about summary refs log tree commit diff
path: root/sysdeps
diff options
context:
space:
mode:
authorNoah Goldstein <goldstein.w.n@gmail.com>2022-01-09 16:02:21 -0600
committerNoah Goldstein <goldstein.w.n@gmail.com>2022-01-10 20:31:46 -0600
commitddf0992cf57a93200e0c782e2a94d0733a5a0b87 (patch)
treeb2044b953a5470d020a4324e62f6f20056957a0c /sysdeps
parent347a5b592c91f0230d52a5117fd83e1f75028207 (diff)
downloadglibc-ddf0992cf57a93200e0c782e2a94d0733a5a0b87.tar.gz
glibc-ddf0992cf57a93200e0c782e2a94d0733a5a0b87.tar.xz
glibc-ddf0992cf57a93200e0c782e2a94d0733a5a0b87.zip
x86: Fix __wcsncmp_avx2 in strcmp-avx2.S [BZ# 28755]
Fixes [BZ# 28755] for wcsncmp by redirecting length >= 2^56 to
__wcscmp_avx2. For x86_64 this covers the entire address range so any
length larger could not possibly be used to bound `s1` or `s2`.

test-strcmp, test-strncmp, test-wcscmp, and test-wcsncmp all pass.

Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Diffstat (limited to 'sysdeps')
-rw-r--r--sysdeps/x86_64/multiarch/strcmp-avx2.S10
1 files changed, 10 insertions, 0 deletions
diff --git a/sysdeps/x86_64/multiarch/strcmp-avx2.S b/sysdeps/x86_64/multiarch/strcmp-avx2.S
index a45f9d2749..9c73b5899d 100644
--- a/sysdeps/x86_64/multiarch/strcmp-avx2.S
+++ b/sysdeps/x86_64/multiarch/strcmp-avx2.S
@@ -87,6 +87,16 @@ ENTRY (STRCMP)
 	je	L(char0)
 	jb	L(zero)
 #  ifdef USE_AS_WCSCMP
+#  ifndef __ILP32__
+	movq	%rdx, %rcx
+	/* Check if length could overflow when multiplied by
+	   sizeof(wchar_t). Checking top 8 bits will cover all potential
+	   overflow cases as well as redirect cases where its impossible to
+	   length to bound a valid memory region. In these cases just use
+	   'wcscmp'.  */
+	shrq	$56, %rcx
+	jnz	__wcscmp_avx2
+#  endif
 	/* Convert units: from wide to byte char.  */
 	shl	$2, %RDX_LP
 #  endif