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authorH.J. Lu <hjl.tools@gmail.com>2019-01-21 11:33:52 -0800
committerH.J. Lu <hjl.tools@gmail.com>2019-01-21 11:34:04 -0800
commitee915088a0231cd421054dbd8abab7aadf331153 (patch)
treebda23563b2fe03f78a95219922c8fecf6a86f9df /sysdeps/x86_64/multiarch
parent82d0b4a4d76db554eb6757acb790fcea30b19965 (diff)
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x86-64 strncmp family: Properly handle the length parameter [BZ# 24097]
On x32, the size_t parameter may be passed in the lower 32 bits of a
64-bit register with the non-zero upper 32 bits.  The string/memory
functions written in assembly can only use the lower 32 bits of a
64-bit register as length or must clear the upper 32 bits before using
the full 64-bit register for length.

This pach fixes the strncmp family for x32.  Tested on x86-64 and x32.
On x86-64, libc.so is the same with and withou the fix.

	[BZ# 24097]
	CVE-2019-6488
	* sysdeps/x86_64/multiarch/strcmp-avx2.S: Use RDX_LP for length.
	* sysdeps/x86_64/multiarch/strcmp-sse42.S: Likewise.
	* sysdeps/x86_64/strcmp.S: Likewise.
	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-strncasecmp,
	tst-size_t-strncmp and tst-size_t-wcsncmp.
	* sysdeps/x86_64/x32/tst-size_t-strncasecmp.c: New file.
	* sysdeps/x86_64/x32/tst-size_t-strncmp.c: Likewise.
	* sysdeps/x86_64/x32/tst-size_t-wcsncmp.c: Likewise.
Diffstat (limited to 'sysdeps/x86_64/multiarch')
-rw-r--r--sysdeps/x86_64/multiarch/strcmp-avx2.S6
-rw-r--r--sysdeps/x86_64/multiarch/strcmp-sse42.S6
2 files changed, 6 insertions, 6 deletions
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index 0c27f90d29..b32a5e3528 100644
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -79,15 +79,15 @@
 ENTRY (STRCMP)
 # ifdef USE_AS_STRNCMP
 	/* Check for simple cases (0 or 1) in offset.  */
-	cmp	$1, %rdx
+	cmp	$1, %RDX_LP
 	je	L(char0)
 	jb	L(zero)
 #  ifdef USE_AS_WCSCMP
 	/* Convert units: from wide to byte char.  */
-	shl	$2, %rdx
+	shl	$2, %RDX_LP
 #  endif
 	/* Register %r11 tracks the maximum offset.  */
-	movq	%rdx, %r11
+	mov	%RDX_LP, %R11_LP
 # endif
 	movl	%edi, %eax
 	xorl	%edx, %edx
diff --git a/sysdeps/x86_64/multiarch/strcmp-sse42.S b/sysdeps/x86_64/multiarch/strcmp-sse42.S
index 2f4b34a03f..73bbe5c9e1 100644
--- a/sysdeps/x86_64/multiarch/strcmp-sse42.S
+++ b/sysdeps/x86_64/multiarch/strcmp-sse42.S
@@ -156,11 +156,11 @@ STRCMP_SSE42:
 #endif
 
 #if defined USE_AS_STRNCMP || defined USE_AS_STRNCASECMP_L
-	test	%rdx, %rdx
+	test	%RDX_LP, %RDX_LP
 	je	LABEL(strcmp_exitz)
-	cmp	$1, %rdx
+	cmp	$1, %RDX_LP
 	je	LABEL(Byte0)
-	mov	%rdx, %r11
+	mov	%RDX_LP, %R11_LP
 #endif
 	mov	%esi, %ecx
 	mov	%edi, %eax