Out-of-bounds read in 6g (cmd/gc/lex.c:502) #935
Description
by robert.swiecki:
What steps will reproduce the problem?
1. Run '6g SIGSEGV.PC.0x4434de.CODE.2.ADDR.0x7ffff7b2959e.INSTR.movzx_eax,_word_[rax].go'
What is the expected output?
*.6 file or error message
What do you see instead?
Crash (SIGSEGV(
What is your $GOOS? $GOARCH?
linux/amd64
Which revision are you using? (hg identify)
38ac4f394e2f+ tip
Please provide any additional information below.
$ gdb /usr/local/google/src/go/6g
(gdb) r SIGSEGV.PC.0x4434de.CODE.2.ADDR.0x7ffff7b2959e.INSTR.movzx_eax,_word_[rax].go
Program received signal SIGSEGV, Segmentation fault.
0x00000000004434de in _yylex () at /usr/local/google/src/go/src/cmd/gc/lex.c:502
502 if(isspace(c)) {
(gdb) bt
#0 0x00000000004434de in _yylex () at /usr/local/google/src/go/src/cmd/gc/lex.c:502
#1 0x00000000004447e3 in yylex () at /usr/local/google/src/go/src/cmd/gc/lex.c:1174
#2 0x000000000043cfd3 in yyparse () at y.tab.c:2179
#3 0x000000000044284b in p9main (argc=1, argv=0x7fffffffe630) at
/usr/local/google/src/go/src/cmd/gc/lex.c:175
#4 0x000000000044bab4 in main (argc=2, argv=0x7fffffffe628) at
/usr/local/google/src/go/src/lib9/main.c:35
(gdb) x/i $pc
=> 0x4434de <_yylex+61>: movzx eax,WORD PTR [rax]
(gdb) p $rax
0x7ffff7b2959e: Cannot access memory at address 0x7ffff7b2959e
(gdb) info proc
process 12699
(gdb) shell cat /proc/12699/maps
00400000-0046d000 r-xp 00000000 08:06 2730103
/usr/local/google/src/go/6g
0066c000-0066d000 r--p 0006c000 08:06 2730103
/usr/local/google/src/go/6g
0066d000-00674000 rw-p 0006d000 08:06 2730103
/usr/local/google/src/go/6g
00674000-0071d000 rw-p 00000000 00:00 0 [heap]
7ffff77d6000-7ffff7950000 r-xp 00000000 08:01 1352099
/lib/libc-2.11.1.so
7ffff7950000-7ffff7b4f000 ---p 0017a000 08:01 1352099
/lib/libc-2.11.1.so <-- it's here, the page is mapped as PROT_NONE
7ffff7b4f000-7ffff7b53000 r--p 00179000 08:01 1352099
/lib/libc-2.11.1.so
7ffff7b53000-7ffff7b54000 rw-p 0017d000 08:01 1352099
/lib/libc-2.11.1.so
7ffff7b54000-7ffff7b59000 rw-p 00000000 00:00 0
7ffff7b59000-7ffff7bdb000 r-xp 00000000 08:01 1352103
/lib/libm-2.11.1.so
7ffff7bdb000-7ffff7dda000 ---p 00082000 08:01 1352103
/lib/libm-2.11.1.so
7ffff7dda000-7ffff7ddb000 r--p 00081000 08:01 1352103
/lib/libm-2.11.1.so
7ffff7ddb000-7ffff7ddc000 rw-p 00082000 08:01 1352103
/lib/libm-2.11.1.so
7ffff7ddc000-7ffff7dfc000 r-xp 00000000 08:01 1352096
/lib/ld-2.11.1.so
7ffff7ee1000-7ffff7fda000 rw-p 00000000 00:00 0
7ffff7ff9000-7ffff7ffb000 rw-p 00000000 00:00 0
7ffff7ffb000-7ffff7ffc000 r-xp 00000000 00:00 0 [vdso]
7ffff7ffc000-7ffff7ffd000 r--p 00020000 08:01 1352096
/lib/ld-2.11.1.so
7ffff7ffd000-7ffff7ffe000 rw-p 00021000 08:01 1352096
/lib/ld-2.11.1.so
7ffff7ffe000-7ffff7fff000 rw-p 00000000 00:00 0
7ffffffea000-7ffffffff000 rw-p 00000000 00:00 0 [stack]
ffffffffff600000-ffffffffff601000 r-xp 00000000 00:00 0 [vsyscall]
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