[llvm-bugs] [Bug 39919] New: store happening to wrongly loaded address with thumb2
via llvm-bugs
llvm-bugs at lists.llvm.org
Fri Dec 7 12:10:58 PST 2018
https://bugs.llvm.org/show_bug.cgi?id=39919
Bug ID: 39919
Summary: store happening to wrongly loaded address with thumb2
Product: clang
Version: 7.0
Hardware: PC
OS: Linux
Status: NEW
Severity: normal
Priority: P
Component: LLVM Codegen
Assignee: unassignedclangbugs at nondot.org
Reporter: raj.khem at gmail.com
CC: llvm-bugs at lists.llvm.org, neeilans at live.com,
richard-llvm at metafoo.co.uk
Created attachment 21205
--> https://bugs.llvm.org/attachment.cgi?id=21205&action=edit
testcase
This issue pops up when compiling busybox for arm using thumb2 ISA. Getty
applet segfaults.
Program received signal SIGSEGV, Segmentation fault.
getty_main (argc=<optimized out>, argv=0x7efffd58) at loginutils/getty.c:561
warning: Source file is more recent than executable.
561 G.eol = '\r';
This is also present in the attached reproducer
clang -target armv7l-linux-gnueabihf -S -Os -mthumb getty.c
=====================================================
.code 16 @ @getty_main
.thumb_func
getty_main:
.fnstart
@ %bb.0:
.save {r4, r5, r6, r7, lr}
push {r4, r5, r6, r7, lr}
.setfp r7, sp, #12
add r7, sp, #12
.save {r11}
str r11, [sp, #-4]!
.pad #16
sub sp, #16
mov.w r0, #260
mov r6, r1
bl xzalloc <--------------------------- allocate ptr_to_globals
struct (return address of mem in r0)
ldr r2, .LCPI0_0
ldr r3, .LCPI0_1
.LPC0_0:
add r2, pc
ldr r5, .LCPI0_2
ldr r1, .LCPI0_3
.LPC0_1:
add r3, pc
ldr r4, [r2] <--------------------------- loads the address of
ptr_to_globals struct
.LPC0_2:
add r5, pc
str r0, [r2] <-------------------------- Stores the address
returned from xzalloc()
.LPC0_3:
add r1, pc
@APP
@NO_APP
str r3, [r0, #20]
add.w r2, r4, #20
str r5, [r0, #4]
movs r0, #13
strb.w r0, [r4, #68] <------------- Stores '\r' to globals+68 which is
location of ptr_to_globals.eol
adds r0, r4, #4
add.w r3, r4, #8
strd r2, r0, [sp]
add.w r2, r4, #16
mov r0, r6
str r4, [sp, #8]
bl getopt32
add sp, #16
ldr r11, [sp], #4
pop {r4, r5, r6, r7, pc}
.p2align 2
===============================================
As can be seen above, it has loaded address of ptr_to_globals into r4 before
return of xzalloc() in r0 is stored into it.
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