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

On 2022/08/23 11:58, lijiang wrote: > Hi, Kazu > Thank you for the comment. > On Mon, Aug 22, 2022 at 2:41 PM HAGIO KAZUHITO(萩尾 一仁) < k-hagio-ab(a)nec.com&gt; > wrote: > >> On 2022/08/11 19:02, Lianbo Jiang wrote: >>> 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) >> >> What does "the lack of debuginfo package" mean? I tried to reproduce >> > > Here, the kpatch is built as separate packages, and the debug information is > shipped into the debuginfo package. > > When trying to reproduce it, do not install its debuginfo on your system. > > I guess that you may try to strip the debuginfo from the test.ko, maybe it > can be > also reproduced. Thanks, I could reproduce it with this way:

# objcopy --only-keep-debug test.ko test.ko.debug # objcopy --strip-debug test.ko # objcopy --add-gnu-debuglink=test.ko.debug test.ko # mv test.ko.debug test.ko.debug.bak # insmod test.ko # crash ... crash> mod -s test test.ko terminate called after throwing an instance of 'std::logic_error' what(): basic_string::_M_construct null not valid Aborted (core dumped) > 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: So more generally, how about this?

When trying to load a module with "mod -s" without its separated debug info file installed, the crash utility will abort as below: Thanks, Kazu > > >> this with my test module, but could not. How can I reproduce this? >> >> crash> mod -s test test.ko >> MODULE NAME BASE SIZE >> OBJECT FILE >> ffffffffc07c8040 test ffffffffc07c6000 16384 test.ko >> >> >> And the gdb-10.2.patch already has a patch for gdb-10.2/gdb/symfile.c, >> it would be better to restore the file before re-patching. >> >> tar xvzmf gdb-10.2.tar.gz \ >> + gdb-10.2/gdb/symfile.c \ >> gdb-10.2/gdb/Makefile.in >> > > Yes, that would be fine. >

> Thanks. > Lianbo > > >> Thanks, >> Kazu >> >>> >>> 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 >> >> >> >> Hi, Kazu >> Thank you for the comment. >> On Mon, Aug 22, 2022 at 2:41 PM HAGIO KAZUHITO(萩尾 一仁) < k-hagio-ab(a)nec.com <mailto:k-hagio-ab@nec.com>> wrote: >> >> On 2022/08/11 19:02, Lianbo Jiang wrote: >> > 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) >> >> What does "the lack of debuginfo package" mean? I tried to reproduce >> >> >> Here, the kpatch is built as separate packages, and the debug information is >> shipped into the debuginfo package. >> >> When trying to reproduce it, do not install its debuginfo on your system. >> >> I guess that you may try to strip the debuginfo from the test.ko, maybe it can be >> also reproduced. >> >> this with my test module, but could not. How can I reproduce this? >> >> crash> mod -s test test.ko >> MODULE NAME BASE SIZE OBJECT FILE >> ffffffffc07c8040 test ffffffffc07c6000 16384 test.ko >> >> >> And the gdb-10.2.patch already has a patch for gdb-10.2/gdb/symfile.c, >> it would be better to restore the file before re-patching. >> >> tar xvzmf gdb-10.2.tar.gz \ >> + gdb-10.2/gdb/symfile.c \ >> gdb-10.2/gdb/Makefile.in >> >> >> Yes, that would be fine. >> Thanks. >> Lianbo >> >> >> Thanks, >> Kazu >> >> > >> > 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 <mailto: lijiang(a)redhat.com&gt;&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 >>