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Rtoax / ulpatch

ULPatch is open source user space live patch tool.
https://rtoax.github.io/ulpatch/
GNU General Public License v2.0
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Ubuntu23.04/x86_64: /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2: unable to find lowest load address. #15

Closed Rtoax closed 2 months ago

Rtoax commented 2 months ago

See also https://github.com/Rtoax/ulpatch/issues/14

Rtoax commented 2 months ago 
ulpatch/tests/hello$ sudo ./test.sh -u patch-pthread.ulp -d
...
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from , addr 7f0cd6b75000
15:29:11 [DEBUG][ehdr.c ehdr_magic_ok:20] Wrong ELF magic
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from , addr 7f0cd6b8c000
15:29:11 [DEBUG][ehdr.c ehdr_magic_ok:20] Wrong ELF magic
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2, addr 7f0cd6b8e000
15:29:11 [DEBUG][task.c vma_peek_phdr:451] 7f0cd6b8e000 /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 is ELF
15:29:11 [DEBUG][task.c vma_peek_phdr:500] peek phdr from target addr 7f0cd6b8e040, len 616
15:29:11 [DEBUG][task.c vma_peek_phdr:578] Get /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 voffset 1000
15:29:11 [DEBUG][task.c vma_peek_phdr:578] Get /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 voffset 29000
15:29:11 [DEBUG][task.c vma_peek_phdr:578] Get /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 voffset 33a20
15:29:11 [ INFO][task.c vma_peek_phdr:628] /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 vma start 7f0cd6b8e000, load_offset 7f0cd6b8e000
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2, addr 7f0cd6b8f000
15:29:11 [DEBUG][ehdr.c ehdr_magic_ok:20] Wrong ELF magic
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2, addr 7f0cd6bb7000
15:29:11 [DEBUG][task.c vma_peek_phdr:451] 7f0cd6bb7000 /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2 is ELF
15:29:11 [DEBUG][task.c vma_peek_phdr:500] peek phdr from target addr 7f0cd6bb7016, len 504
15:29:11 [ERROR][task.c vma_peek_phdr:591][Bad file descriptor] /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2: unable to find lowest load address.
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2, addr 7f0cd6bc1000
15:29:11 [DEBUG][ehdr.c ehdr_magic_ok:20] Wrong ELF magic
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2, addr 7f0cd6bc3000
15:29:11 [DEBUG][ehdr.c ehdr_magic_ok:20] Wrong ELF magic
15:29:11 [ WARN][task.c vma_peek_phdr:416] not support stack
15:29:11 [ WARN][task.c vma_peek_phdr:416] not support vvar
15:29:11 [DEBUG][task.c vma_peek_phdr:438] Peek a phdr from [vdso], addr 7ffc6afa2000
15:29:11 [DEBUG][task.c vma_peek_phdr:451] 7ffc6afa2000 [vdso] is ELF
15:29:11 [DEBUG][task.c vma_peek_phdr:500] peek phdr from target addr 7ffc6afa2040, len 224
15:29:11 [ INFO][task.c vma_peek_phdr:628] [vdso] vma start 7ffc6afa2000, load_offset 7ffc6afa2000
15:29:11 [ WARN][task.c vma_peek_phdr:416] not support vsyscall
15:29:11 [DEBUG][task.c load_self_vma_symbols:731] hello undef symbol: sleep 0
15:29:11 [DEBUG][task.c load_self_vma_symbols:731] hello undef symbol: sleep@GLIBC_2.2.5 0
15:29:11 [DEBUG][task.c load_self_vma_symbols:731] hello undef symbol: signal 0
15:29:11 [DEBUG][task.c load_self_vma_symbols:731] hello undef symbol: signal@GLIBC_2.2.5 0
15:29:11 [DEBUG][task.c load_self_vma_symbols:744] SELF routine 127f
15:29:11 [DEBUG][task.c task_vma_link_symbol:707] hello: add symbol routine addr 127f success.
15:29:11 [DEBUG][task.c load_self_vma_symbols:744] SELF sig_handler 11f9
15:29:11 [DEBUG][task.c task_vma_link_symbol:707] hello: add symbol sig_handler addr 11f9 success.
15:29:11 [DEBUG][task.c load_self_vma_symbols:731] hello undef symbol: puts 0
15:29:11 [DEBUG][task.c load_self_vma_symbols:731] hello undef symbol: puts@GLIBC_2.2.5 0
Rtoax commented 2 months ago

/proc/PID/maps

$ cat /proc/$(pidof hello)/maps
561a233d9000-561a233da000 r--p 00000000 fc:02 798333                     /home/rongtao/Git/ulpatch/tests/hello/hello
561a233da000-561a233db000 r-xp 00001000 fc:02 798333                     /home/rongtao/Git/ulpatch/tests/hello/hello
561a233db000-561a233dc000 r--p 00002000 fc:02 798333                     /home/rongtao/Git/ulpatch/tests/hello/hello
561a233dc000-561a233dd000 r--p 00002000 fc:02 798333                     /home/rongtao/Git/ulpatch/tests/hello/hello
561a233dd000-561a233de000 rw-p 00003000 fc:02 798333                     /home/rongtao/Git/ulpatch/tests/hello/hello
561a23425000-561a23446000 rw-p 00000000 00:00 0                          [heap]
7f6a499fd000-7f6a499fe000 ---p 00000000 00:00 0 
7f6a499fe000-7f6a4a1fe000 rw-p 00000000 00:00 0 
7f6a4a1fe000-7f6a4a1ff000 ---p 00000000 00:00 0 
7f6a4a1ff000-7f6a4a9ff000 rw-p 00000000 00:00 0 
7f6a4a9ff000-7f6a4aa00000 ---p 00000000 00:00 0 
7f6a4aa00000-7f6a4b200000 rw-p 00000000 00:00 0 
7f6a4b200000-7f6a4b222000 r--p 00000000 fc:02 4325769                    /usr/lib/x86_64-linux-gnu/libc.so.6
7f6a4b222000-7f6a4b39a000 r-xp 00022000 fc:02 4325769                    /usr/lib/x86_64-linux-gnu/libc.so.6
7f6a4b39a000-7f6a4b3f2000 r--p 0019a000 fc:02 4325769                    /usr/lib/x86_64-linux-gnu/libc.so.6
7f6a4b3f2000-7f6a4b3f6000 r--p 001f1000 fc:02 4325769                    /usr/lib/x86_64-linux-gnu/libc.so.6
7f6a4b3f6000-7f6a4b3f8000 rw-p 001f5000 fc:02 4325769                    /usr/lib/x86_64-linux-gnu/libc.so.6
7f6a4b3f8000-7f6a4b405000 rw-p 00000000 00:00 0 
7f6a4b5be000-7f6a4b5c1000 rw-p 00000000 00:00 0 
7f6a4b5d5000-7f6a4b5d7000 rw-p 00000000 00:00 0 
7f6a4b5d7000-7f6a4b5d8000 r--p 00000000 fc:02 4325753                    /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
7f6a4b5d8000-7f6a4b600000 r-xp 00001000 fc:02 4325753                    /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
7f6a4b600000-7f6a4b60a000 r--p 00029000 fc:02 4325753                    /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
7f6a4b60a000-7f6a4b60c000 r--p 00033000 fc:02 4325753                    /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
7f6a4b60c000-7f6a4b60e000 rw-p 00035000 fc:02 4325753                    /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
7ffe432cd000-7ffe432ee000 rw-p 00000000 00:00 0                          [stack]
7ffe433bc000-7ffe433c0000 r--p 00000000 00:00 0                          [vvar]
7ffe433c0000-7ffe433c2000 r-xp 00000000 00:00 0                          [vdso]
ffffffffff600000-ffffffffff601000 --xp 00000000 00:00 0                  [vsyscall]

ultask

$ sudo ultask -p $(pidof hello) --dump-vma 7f6a4b600000-7f6a4b60a000 -o a.elf
/usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2: unable to find lowest load address(ffffffffffffffff).
      TYPE:            Start              End   Perm Role
                       pgoff          Voffset Name
        ld: 00007f6a4b600000-00007f6a4b60a000   r--p E-P-
            0000000000029000 0000000000029000 /usr/lib/x86_64-linux-gnu/ld-linux-x86-64.so.2
            load_offset = 0x0
ELF Header:
 Magic:   7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00
 Class:                             ELF64
 Data:                              2's complement, little endian
 Version:                           1 (current)
 OS/ABI:                            UNIX - System V
 ABI Version:                       0
 Type:                              No file type
 Machine:                           No machine type
 Version:                           0x0
 Entry point address:               0x0
 Start of program headers:          22 (bytes into file)
 Start of section headers:          26 (bytes into file)
 Flags:                             0x5
 Size of this header:               0 (bytes)
 Size of program headers:           0 (bytes)
 Number of program headers:         9
 Size of section headers:           0 (bytes)
 Number of section headers:         0
 Section header string table index: 0

hexdump

$ hexdump -C a.elf | more
00000000  7f 45 4c 46 02 01 01 00  00 00 00 00 00 00 00 00  |.ELF............|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  16 00 00 00 00 00 00 00  1a 00 00 00 00 00 00 00  |................|
00000030  05 00 00 00 00 00 00 00  09 00 00 00 00 00 00 00  |................|
00000040  2f 6c 69 62 2f 78 38 36  5f 36 34 2d 6c 69 6e 75  |/lib/x86_64-linu|
00000050  78 2d 67 6e 75 2f 00 2f  75 73 72 2f 6c 69 62 2f  |x-gnu/./usr/lib/|
00000060  78 38 36 5f 36 34 2d 6c  69 6e 75 78 2d 67 6e 75  |x86_64-linux-gnu|
00000070  2f 00 2f 6c 69 62 2f 00  2f 75 73 72 2f 6c 69 62  |/./lib/./usr/lib|

Thus

Thus, the 7f6a4b600000-7f6a4b60a000 vma is Bad ELF, we should skip it.

Rtoax commented 2 months ago

Fixed in https://github.com/Rtoax/ulpatch/commit/fc6b00f87c1d2a32641671112bbc0e492ff73894