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inexplicable SIGSEGV (Address boundary error)
Raw
gdb.out
Newlines addedfor clarity. Some inconsequential output removed.
https://github.com/fenrus75/powertop/blob/master/src/perf/perf.cpp#L233
$ sudo gdb ./powertop
(gdb) break perf.cpp:233
Breakpoint 1 at 0x435f0: file perf/perf.cpp, line 233.
(gdb) run
[first break is a good run of the function]
Breakpoint 1, perf_event::process (this=0x5555555f0800, cookie=cookie@entry=0x5555555f0910) at perf/perf.cpp:233
233 if (perf_fd < 0)
(gdb) set disassemble-next-line on
(gdb) info registers
rax 0x1 1
rbx 0x5555555f08c0 93824992872640
rcx 0x5555555f3030 93824992882736
rdx 0x0 0
rsi 0x5555555f0910 93824992872720
rdi 0x5555555f0800 93824992872448
rbp 0x7fffffffc440 0x7fffffffc440
rsp 0x7fffffffc3a8 0x7fffffffc3a8
r8 0x7 7
r9 0x6 6
r10 0x0 0
r11 0x246 582
r12 0x5555555f0910 93824992872720
r13 0x0 0
r14 0x1 1
r15 0x0 0
rip 0x5555555975f0 0x5555555975f0 <perf_event::process(void*)>
eflags 0x206 [ PF IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
(gdb) stepi 14
0x0000555555597617 233 if (perf_fd < 0)
0x00005555555975f0 <perf_event::process(void*)+0>: 8b 47 08 mov 0x8(%rdi),%eax
0x00005555555975f3 <perf_event::process(void*)+3>: 85 c0 test %eax,%eax
0x00005555555975f5 <perf_event::process(void*)+5>: 0f 88 eb 00 00 00 js 0x5555555976e6 <perf_event::process(void*)+246>
0x00005555555975fb <perf_event::process(void*)+11>: 55 push %rbp
0x00005555555975fc <perf_event::process(void*)+12>: 48 89 e5 mov %rsp,%rbp
0x00005555555975ff <perf_event::process(void*)+15>: 41 57 push %r15
0x0000555555597601 <perf_event::process(void*)+17>: 49 89 ff mov %rdi,%r15
0x0000555555597604 <perf_event::process(void*)+20>: 41 56 push %r14
0x0000555555597606 <perf_event::process(void*)+22>: 41 55 push %r13
0x0000555555597608 <perf_event::process(void*)+24>: 41 54 push %r12
0x000055555559760a <perf_event::process(void*)+26>: 53 push %rbx
0x000055555559760b <perf_event::process(void*)+27>: 48 83 ec 18 sub $0x18,%rsp
0x000055555559760f <perf_event::process(void*)+31>: 48 89 75 c8 mov %rsi,-0x38(%rbp)
0x0000555555597613 <perf_event::process(void*)+35>: 4d 8b 6f 20 mov 0x20(%r15),%r13
=> 0x0000555555597617 <perf_event::process(void*)+39>: 4d 8b a5 00 04 00 00 mov 0x400(%r13),%r12
0x000055555559761e <perf_event::process(void*)+46>: 66 90 xchg %ax,%ax
(gdb) info registers
rax 0xa0 160
rbx 0x5555555f08c0 93824992872640
rcx 0x5555555f3030 93824992882736
rdx 0x0 0
rsi 0x5555555f0910 93824992872720
rdi 0x5555555f0800 93824992872448
rbp 0x7fffffffc3a0 0x7fffffffc3a0
rsp 0x7fffffffc360 0x7fffffffc360
r8 0x7 7
r9 0x6 6
r10 0x0 0
r11 0x246 582
r12 0x5555555f0910 93824992872720
r13 0x5555555faca0 93824992914592
r14 0x1 1
r15 0x5555555f0800 93824992872448
rip 0x555555597617 0x555555597617 <perf_event::process(void*)+39>
eflags 0x206 [ PF IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
(gdb) continue
[second time it breaks is the problem]
Continuing.
Breakpoint 1, perf_event::process (this=0x5555555f1bb0, cookie=cookie@entry=0x5555555f0910) at perf/perf.cpp:233
233 if (perf_fd < 0)
=> 0x00005555555975f0 <perf_event::process(void*)+0>: 8b 47 08 mov 0x8(%rdi),%eax
0x00005555555975f3 <perf_event::process(void*)+3>: 85 c0 test %eax,%eax
0x00005555555975f5 <perf_event::process(void*)+5>: 0f 88 eb 00 00 00 js 0x5555555976e6 <perf_event::process(void*)+246>
0x00005555555975fb <perf_event::process(void*)+11>: 55 push %rbp
0x00005555555975fc <perf_event::process(void*)+12>: 48 89 e5 mov %rsp,%rbp
0x00005555555975ff <perf_event::process(void*)+15>: 41 57 push %r15
0x0000555555597601 <perf_event::process(void*)+17>: 49 89 ff mov %rdi,%r15
0x0000555555597604 <perf_event::process(void*)+20>: 41 56 push %r14
0x0000555555597606 <perf_event::process(void*)+22>: 41 55 push %r13
0x0000555555597608 <perf_event::process(void*)+24>: 41 54 push %r12
0x000055555559760a <perf_event::process(void*)+26>: 53 push %rbx
0x000055555559760b <perf_event::process(void*)+27>: 48 83 ec 18 sub $0x18,%rsp
0x000055555559760f <perf_event::process(void*)+31>: 48 89 75 c8 mov %rsi,-0x38(%rbp)
0x0000555555597613 <perf_event::process(void*)+35>: 4d 8b 6f 20 mov 0x20(%r15),%r13
0x0000555555597617 <perf_event::process(void*)+39>: 4d 8b a5 00 04 00 00 mov 0x400(%r13),%r12
0x000055555559761e <perf_event::process(void*)+46>: 66 90 xchg %ax,%ax
(gdb) info registers
rax 0x18 24
rbx 0x5555555f08c0 93824992872640
rcx 0x5555555f3030 93824992882736
rdx 0x1 1
rsi 0x5555555f0910 93824992872720
rdi 0x5555555f1bb0 93824992877488
rbp 0x7fffffffc440 0x7fffffffc440
rsp 0x7fffffffc3a8 0x7fffffffc3a8
r8 0x7 7
r9 0x6 6
r10 0x0 0
r11 0x246 582
r12 0x5555555f0910 93824992872720
r13 0x1 1
r14 0x1 1
r15 0x0 0
rip 0x5555555975f0 0x5555555975f0 <perf_event::process(void*)>
eflags 0x202 [ IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
(gdb) stepi 14
0x0000555555597617 233 if (perf_fd < 0)
0x00005555555975f0 <perf_event::process(void*)+0>: 8b 47 08 mov 0x8(%rdi),%eax
0x00005555555975f3 <perf_event::process(void*)+3>: 85 c0 test %eax,%eax
0x00005555555975f5 <perf_event::process(void*)+5>: 0f 88 eb 00 00 00 js 0x5555555976e6 <perf_event::process(void*)+246>
0x00005555555975fb <perf_event::process(void*)+11>: 55 push %rbp
0x00005555555975fc <perf_event::process(void*)+12>: 48 89 e5 mov %rsp,%rbp
0x00005555555975ff <perf_event::process(void*)+15>: 41 57 push %r15
0x0000555555597601 <perf_event::process(void*)+17>: 49 89 ff mov %rdi,%r15
0x0000555555597604 <perf_event::process(void*)+20>: 41 56 push %r14
0x0000555555597606 <perf_event::process(void*)+22>: 41 55 push %r13
0x0000555555597608 <perf_event::process(void*)+24>: 41 54 push %r12
0x000055555559760a <perf_event::process(void*)+26>: 53 push %rbx
0x000055555559760b <perf_event::process(void*)+27>: 48 83 ec 18 sub $0x18,%rsp
0x000055555559760f <perf_event::process(void*)+31>: 48 89 75 c8 mov %rsi,-0x38(%rbp)
0x0000555555597613 <perf_event::process(void*)+35>: 4d 8b 6f 20 mov 0x20(%r15),%r13
=> 0x0000555555597617 <perf_event::process(void*)+39>: 4d 8b a5 00 04 00 00 mov 0x400(%r13),%r12
0x000055555559761e <perf_event::process(void*)+46>: 66 90 xchg %ax,%ax
(gdb) info registers
rax 0xa1 161
rbx 0x5555555f08c0 93824992872640
rcx 0x5555555f3030 93824992882736
rdx 0x1 1
rsi 0x5555555f0910 93824992872720
rdi 0x5555555f1bb0 93824992877488
rbp 0x7fffffffc3a0 0x7fffffffc3a0
rsp 0x7fffffffc360 0x7fffffffc360
r8 0x7 7
r9 0x6 6
r10 0x0 0
r11 0x246 582
r12 0x5555555f0910 93824992872720
r13 0x632f7265776f702f 7147056913781321775
r14 0x1 1
r15 0x5555555f1bb0 93824992877488
rip 0x555555597617 0x555555597617 <perf_event::process(void*)+39>
eflags 0x206 [ PF IF ]
cs 0x33 51
ss 0x2b 43
ds 0x0 0
es 0x0 0
fs 0x0 0
gs 0x0 0
(gdb) print *this
$1 = {_vptr.perf_event = 0x5555555d6898 <vtable for perf_bundle_event+16>, perf_fd = 161, perf_mmap = 0xffffffffffffffff,
data_mmap = 0x73746e6576652f67, pc = 0x632f7265776f702f, bufsize = 128, name = 0x5555555f2370 "power/cpu_idle",
cpu = 1, trace_type = 454, static pevent = 0x5555555f1aa0}
[notice the very large value in this->pc which has ended up in r13 and is going to cause the address boundary error
as soon as access to `0x400(%r13)` is attempted]
(gdb) stepi
Program received signal SIGSEGV, Segmentation fault.
0x0000555555597617 in perf_event::process (this=0x5555555f1bb0, cookie=cookie@entry=0x5555555f0910) at perf/perf.cpp:233
233 if (perf_fd < 0)
(gdb) print $_siginfo
$2 = {si_signo = 11, si_errno = 0, si_code = 128, _sifields = {_pad = {0 <repeats 28 times>}, _kill = {si_pid = 0,
si_uid = 0}, _timer = {si_tid = 0, si_overrun = 0, si_sigval = {sival_int = 0, sival_ptr = 0x0}}, _rt = {
si_pid = 0, si_uid = 0, si_sigval = {sival_int = 0, sival_ptr = 0x0}}, _sigchld = {si_pid = 0, si_uid = 0,
si_status = 0, si_utime = 0, si_stime = 0}, _sigfault = {si_addr = 0x0, _addr_lsb = 0, _addr_bnd = {_lower
= 0x0, _upper = 0x0}}, _sigpoll = {si_band = 0, si_fd = 0}}}
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