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cisco-open / llvm-crash-analyzer

llvm crash analysis
Apache License 2.0
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[lldb-crash-server] Add minimal support for reading memory #54

Closed niktesic closed 12 months ago

niktesic commented 12 months ago

Description

Intercept memory reads on the lldb-crash-server side to access memory context from the core-file process. That is done by overriding the ReadMemory method of the CoreFileProtocol, a derivate of NativeProcessProtocol.

Test example

TARGET:

$ lldb-crash-server g --core-file core.m localhost:1234 ./m
Loading core-file core.m
warning: No debugging symbols found in libc.so.6
core-file processed.

lldb-server-local_build
Connection established.

HOST:

$ gdb
GNU gdb (GDB) 14.0.50.20230607-git
...
(gdb) set architecture i386:x86-64
The target architecture is set to "i386:x86-64".
(gdb) target remote localhost:1234
Remote debugging using localhost:1234
warning: while parsing target description (at line 1): Target description specified unknown architecture "x86_64"
warning: Could not load XML target description; ignoring
warning: No executable has been specified and target does not support
determining executable automatically.  Try using the "file" command.
0x0000000000400550 in ?? ()
(gdb) symbol-file ./m
Reading symbols from ./m...
(gdb) bt
#0  0x0000000000400550 in crash (str=0x7fffa0920688) at m.c:7
#1  0x000000000040058f in main () at m.c:16
(gdb) disassemble
Dump of assembler code for function crash:
   0x0000000000400540 <+0>:     push   %rbp
   0x0000000000400541 <+1>:     mov    %rsp,%rbp
   0x0000000000400544 <+4>:     mov    %rdi,-0x8(%rbp)
   0x0000000000400548 <+8>:     mov    -0x8(%rbp),%rax
   0x000000000040054c <+12>:    mov    0x8(%rax),%rax
=> 0x0000000000400550 <+16>:    movl   $0x4,(%rax)
   0x0000000000400556 <+22>:    pop    %rbp
   0x0000000000400557 <+23>:    ret

CORE-FILE LOADED BY GDB:

$ gdb
GNU gdb (GDB) 14.0.50.20230607-git
Reading symbols from ./m...
[New LWP 2852139]
Core was generated by `./m'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  0x0000000000400550 in crash (str=0x7fffa0920688) at m.c:7
7         *str->x = 4; // crash - line 7
(gdb) bt
#0  0x0000000000400550 in crash (str=0x7fffa0920688) at m.c:7
#1  0x000000000040058f in main () at m.c:16
(gdb) disassemble
Dump of assembler code for function crash:
   0x0000000000400540 <+0>:     push   %rbp
   0x0000000000400541 <+1>:     mov    %rsp,%rbp
   0x0000000000400544 <+4>:     mov    %rdi,-0x8(%rbp)
   0x0000000000400548 <+8>:     mov    -0x8(%rbp),%rax
   0x000000000040054c <+12>:    mov    0x8(%rax),%rax
=> 0x0000000000400550 <+16>:    movl   $0x4,(%rax)
   0x0000000000400556 <+22>:    pop    %rbp
   0x0000000000400557 <+23>:    ret
End of assembler dump.