memchr.S
    
        77          .p2align 4
        78  L(unaligned_no_match):
        79          add     %rcx, %rdx
    
    Add (uintptr_t)s % 16 to n in %rdx.
    
        80          sub     $16, %rdx
        81          jbe     L(return_null)
    
    This patch fixes by adding a saturated math that sets a maximum pointer
    value if it overflows (UINTPTR_MAX).
    
    Checked on x86_64-linux-gnu and powerpc64-linux-gnu.
    
    	[BZ# 19387]
    	* sysdeps/x86_64/memchr.S (memchr): Avoid overflow in pointer
    	addition.
    	* string/test-memchr.c (do_test): Remove alignment limitation.
    	(test_main): Add test that trigger BZ# 19387.

diff --git a/ChangeLog b/ChangeLog
index f090910..297205c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2016-12-27  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+	[BZ# 19387]
+	* sysdeps/x86_64/memchr.S (memchr): Avoid overflow in pointer
+	addition.
+	* string/test-memchr.c (do_test): Remove alignment limitation.
+	(test_main): Add test that trigger BZ# 19387.
+
 2016-12-26  Nick Alcock  <nick.alcock@oracle.com>
 
 	[BZ #7065]
diff --git a/string/test-memchr.c b/string/test-memchr.c
index 0690cb4..10d696a 100644
--- a/string/test-memchr.c
+++ b/string/test-memchr.c
@@ -76,7 +76,6 @@ do_test (size_t align, size_t pos, size_t len, size_t n, int seek_char)
   size_t i;
   CHAR *result;
 
-  align &= 7;
   if ((align + len) * sizeof (CHAR) >= page_size)
     return;
 
@@ -194,12 +193,12 @@ test_main (void)
       do_test (i, 64, 256, SIZE_MAX, 0);
     }
 
-  for (i = 1; i < 16; ++i)
+  for (i = 1; i < 64; ++i)
     {
-      for (j = 1; j < 16; j++)
+      for (j = 1; j < 64; j++)
         {
-	  do_test (0, 16 - j, 16, SIZE_MAX, 23);
-	  do_test (i, 16 - j, 16, SIZE_MAX, 23);
+	  do_test (0, 64 - j, 64, SIZE_MAX, 23);
+	  do_test (i, 64 - j, 64, SIZE_MAX, 23);
         }
     }
 
diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S
index 132eacb..1e34568 100644
--- a/sysdeps/x86_64/memchr.S
+++ b/sysdeps/x86_64/memchr.S
@@ -76,7 +76,13 @@ L(crosscache):
 
 	.p2align 4
 L(unaligned_no_match):
+        /* Calculate the last acceptable address and check for possible
+           addition overflow by using satured math:
+           rdx = rcx + rdx
+           rdx |= -(rdx < rcx)  */
 	add	%rcx, %rdx
+	sbb	%rax, %rax
+	or	%rax, %rdx
 	sub	$16, %rdx
 	jbe	L(return_null)
 	add	$16, %rdi

-----------------------------------------------------------------------

Summary of changes:
 ChangeLog               |    8 ++++++++
 string/test-memchr.c    |    9 ++++-----
 sysdeps/x86_64/memchr.S |    6 ++++++
 3 files changed, 18 insertions(+), 5 deletions(-)


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