diff mbox

Fix x86 strncat optimized implementation for large sizes

Message ID 1483455360-818-1-git-send-email-adhemerval.zanella@linaro.org
State Dropped
Headers

Commit Message

Adhemerval Zanella Jan. 3, 2017, 2:56 p.m. UTC 
  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.

	[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.
---
 ChangeLog                                        | 10 ++++++++++
 string/test-strncat.c                            | 15 +++++++++++++++
 sysdeps/i386/i686/multiarch/strcat-sse2.S        |  2 ++
 sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S |  2 ++
 4 files changed, 29 insertions(+)

Comments

Siddhesh Poyarekar Jan. 3, 2017, 3:05 p.m. UTC | #1 
On Tuesday 03 January 2017 08:26 PM, Adhemerval Zanella wrote:
> 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.
> 
> 	[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.

LGTM.

Siddhesh
diff mbox

Patch

diff --git a/string/test-strncat.c b/string/test-strncat.c
index 55d6cc5..26a6b5b 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 145ae66..6359c73 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 c038043..6a5ab7a 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