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[PATCH] Don't write beyond destination in __mempcpy_avx512_no_vzeroupper (bug 23196)
- From: Andreas Schwab <schwab at suse dot de>
- To: libc-alpha at sourceware dot org
- Date: Tue, 22 May 2018 12:06:14 +0200
- Subject: [PATCH] Don't write beyond destination in __mempcpy_avx512_no_vzeroupper (bug 23196)
[BZ #23196]
CVE-2018-11237
* sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S
(L(preloop_large)): Save initial destination pointer in %r11 and
use it instead of %rax after the loop.
* string/test-mempcpy.c (MIN_PAGE_SIZE): Define.
---
string/test-mempcpy.c | 1 +
sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S | 5 +++--
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/string/test-mempcpy.c b/string/test-mempcpy.c
index c08fba895e..d98ecdd2d9 100644
--- a/string/test-mempcpy.c
+++ b/string/test-mempcpy.c
@@ -18,6 +18,7 @@
<http://www.gnu.org/licenses/>. */
#define MEMCPY_RESULT(dst, len) (dst) + (len)
+#define MIN_PAGE_SIZE 131072
#define TEST_MAIN
#define TEST_NAME "mempcpy"
#include "test-string.h"
diff --git a/sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S b/sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S
index 23c0f7a9ed..effc3ac2de 100644
--- a/sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S
+++ b/sysdeps/x86_64/multiarch/memmove-avx512-no-vzeroupper.S
@@ -336,6 +336,7 @@ L(preloop_large):
vmovups (%rsi), %zmm4
vmovups 0x40(%rsi), %zmm5
+ mov %rdi, %r11
/* Align destination for access with non-temporal stores in the loop. */
mov %rdi, %r8
and $-0x80, %rdi
@@ -366,8 +367,8 @@ L(gobble_256bytes_nt_loop):
cmp $256, %rdx
ja L(gobble_256bytes_nt_loop)
sfence
- vmovups %zmm4, (%rax)
- vmovups %zmm5, 0x40(%rax)
+ vmovups %zmm4, (%r11)
+ vmovups %zmm5, 0x40(%r11)
jmp L(check)
L(preloop_large_bkw):
--
2.17.0
--
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."