Re: [Crash-utility] [PATCH] gdb: fix for assigning NULL to std::string

When the lack of debuginfo package, try to load its module with the "mod -s xxx" in crash, it will cause the crash utility coredump as below: crash> mod -s kpatch_test kpatch_test.ko ... terminate called after throwing an instance of 'std::logic_error' what(): basic_string::_M_construct null not valid Aborted (core dumped)

Let's return the std::string() instead of std::string(NULL) when a string is null, because the check_specified_kernel_debug_file() may return NULL. Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com&gt; --- (gdb) bt #0 __pthread_kill_implementation (threadid=<optimized out>, signo=<optimized out>, no_tid=<optimized out>) at pthread_kill.c:44 #1 0x00007fff8b48223c in __GI_raise (sig=<optimized out>) at ../sysdeps/posix/raise.c:26 #2 0x00007fff8b45c70c in __GI_abort () at abort.c:79 #3 0x00007fff8b8cbee8 in __gnu_cxx::__verbose_terminate_handler () at ../../../../libstdc++-v3/libsupc++/vterminate.cc:95 #4 0x00007fff8b8c74e4 in __cxxabiv1::__terminate (handler=<optimized out>) at ../../../../libstdc++-v3/libsupc++/eh_terminate.cc:48 #5 0x00007fff8b8c75b0 in std::terminate () at ../../../../libstdc++-v3/libsupc++/eh_terminate.cc:58 #6 0x00007fff8b8c7a94 in __cxxabiv1::__cxa_throw (obj=<optimized out>, tinfo=0x7fff8bac48b0 <typeinfo for std::logic_error>, dest=0x7fff8b8e93d0 <std::logic_error::~logic_error()>) at ../../../../libstdc++-v3/libsupc++/eh_throw.cc:95 #7 0x00007fff8b889370 in std::__throw_logic_error (__s=0x1312445d0 "basic_string::_M_construct null not valid") at ../../../../../libstdc++-v3/src/c++11/functexcept.cc:70 #8 0x000000013105d448 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char const*>(char const*, char const*, std::forward_iterator_tag) [clone .constprop.0] (this=0x7fffdde41128, __beg=<optimized out>, __end=<optimized out>) at /usr/include/c++/11/bits/basic_string.tcc:212 #9 0x0000000130da805c in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string<std::allocator<char> > (__a=..., __s=<optimized out>, this=0x7fffdde41128) at /usr/include/c++/11/bits/basic_string.h:539 #10 find_separate_debug_file_by_debuglink[abi:cxx11](objfile*) (objfile=<optimized out>) at symfile.c:1613 #11 0x0000000130b41028 in elf_symfile_read (objfile=0x1003ccd5bb0, symfile_flags=...) at elfread.c:1304 #12 0x0000000130da68b8 in read_symbols (objfile=<optimized out>, objfile@entry=0x1003ccd5bb0, add_flags=..., add_flags@entry=...) at symfile.c:800 #13 0x0000000130da5f48 in syms_from_objfile_1 (add_flags=..., addrs=0x7fffdde41450, objfile=0x1003ccd5bb0) at symfile.c:997 #14 syms_from_objfile (add_flags=..., addrs=0x7fffdde41450, objfile=0x1003ccd5bb0) at symfile.c:1014 #15 symbol_file_add_with_addrs (abfd=<optimized out>, name=name@entry=0x1003db636a0 "kpatch_test.ko", add_flags=add_flags@entry=..., addrs=addrs@entry=0x7fffdde41450, flags=..., flags@entry=..., parent=parent@entry=0x0) at symfile.c:1123 #16 0x0000000130da86e8 in symbol_file_add_from_bfd (parent=0x0, flags=..., addrs=0x7fffdde41450, add_flags=..., name=0x1003db636a0 "kpatch_test.ko", abfd=<optimized out>) at symfile.c:1204 #17 symbol_file_add (name=0x1003db636a0 "kpatch_test.ko", add_flags=..., addrs=0x7fffdde41450, flags=...) at symfile.c:1217 #18 0x0000000130dade4c in add_symbol_file_command (args=<optimized out>, from_tty=<optimized out>) at symfile.c:2388 #19 0x0000000130a3e04c in do_const_cfunc (c=<optimized out>, args=<optimized out>, from_tty=<optimized out>) at cli/cli-decode.c:95 #20 0x0000000130a40c48 in cmd_func (cmd=<optimized out>, args=<optimized out>, from_tty=<optimized out>) at cli/cli-decode.c:2181 #21 0x0000000130e2344c in execute_command (p=<optimized out>, from_tty=<optimized out>) at top.c:668 #22 0x0000000130dc9d9c in gdb_add_symbol_file (req=0x7fffdde41b10) at symtab.c:7436 #23 gdb_command_funnel_1 (req=req@entry=0x7fffdde41b10) at symtab.c:7004 #24 0x0000000130dcaa40 in gdb_command_funnel (req=0x7fffdde41b10) at symtab.c:6954 #25 0x00000001308c78ec in gdb_interface (req=0x7fffdde41b10) at ../../gdb_interface.c:409 #26 0x0000000130942adc in add_symbol_file (lm=0x1003ff62098) at ../../symbols.c:11914 #27 0x00000001309442a0 in load_module_symbols (modref=<optimized out>, namelist=0x13146b682 <program_context+258> "kpatch_test.ko", base_addr=13837309855101681664) at ../../symbols.c:11852 #28 0x000000013089f7b0 in do_module_cmd (flag=3, modref=<optimized out>, address=<optimized out>, objfile=<optimized out>, tree=<optimized out>) at ../../kernel.c:4602 #29 0x000000013089da6c in cmd_mod () at ../../kernel.c:4204 #30 0x00000001307e27bc in exec_command () at ../../main.c:892 #31 0x000000013094d004 in exec_input_file () at ../../cmdline.c:1489 #32 0x00000001307e2214 in is_input_file () at ../../main.c:988 #33 exec_command () at ../../main.c:899 #34 0x00000001307e2bbc in main_loop () at ../../main.c:839 #35 0x0000000130c30654 in captured_main (data=<optimized out>) at main.c:1284 #36 gdb_main (args=<optimized out>) at main.c:1313 #37 0x00000001308c5fbc in gdb_main_entry (argv=0x7fffdde45ca8, argc=2) at main.c:1338 #38 gdb_main_loop (argc=2, argv=0x7fffdde45ca8) at ../../gdb_interface.c:81 #39 0x00000001307d1158 in main (argc=<optimized out>, argv=0x7fffdde45ca8) at ../../main.c:720 (gdb) gdb-10.2.patch | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/gdb-10.2.patch b/gdb-10.2.patch index 577f5e45fc5a..3e0569d8ea98 100644 --- a/gdb-10.2.patch +++ b/gdb-10.2.patch @@ -1650,3 +1650,13 @@ exit 0 c_print_type_1 (type->field (i).type (), TYPE_FIELD_NAME (type, i), +--- gdb-10.2/gdb/symfile.c.orig ++++ gdb-10.2/gdb/symfile.c +@@ -1610,7 +1610,7 @@ find_separate_debug_file_by_debuglink (struct objfile *objfile) + if (debugfile.empty ()) { + char *name_copy; + name_copy = check_specified_kernel_debug_file(); +- return std::string (name_copy); ++ return name_copy ? std::string (name_copy) : std::string (); + } + #endif