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authorH.J. Lu <hjl.tools@gmail.com>2019-01-21 11:23:59 -0800
committerH.J. Lu <hjl.tools@gmail.com>2019-01-21 11:24:13 -0800
commit97700a34f36721b11a754cf37a1cc40695ece1fd (patch)
tree026802789792449adc9de3532ee8b10685086401 /sysdeps/x86_64/memchr.S
parent6ca53a2453598804a2559a548a08424fca96434a (diff)
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x86-64 memchr/wmemchr: 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 memchr/wmemchr 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/memchr.S: Use RDX_LP for length.  Clear the
	upper 32 bits of RDX register.
	* sysdeps/x86_64/multiarch/memchr-avx2.S: Likewise.
	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memchr and
	tst-size_t-wmemchr.
	* sysdeps/x86_64/x32/test-size_t.h: New file.
	* sysdeps/x86_64/x32/tst-size_t-memchr.c: Likewise.
	* sysdeps/x86_64/x32/tst-size_t-wmemchr.c: Likewise.
Diffstat (limited to 'sysdeps/x86_64/memchr.S')
-rw-r--r--sysdeps/x86_64/memchr.S10
1 files changed, 7 insertions, 3 deletions
diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S
index a6f3ebba22..ec96365217 100644
--- a/sysdeps/x86_64/memchr.S
+++ b/sysdeps/x86_64/memchr.S
@@ -34,12 +34,16 @@ ENTRY(MEMCHR)
 	mov	%edi, %ecx
 
 #ifdef USE_AS_WMEMCHR
-	test	%rdx, %rdx
+	test	%RDX_LP, %RDX_LP
 	jz	L(return_null)
-	shl	$2, %rdx
+	shl	$2, %RDX_LP
 #else
+# ifdef __ILP32__
+	/* Clear the upper 32 bits.  */
+	movl	%edx, %edx
+# endif
 	punpcklbw %xmm1, %xmm1
-	test	%rdx, %rdx
+	test	%RDX_LP, %RDX_LP
 	jz	L(return_null)
 	punpcklbw %xmm1, %xmm1
 #endif