GNU C Library master sources branch release/2.25/master updated. glibc-2.25-15-gccb4fd7

[azanella at sourceware dot org]

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- Log -----------------------------------------------------------------
http://sourceware.org/git/gitweb.cgi?p=glibc.git;a=commitdiff;h=ccb4fd7a657b0fbc4890c98f4586d58a135fc583

commit ccb4fd7a657b0fbc4890c98f4586d58a135fc583
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date:   Tue Mar 14 14:16:13 2017 -0300

    Fix i686 memchr overflow calculation (BZ#21182)
    
    This patch fixes the regression added by 23d2770 for final address
    overflow calculation.  The subtraction of the considered size (16)
    at line 120 is at wrong place, for sizes less than 16 subsequent
    overflow check will not take in consideration an invalid size (since
    the subtraction will be negative).  Also, the lea instruction also
    does not raise the carry flag (CF) that is used in subsequent jbe
    to check for overflow.
    
    The fix is to follow x86_64 logic from 3daef2c where the overflow
    is first check and a sub instruction is issued.  In case of resulting
    negative size, CF will be set by the sub instruction and a NULL
    result will be returned.  The patch also add similar tests reported
    in bug report.
    
    Checked on i686-linux-gnu and x86_64-linux-gnu.
    
    	* string/test-memchr.c (do_test): Add BZ#21182 checks for address
    	near end of a page.
    	* sysdeps/i386/i686/multiarch/memchr-sse2.S (__memchr): Fix
    	overflow calculation.
    
    Cherry-pick of 3abeeec5f46ff036bd9df60bb096e20314ccd078.

diff --git a/ChangeLog b/ChangeLog
index adebc03..ac19e98 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2017-05-01  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+	[BZ# 21182]
+	* string/test-memchr.c (do_test): Add BZ#21182 checks for address
+	near end of a page.
+	* sysdeps/i386/i686/multiarch/memchr-sse2.S (__memchr): Fix
+	overflow calculation.
+
 2017-04-28  H.J. Lu  <hongjiu.lu@intel.com>
 
 	[BZ #21396]
diff --git a/string/test-memchr.c b/string/test-memchr.c
index d62889f..6431605 100644
--- a/string/test-memchr.c
+++ b/string/test-memchr.c
@@ -208,6 +208,12 @@ test_main (void)
       do_test (0, i, i + 1, i + 1, 0);
     }
 
+  /* BZ#21182 - wrong overflow calculation for i686 implementation
+     with address near end of the page.  */
+  for (i = 2; i < 16; ++i)
+    /* page_size is in fact getpagesize() * 2.  */
+    do_test (page_size / 2 - i, i, i, 1, 0x9B);
+
   do_random_tests ();
   return ret;
 }
diff --git a/sysdeps/i386/i686/multiarch/memchr-sse2.S b/sysdeps/i386/i686/multiarch/memchr-sse2.S
index 910679c..e41f324 100644
--- a/sysdeps/i386/i686/multiarch/memchr-sse2.S
+++ b/sysdeps/i386/i686/multiarch/memchr-sse2.S
@@ -117,7 +117,6 @@ L(crosscache):
 
 # ifndef USE_AS_RAWMEMCHR
 	jnz	L(match_case2_prolog1)
-	lea	-16(%edx), %edx
         /* Calculate the last acceptable address and check for possible
            addition overflow by using satured math:
            edx = ecx + edx
@@ -125,6 +124,7 @@ L(crosscache):
 	add	%ecx, %edx
 	sbb	%eax, %eax
 	or	%eax, %edx
+	sub	$16, %edx
 	jbe	L(return_null)
 	lea	16(%edi), %edi
 # else

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

Summary of changes:
 ChangeLog                                 |    8 ++++++++
 string/test-memchr.c                      |    6 ++++++
 sysdeps/i386/i686/multiarch/memchr-sse2.S |    2 +-
 3 files changed, 15 insertions(+), 1 deletions(-)


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