From: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Tue, 3 Jan 2017 14:19:12 +0000 (-0200)
Subject: Fix x86 strncat optimized implementation for large sizes
X-Git-Tag: glibc-2.25~75
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8dad72997af2be0dc72a4bc7dbe82d85c90334fc;p=thirdparty%2Fglibc.git

Fix x86 strncat optimized implementation for large sizes

Similar to BZ#19387, BZ#21014, and BZ#20971, both x86 sse2 strncat
optimized assembly implementations do not handle the size overflow
correctly.

The x86_64 one is in fact an issue with strcpy-sse2-unaligned, but
that is triggered also with strncat optimized implementation.

This patch uses a similar strategy used on 3daef2c8ee4df2, where
saturared math is used for overflow case.

Checked on x86_64-linux-gnu and i686-linux-gnu.  It fixes BZ #19390.

	[BZ #19390]
	* string/test-strncat.c (test_main): Add tests with SIZE_MAX as
	maximum string size.
	* sysdeps/i386/i686/multiarch/strcat-sse2.S (STRCAT): Avoid overflow
	in pointer addition.
	* sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S (STRCPY):
	Likewise.
---

diff --git a/ChangeLog b/ChangeLog
index 8af3a199519..1bb6eaa5367 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2017-01-03  Adhemerval Zanella  <adhemerval.zanella@linaro.org>
+
+	[BZ #19390]
+	* string/test-strncat.c (test_main): Add tests with SIZE_MAX as
+	maximum string size.
+	* sysdeps/i386/i686/multiarch/strcat-sse2.S (STRCAT): Avoid overflow
+	in pointer addition.
+	* sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S (STRCPY):
+	Likewise.
+
 2017-01-03  Joseph Myers  <joseph@codesourcery.com>
 
 	* elf/Makefile ($(objpfx)tst-ldconfig-X.out): Correct arguments
diff --git a/string/test-strncat.c b/string/test-strncat.c
index 55d6cc57628..26a6b5b91df 100644
--- a/string/test-strncat.c
+++ b/string/test-strncat.c
@@ -284,12 +284,23 @@ test_main (void)
       do_test (0, 0, 8, 8, n, SMALL_CHAR);
       do_test (0, 8, 8, 8, n, SMALL_CHAR);
 
+      do_test (0, 2, 2, 2, SIZE_MAX, SMALL_CHAR);
+      do_test (0, 0, 4, 4, SIZE_MAX, SMALL_CHAR);
+      do_test (4, 0, 4, 4, SIZE_MAX, BIG_CHAR);
+      do_test (0, 0, 8, 8, SIZE_MAX, SMALL_CHAR);
+      do_test (0, 8, 8, 8, SIZE_MAX, SMALL_CHAR);
+
       for (i = 1; i < 8; ++i)
 	{
 	  do_test (0, 0, 8 << i, 8 << i, n, SMALL_CHAR);
 	  do_test (8 - i, 2 * i, 8 << i, 8 << i, n, SMALL_CHAR);
 	  do_test (0, 0, 8 << i, 2 << i, n, SMALL_CHAR);
 	  do_test (8 - i, 2 * i, 8 << i, 2 << i, n, SMALL_CHAR);
+
+	  do_test (0, 0, 8 << i, 8 << i, SIZE_MAX, SMALL_CHAR);
+	  do_test (8 - i, 2 * i, 8 << i, 8 << i, SIZE_MAX, SMALL_CHAR);
+	  do_test (0, 0, 8 << i, 2 << i, SIZE_MAX, SMALL_CHAR);
+	  do_test (8 - i, 2 * i, 8 << i, 2 << i, SIZE_MAX, SMALL_CHAR);
 	}
 
       for (i = 1; i < 8; ++i)
@@ -297,6 +308,10 @@ test_main (void)
 	  do_test (i, 2 * i, 8 << i, 1, n, SMALL_CHAR);
 	  do_test (2 * i, i, 8 << i, 1, n, BIG_CHAR);
 	  do_test (i, i, 8 << i, 10, n, SMALL_CHAR);
+
+	  do_test (i, 2 * i, 8 << i, 1, SIZE_MAX, SMALL_CHAR);
+	  do_test (2 * i, i, 8 << i, 1, SIZE_MAX, BIG_CHAR);
+	  do_test (i, i, 8 << i, 10, SIZE_MAX, SMALL_CHAR);
 	}
     }
 
diff --git a/sysdeps/i386/i686/multiarch/strcat-sse2.S b/sysdeps/i386/i686/multiarch/strcat-sse2.S
index 145ae66894c..6359c7330c2 100644
--- a/sysdeps/i386/i686/multiarch/strcat-sse2.S
+++ b/sysdeps/i386/i686/multiarch/strcat-sse2.S
@@ -227,6 +227,8 @@ L(StartStrcpyPart):
 	pxor	%xmm0, %xmm0
 # ifdef USE_AS_STRNCAT
 	add	%ecx, %ebx
+	sbb	%edx, %edx
+	or	%edx, %ebx
 # endif
 	sub	%ecx, %eax
 	jmp	L(Unalign16Both)
diff --git a/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S b/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S
index c038043693b..6a5ab7ab26c 100644
--- a/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S
+++ b/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S
@@ -99,6 +99,8 @@ L(Unalign16Both):
 	sub	%rcx, %rdi
 # ifdef USE_AS_STRNCPY
 	add	%rcx, %r8
+	sbb	%rcx, %rcx
+	or	%rcx, %r8
 # endif
 	mov	$16, %rcx
 	movdqa	(%rsi, %rcx), %xmm1