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authorH.J. Lu <hjl.tools@gmail.com>2019-01-21 11:36:36 -0800
committerH.J. Lu <hjl.tools@gmail.com>2019-01-21 11:36:47 -0800
commit5165de69c0908e28a380cbd4bb054e55ea4abc95 (patch)
tree6be5f660262a283870db3ca16d7f07210859b58f /sysdeps/x86_64/multiarch
parentc7c54f65b080affb87a1513dee449c8ad6143c8b (diff)
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x86-64 strnlen/wcsnlen: 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 strnlen/wcsnlen 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/strlen-avx2.S: Use RSI_LP for length.
	Clear the upper 32 bits of RSI register.
	* sysdeps/x86_64/strlen.S: Use RSI_LP for length.
	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-strnlen
	and tst-size_t-wcsnlen.
	* sysdeps/x86_64/x32/tst-size_t-strnlen.c: New file.
	* sysdeps/x86_64/x32/tst-size_t-wcsnlen.c: Likewise.
Diffstat (limited to 'sysdeps/x86_64/multiarch')
-rw-r--r--sysdeps/x86_64/multiarch/strlen-avx2.S9
1 files changed, 6 insertions, 3 deletions
diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S
index aa0ade503f..3e7f14a846 100644
--- a/sysdeps/x86_64/multiarch/strlen-avx2.S
+++ b/sysdeps/x86_64/multiarch/strlen-avx2.S
@@ -42,12 +42,15 @@
 ENTRY (STRLEN)
 # ifdef USE_AS_STRNLEN
 	/* Check for zero length.  */
-	testq	%rsi, %rsi
+	test	%RSI_LP, %RSI_LP
 	jz	L(zero)
 #  ifdef USE_AS_WCSLEN
-	shl	$2, %rsi
+	shl	$2, %RSI_LP
+#  elif defined __ILP32__
+	/* Clear the upper 32 bits.  */
+	movl	%esi, %esi
 #  endif
-	movq	%rsi, %r8
+	mov	%RSI_LP, %R8_LP
 # endif
 	movl	%edi, %ecx
 	movq	%rdi, %rdx