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glibc/SOURCES/glibc-RHEL-15696-24.patch

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From 645a158978f9520e74074e8c14047503be4db0f0 Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n@gmail.com>
Date: Wed, 9 Jun 2021 16:25:32 -0400
Subject: [PATCH] x86: Fix overflow bug with wmemchr-sse2 and wmemchr-avx2 [BZ
#27974]
Content-type: text/plain; charset=UTF-8
This commit fixes the bug mentioned in the previous commit.
The previous implementations of wmemchr in these files relied
on n * sizeof(wchar_t) which was not guranteed by the standard.
The new overflow tests added in the previous commit now
pass (As well as all the other tests).
Signed-off-by: Noah Goldstein <goldstein.w.n@gmail.com>
Reviewed-by: H.J. Lu <hjl.tools@gmail.com>
---
sysdeps/x86_64/memchr.S | 77 +++++++++++++++++++-------
sysdeps/x86_64/multiarch/memchr-avx2.S | 58 +++++++++++++------
2 files changed, 98 insertions(+), 37 deletions(-)
diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S
index cb320257..24f9a0c5 100644
--- a/sysdeps/x86_64/memchr.S
+++ b/sysdeps/x86_64/memchr.S
@@ -21,9 +21,11 @@
#ifdef USE_AS_WMEMCHR
# define MEMCHR wmemchr
# define PCMPEQ pcmpeqd
+# define CHAR_PER_VEC 4
#else
# define MEMCHR memchr
# define PCMPEQ pcmpeqb
+# define CHAR_PER_VEC 16
#endif
/* fast SSE2 version with using pmaxub and 64 byte loop */
@@ -33,15 +35,14 @@ ENTRY(MEMCHR)
movd %esi, %xmm1
mov %edi, %ecx
+#ifdef __ILP32__
+ /* Clear the upper 32 bits. */
+ movl %edx, %edx
+#endif
#ifdef USE_AS_WMEMCHR
test %RDX_LP, %RDX_LP
jz L(return_null)
- shl $2, %RDX_LP
#else
-# ifdef __ILP32__
- /* Clear the upper 32 bits. */
- movl %edx, %edx
-# endif
punpcklbw %xmm1, %xmm1
test %RDX_LP, %RDX_LP
jz L(return_null)
@@ -60,13 +61,16 @@ ENTRY(MEMCHR)
test %eax, %eax
jnz L(matches_1)
- sub $16, %rdx
+ sub $CHAR_PER_VEC, %rdx
jbe L(return_null)
add $16, %rdi
and $15, %ecx
and $-16, %rdi
+#ifdef USE_AS_WMEMCHR
+ shr $2, %ecx
+#endif
add %rcx, %rdx
- sub $64, %rdx
+ sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
jmp L(loop_prolog)
@@ -77,16 +81,21 @@ L(crosscache):
movdqa (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
-/* Check if there is a match. */
+ /* Check if there is a match. */
pmovmskb %xmm0, %eax
-/* Remove the leading bytes. */
+ /* Remove the leading bytes. */
sar %cl, %eax
test %eax, %eax
je L(unaligned_no_match)
-/* Check which byte is a match. */
+ /* Check which byte is a match. */
bsf %eax, %eax
-
+#ifdef USE_AS_WMEMCHR
+ mov %eax, %esi
+ shr $2, %esi
+ sub %rsi, %rdx
+#else
sub %rax, %rdx
+#endif
jbe L(return_null)
add %rdi, %rax
add %rcx, %rax
@@ -94,15 +103,18 @@ L(crosscache):
.p2align 4
L(unaligned_no_match):
- /* "rcx" is less than 16. Calculate "rdx + rcx - 16" by using
+ /* "rcx" is less than 16. Calculate "rdx + rcx - 16" by using
"rdx - (16 - rcx)" instead of "(rdx + rcx) - 16" to void
possible addition overflow. */
neg %rcx
add $16, %rcx
+#ifdef USE_AS_WMEMCHR
+ shr $2, %ecx
+#endif
sub %rcx, %rdx
jbe L(return_null)
add $16, %rdi
- sub $64, %rdx
+ sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
.p2align 4
@@ -135,7 +147,7 @@ L(loop_prolog):
test $0x3f, %rdi
jz L(align64_loop)
- sub $64, %rdx
+ sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
movdqa (%rdi), %xmm0
@@ -167,11 +179,14 @@ L(loop_prolog):
mov %rdi, %rcx
and $-64, %rdi
and $63, %ecx
+#ifdef USE_AS_WMEMCHR
+ shr $2, %ecx
+#endif
add %rcx, %rdx
.p2align 4
L(align64_loop):
- sub $64, %rdx
+ sub $(CHAR_PER_VEC * 4), %rdx
jbe L(exit_loop)
movdqa (%rdi), %xmm0
movdqa 16(%rdi), %xmm2
@@ -218,7 +233,7 @@ L(align64_loop):
.p2align 4
L(exit_loop):
- add $32, %edx
+ add $(CHAR_PER_VEC * 2), %edx
jle L(exit_loop_32)
movdqa (%rdi), %xmm0
@@ -238,7 +253,7 @@ L(exit_loop):
pmovmskb %xmm3, %eax
test %eax, %eax
jnz L(matches32_1)
- sub $16, %edx
+ sub $CHAR_PER_VEC, %edx
jle L(return_null)
PCMPEQ 48(%rdi), %xmm1
@@ -250,13 +265,13 @@ L(exit_loop):
.p2align 4
L(exit_loop_32):
- add $32, %edx
+ add $(CHAR_PER_VEC * 2), %edx
movdqa (%rdi), %xmm0
PCMPEQ %xmm1, %xmm0
pmovmskb %xmm0, %eax
test %eax, %eax
jnz L(matches_1)
- sub $16, %edx
+ sub $CHAR_PER_VEC, %edx
jbe L(return_null)
PCMPEQ 16(%rdi), %xmm1
@@ -293,7 +308,13 @@ L(matches32):
.p2align 4
L(matches_1):
bsf %eax, %eax
+#ifdef USE_AS_WMEMCHR
+ mov %eax, %esi
+ shr $2, %esi
+ sub %rsi, %rdx
+#else
sub %rax, %rdx
+#endif
jbe L(return_null)
add %rdi, %rax
ret
@@ -301,7 +322,13 @@ L(matches_1):
.p2align 4
L(matches16_1):
bsf %eax, %eax
+#ifdef USE_AS_WMEMCHR
+ mov %eax, %esi
+ shr $2, %esi
+ sub %rsi, %rdx
+#else
sub %rax, %rdx
+#endif
jbe L(return_null)
lea 16(%rdi, %rax), %rax
ret
@@ -309,7 +336,13 @@ L(matches16_1):
.p2align 4
L(matches32_1):
bsf %eax, %eax
+#ifdef USE_AS_WMEMCHR
+ mov %eax, %esi
+ shr $2, %esi
+ sub %rsi, %rdx
+#else
sub %rax, %rdx
+#endif
jbe L(return_null)
lea 32(%rdi, %rax), %rax
ret
@@ -317,7 +350,13 @@ L(matches32_1):
.p2align 4
L(matches48_1):
bsf %eax, %eax
+#ifdef USE_AS_WMEMCHR
+ mov %eax, %esi
+ shr $2, %esi
+ sub %rsi, %rdx
+#else
sub %rax, %rdx
+#endif
jbe L(return_null)
lea 48(%rdi, %rax), %rax
ret
diff --git a/sysdeps/x86_64/multiarch/memchr-avx2.S b/sysdeps/x86_64/multiarch/memchr-avx2.S
index b377f22e..16027abb 100644
--- a/sysdeps/x86_64/multiarch/memchr-avx2.S
+++ b/sysdeps/x86_64/multiarch/memchr-avx2.S
@@ -54,21 +54,19 @@
# define VEC_SIZE 32
# define PAGE_SIZE 4096
+# define CHAR_PER_VEC (VEC_SIZE / CHAR_SIZE)
.section SECTION(.text),"ax",@progbits
ENTRY (MEMCHR)
# ifndef USE_AS_RAWMEMCHR
/* Check for zero length. */
- test %RDX_LP, %RDX_LP
- jz L(null)
-# endif
-# ifdef USE_AS_WMEMCHR
- shl $2, %RDX_LP
-# else
# ifdef __ILP32__
- /* Clear the upper 32 bits. */
- movl %edx, %edx
+ /* Clear upper bits. */
+ and %RDX_LP, %RDX_LP
+# else
+ test %RDX_LP, %RDX_LP
# endif
+ jz L(null)
# endif
/* Broadcast CHAR to YMMMATCH. */
vmovd %esi, %xmm0
@@ -84,7 +82,7 @@ ENTRY (MEMCHR)
vpmovmskb %ymm1, %eax
# ifndef USE_AS_RAWMEMCHR
/* If length < CHAR_PER_VEC handle special. */
- cmpq $VEC_SIZE, %rdx
+ cmpq $CHAR_PER_VEC, %rdx
jbe L(first_vec_x0)
# endif
testl %eax, %eax
@@ -98,6 +96,10 @@ ENTRY (MEMCHR)
L(first_vec_x0):
/* Check if first match was before length. */
tzcntl %eax, %eax
+# ifdef USE_AS_WMEMCHR
+ /* NB: Multiply length by 4 to get byte count. */
+ sall $2, %edx
+# endif
xorl %ecx, %ecx
cmpl %eax, %edx
leaq (%rdi, %rax), %rax
@@ -110,12 +112,12 @@ L(null):
# endif
.p2align 4
L(cross_page_boundary):
- /* Save pointer before aligning as its original value is necessary
- for computer return address if byte is found or adjusting length
- if it is not and this is memchr. */
+ /* Save pointer before aligning as its original value is
+ necessary for computer return address if byte is found or
+ adjusting length if it is not and this is memchr. */
movq %rdi, %rcx
- /* Align data to VEC_SIZE - 1. ALGN_PTR_REG is rcx for memchr and
- rdi for rawmemchr. */
+ /* Align data to VEC_SIZE - 1. ALGN_PTR_REG is rcx for memchr
+ and rdi for rawmemchr. */
orq $(VEC_SIZE - 1), %ALGN_PTR_REG
VPCMPEQ -(VEC_SIZE - 1)(%ALGN_PTR_REG), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
@@ -124,6 +126,10 @@ L(cross_page_boundary):
match). */
leaq 1(%ALGN_PTR_REG), %rsi
subq %RRAW_PTR_REG, %rsi
+# ifdef USE_AS_WMEMCHR
+ /* NB: Divide bytes by 4 to get wchar_t count. */
+ shrl $2, %esi
+# endif
# endif
/* Remove the leading bytes. */
sarxl %ERAW_PTR_REG, %eax, %eax
@@ -181,6 +187,10 @@ L(cross_page_continue):
orq $(VEC_SIZE - 1), %rdi
/* esi is for adjusting length to see if near the end. */
leal (VEC_SIZE * 4 + 1)(%rdi, %rcx), %esi
+# ifdef USE_AS_WMEMCHR
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
+ sarl $2, %esi
+# endif
# else
orq $(VEC_SIZE - 1), %rdi
L(cross_page_continue):
@@ -213,7 +223,7 @@ L(cross_page_continue):
# ifndef USE_AS_RAWMEMCHR
/* Check if at last VEC_SIZE * 4 length. */
- subq $(VEC_SIZE * 4), %rdx
+ subq $(CHAR_PER_VEC * 4), %rdx
jbe L(last_4x_vec_or_less_cmpeq)
/* Align data to VEC_SIZE * 4 - 1 for the loop and readjust
length. */
@@ -221,6 +231,10 @@ L(cross_page_continue):
movl %edi, %ecx
orq $(VEC_SIZE * 4 - 1), %rdi
andl $(VEC_SIZE * 4 - 1), %ecx
+# ifdef USE_AS_WMEMCHR
+ /* NB: Divide bytes by 4 to get the wchar_t count. */
+ sarl $2, %ecx
+# endif
addq %rcx, %rdx
# else
/* Align data to VEC_SIZE * 4 - 1 for loop. */
@@ -250,15 +264,19 @@ L(loop_4x_vec):
subq $-(VEC_SIZE * 4), %rdi
- subq $(VEC_SIZE * 4), %rdx
+ subq $(CHAR_PER_VEC * 4), %rdx
ja L(loop_4x_vec)
- /* Fall through into less than 4 remaining vectors of length case.
- */
+ /* Fall through into less than 4 remaining vectors of length
+ case. */
VPCMPEQ (VEC_SIZE * 0 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
.p2align 4
L(last_4x_vec_or_less):
+# ifdef USE_AS_WMEMCHR
+ /* NB: Multiply length by 4 to get byte count. */
+ sall $2, %edx
+# endif
/* Check if first VEC contained match. */
testl %eax, %eax
jnz L(first_vec_x1_check)
@@ -355,6 +373,10 @@ L(last_vec_x2_return):
L(last_4x_vec_or_less_cmpeq):
VPCMPEQ (VEC_SIZE * 4 + 1)(%rdi), %ymm0, %ymm1
vpmovmskb %ymm1, %eax
+# ifdef USE_AS_WMEMCHR
+ /* NB: Multiply length by 4 to get byte count. */
+ sall $2, %edx
+# endif
subq $-(VEC_SIZE * 4), %rdi
/* Check first VEC regardless. */
testl %eax, %eax
--
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