http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58543
Bug ID: 58543
Summary: Invalid unpoisoning of stack redzones on ARM
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: sanitizer
Assignee: unassigned at gcc dot gnu.org
Reporter: y.gribov at samsung dot com
CC: dodji at gcc dot gnu.org, dvyukov at gcc dot gnu.org,
jakub at gcc dot gnu.org, kcc at gcc dot gnu.org
Created attachment 30902
--> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30902&action=edit
Repro
Gcc seems to generate mismatched prologue/epilogue code to poison/unpoison
stack frame for the attached source code when I compile it with
$ ~/install/gcc-master-arm/bin/arm-v7a15v3r2-linux-gnueabi-gcc bad.i -O0 -S
-fsanitize=address
Prologue seems to poison words at frame_shadow_base + { 0, 4, 8, 12, 16, 24,
28}:
add r4, r3, #536870912
ldr r3, .L3+8
str r3, [r4]
ldr r3, .L3+12
str r3, [r4, #4]
ldr r3, .L3+16
str r3, [r4, #8]
ldr r3, .L3+20
str r3, [r4, #12]
ldr r3, .L3+16
str r3, [r4, #16]
ldr r3, .L3+20
str r3, [r4, #24]
ldr r3, .L3+24
str r3, [r4, #28]
Whereas epilogue poisons frame_shadow_base + { 0, 4, 8, 12, 16, 40, 44}:
add r3, r4, #20
.L1:
mov r2, #0
str r2, [r4]
add r4, r4, #4
cmp r4, r3
bcc .L1
add r3, r4, #24 ; r3 gets invalid value here
mov r2, #0
strb r2, [r3]
add r3, r3, #1
mov r2, #0
strb r2, [r3]
add r3, r3, #1
mov r2, #0
strb r2, [r3]
add r3, r3, #1
mov r2, #0
strb r2, [r3]
add r3, r3, #1
mov r2, #0
strb r2, [r3]
add r3, r3, #1
mov r2, #0
strb r2, [r3]
add r3, r3, #1
mov r2, #0
strb r2, [r3]
add r3, r3, #1
mov r2, #0
strb r2, [r3]
This causes some shadow bytes to remain set after function returns. Those may
trigger incorrect Asan errors later.
-Y
PS: my configuration:
* GCC version: trunk, September 24
* OS: Ubuntu 12.04
* GCC configuration string: ~/gcc/gcc-master/configure
--target=arm-v7a15v3r2-linux-gnueabi
--prefix=/home/ygribov/install/gcc-master-arm --disable-libmudflap
--disable-libssp --disable-nls --enable-long-long --enable-languages=c,c++
--disable-bootstrap --disable-multilib --disable-libstdcxx --disable-libgcc
--disable-libgomp --disable-libatomic --disable-libquadmath
--disable-libstdc++-v3 --disable-libsanitizer --disable-libitm
