Incorrect PyRuntime symbol address for libpython 3.11 on linux

[yiding]

I ran into a case where py-spy computes the wrong address for PyRuntime and then fails to get the PyInterpreterState head ptr.

I suspect the issue is due to binary_parser.rs computes the address of PyRuntime given the symbol from the file. Possibly due to ASLR, but I have not looked too hard at this. However after disabling ASLR (via sudo sysctl -w kernel.randomize_va_space=0) py-spy works consistently.

Python version: 3.11.10
OS: linux, nix

py-spy debug output

[2024-12-04T00:06:07.953583877Z DEBUG py_spy::python_process_info] map: 00007f31d7000000-00007f31d720c000 r-- /home/yiding/.local/share/uv/python/cpython-3.11.10-linux-x86_64-gnu/lib/libpython
3.11.so.1.0                                                                                                                                                                                     
[2024-12-04T00:06:07.953633198Z DEBUG py_spy::python_process_info] map: 00007f31d720c000-00007f31d7f95000 r-x /home/yiding/.local/share/uv/python/cpython-3.11.10-linux-x86_64-gnu/lib/libpython
3.11.so.1.0                                                                                                                                                                                     
[2024-12-04T00:06:07.953680154Z DEBUG py_spy::python_process_info] map: 00007f31d7f95000-00007f31d8513000 r-- /home/yiding/.local/share/uv/python/cpython-3.11.10-linux-x86_64-gnu/lib/libpython
3.11.so.1.0                                                                                                                                                                                     
[2024-12-04T00:06:07.953728270Z DEBUG py_spy::python_process_info] map: 00007f31d8513000-00007f31d85f1000 r-- /home/yiding/.local/share/uv/python/cpython-3.11.10-linux-x86_64-gnu/lib/libpython
3.11.so.1.0                                                                                                                                                                                     
[2024-12-04T00:06:07.953776521Z DEBUG py_spy::python_process_info] map: 00007f31d85f1000-00007f31d874b000 rw- /home/yiding/.local/share/uv/python/cpython-3.11.10-linux-x86_64-gnu/lib/libpython
3.11.so.1.0      
...
[2024-12-04T00:06:07.957910205Z INFO  py_spy::python_process_info] Found libpython binary @ /home/yiding/.local/share/uv/python/cpython-3.11.10-linux-x86_64-gnu/lib/libpython3.11.so.1.0
[2024-12-04T00:06:08.062811682Z INFO  py_spy::python_process_info] got symbol Py_GetVersion.version (0x00007f31d826bf60) from libpython binary
[2024-12-04T00:06:08.062874534Z INFO  py_spy::python_process_info] Getting version from symbol address
[2024-12-04T00:06:08.062949754Z INFO  py_spy::python_process_info] Getting version from python binary BSS
[2024-12-04T00:06:08.062968650Z INFO  py_spy::python_process_info] Failed to get version from BSS section: failed to find version string
[2024-12-04T00:06:08.062981071Z INFO  py_spy::python_process_info] Getting version from libpython BSS
[2024-12-04T00:06:08.063119642Z INFO  py_spy::version] Found matching version string '3.11.10 (main)'
[2024-12-04T00:06:08.063141548Z INFO  py_spy::python_spy] python version 3.11.10 detected
[2024-12-04T00:06:08.063156220Z INFO  py_spy::python_process_info] got symbol _PyRuntime (0x00007f31d8202850) from libpython binary
[2024-12-04T00:06:08.063239741Z WARN  py_spy::python_process_info] Interpreter address from _PyRuntime symbol is invalid 5f646e655f736576
[2024-12-04T00:06:08.063252698Z INFO  py_spy::python_process_info] Failed to find runtime address from symbols, scanning BSS section from main binary
[2024-12-04T00:06:08.063277528Z INFO  py_spy::python_process_info] Failed to get interpreter from binary BSS, scanning libpython BSS

Objdump output of the libpython binary:

architecture: i386:x86-64, flags 0x00000150:
HAS_SYMS, DYNAMIC, D_PAGED
start address 0x0000000000000000

Program Header:
    LOAD off    0x0000000000000000 vaddr 0x0000000000000000 paddr 0x0000000000000000 align 2**12
         filesz 0x000000000020baf8 memsz 0x000000000020baf8 flags r--
    LOAD off    0x000000000020c000 vaddr 0x000000000020c000 paddr 0x000000000020c000 align 2**12
         filesz 0x0000000000d88da9 memsz 0x0000000000d88da9 flags r-x
    LOAD off    0x0000000000f95000 vaddr 0x0000000000f95000 paddr 0x0000000000f95000 align 2**12
         filesz 0x000000000057d278 memsz 0x000000000057d278 flags r--
    LOAD off    0x0000000001512a00 vaddr 0x0000000001513a00 paddr 0x0000000001513a00 align 2**12
         filesz 0x0000000000236970 memsz 0x0000000000285e08 flags rw-
 DYNAMIC off    0x00000000015ef4c0 vaddr 0x00000000015f04c0 paddr 0x00000000015f04c0 align 2**3
         filesz 0x0000000000000220 memsz 0x0000000000000220 flags rw-
EH_FRAME off    0x0000000001359098 vaddr 0x0000000001359098 paddr 0x0000000001359098 align 2**2
         filesz 0x00000000000476ac memsz 0x00000000000476ac flags r--
   STACK off    0x0000000000000000 vaddr 0x0000000000000000 paddr 0x0000000000000000 align 2**4
         filesz 0x0000000000000000 memsz 0x0000000000000000 flags rw-
   RELRO off    0x0000000001512a00 vaddr 0x0000000001513a00 paddr 0x0000000001513a00 align 2**0
         filesz 0x00000000000dd600 memsz 0x00000000000dd600 flags r--

...

Sections:
Idx Name          Size      VMA               LMA               File off  Algn
  0 .gnu.hash     00003530  0000000000000200  0000000000000200  00000200  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  1 .dynsym       0000e7a8  0000000000003730  0000000000003730  00003730  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  2 .dynstr       0000a75c  0000000000011ed8  0000000000011ed8  00011ed8  2**0
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  3 .gnu.version  0000134e  000000000001c634  000000000001c634  0001c634  2**1
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  4 .gnu.version_r 000001c0  000000000001d988  000000000001d988  0001d988  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  5 .rela.dyn     001e62a0  000000000001db48  000000000001db48  0001db48  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  6 .rela.plt     00007d10  0000000000203de8  0000000000203de8  00203de8  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
  7 .init         0000001f  000000000020c000  000000000020c000  0020c000  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  8 .plt          00005370  000000000020c020  000000000020c020  0020c020  2**4
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
  9 .plt.got      00000120  0000000000211390  0000000000211390  00211390  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 10 .text         00d82da0  0000000000212000  0000000000212000  00212000  2**12
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 11 .fini         00000009  0000000000f94da0  0000000000f94da0  00f94da0  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, CODE
 12 .rodata       003c4098  0000000000f95000  0000000000f95000  00f95000  2**6
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 13 .eh_frame_hdr 000476ac  0000000001359098  0000000001359098  01359098  2**2
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 14 .eh_frame     00171b30  00000000013a0748  00000000013a0748  013a0748  2**3
                  CONTENTS, ALLOC, LOAD, READONLY, DATA
 15 .init_array   00000008  0000000001513a00  0000000001513a00  01512a00  2**3
                  CONTENTS, ALLOC, LOAD, DATA
 16 .fini_array   00000008  0000000001513a08  0000000001513a08  01512a08  2**3
                  CONTENTS, ALLOC, LOAD, DATA
 17 .data.rel.ro  000dcab0  0000000001513a10  0000000001513a10  01512a10  2**4
                  CONTENTS, ALLOC, LOAD, DATA
 18 .dynamic      00000220  00000000015f04c0  00000000015f04c0  015ef4c0  2**3
                  CONTENTS, ALLOC, LOAD, DATA
 19 .got          00000908  00000000015f06e0  00000000015f06e0  015ef6e0  2**3
                  CONTENTS, ALLOC, LOAD, DATA
 20 .got.plt      000029c8  00000000015f0fe8  00000000015f0fe8  015effe8  2**3
                  CONTENTS, ALLOC, LOAD, DATA
 21 .data         0012de8b  00000000015f39c0  00000000015f39c0  015f29c0  2**5
                  CONTENTS, ALLOC, LOAD, DATA
 22 .PyRuntime    00028b20  0000000001721850  0000000001721850  01720850  2**3
                  CONTENTS, ALLOC, LOAD, DATA
 23 .bss          0004f498  000000000174a370  000000000174a370  01749370  2**4
                  ALLOC
 24 .comment      00000043  0000000000000000  0000000000000000  01749370  2**0
                  CONTENTS, READONLY

...

0000000001721850 g     O .PyRuntime     0000000000028b20              _PyRuntime

Actual _PyRuntime address as computed by lldb:

(lldb) tar mo loo -s _PyRuntime -A
1 symbols match '_PyRuntime' in /home/yiding/.local/share/uv/python/cpython-3.11.10-linux-x86_64-gnu/lib/libpython3.11.so.1.0:
        Address: libpython3.11.so.1.0[0x0000000001721850] (libpython3.11.so.1.0.PT_LOAD[3]..PyRuntime + 0)
        Summary: libpython3.11.so.1.0`_PyRuntime

(lldb) p &_PyRuntime
(void **) 0x00007f31d8721850