** Description changed: + [Impact] + + * Debug files for ld-linux are not found by gdb making debugging + programs harder. + + [Test Plan] + + * Run a gdb debugging session and observe symbols from ld-linux shown + properly: + + root@ii:~# gdb -q /bin/date + Reading symbols from /bin/date... + Download failed: Function not implemented. Continuing without debug info for /bin/date. + (No debugging symbols found in /bin/date) + (gdb) starti + Starting program: /usr/bin/date + Download failed: Function not implemented. Continuing without debug info for /root/system-supplied DSO at 0x7ffff7fc6000. + + Program stopped. + 0x00007ffff7fc90d0 in _start () from /lib64/ld-linux-x86-64.so.2 + (gdb) b _dl_debug_state + Download failed: Function not implemented. Continuing without source file ./elf/dl-debug.c. + Breakpoint 1 at 0x7ffff7fd9fc0: file dl-debug.c, line 73. + (gdb) c + Continuing. + + Breakpoint 1, __GI__dl_debug_state () at dl-debug.c:73 + Download failed: Function not implemented. Continuing without source file ./elf/dl-debug.c. + 73 dl-debug.c: No such file or directory. + (gdb) bt + #0 __GI__dl_debug_state () at dl-debug.c:73 + #1 0x00007ffff7fcc18e in dl_main (phdr=<optimized out>, phnum=<optimized out>, user_entry=<optimized out>, auxv=<optimized out>) at rtld.c:1810 + #2 0x00007ffff7fe73df in _dl_sysdep_start (start_argptr=start_argptr@entry=0x7fffffffe5c0, dl_main=dl_main@entry=0x7ffff7fca610 <dl_main>) at ../elf/dl-sysdep.c:250 + #3 0x00007ffff7fca11a in _dl_start_final (arg=0x7fffffffe5c0) at rtld.c:490 + #4 _dl_start (arg=0x7fffffffe5c0) at rtld.c:583 + #5 0x00007ffff7fc90d8 in _start () from /lib64/ld-linux-x86-64.so.2 + #6 0x0000000000000001 in ?? () + #7 0x00007fffffffe7fa in ?? () + #8 0x0000000000000000 in ?? () + + + [Where problems could occur] + + * The fix is dropping using DH_COMPAT=8 for dh_strip. This override for + compat level was in place to work around a valgrind issue ( + https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=677876 ) that has been + fixed already in Ubuntu 18.04 and later releases. Almost all other + packages use the default compat level for dh_strip thus there is no + expected problem to occur. + + [Original Bug Text] + lsb_release -rd Description: Ubuntu 20.04.2 LTS Release: 20.04 Using gdb 9.2-0ubuntu1~20.04, libc6 and libc6-dbg 2.31-0ubuntu9.2 gdb -q /bin/date Reading symbols from /bin/date... (No debugging symbols found in /bin/date) (gdb) starti Starting program: /usr/bin/date Program stopped. 0x00007ffff7fd0100 in ?? () from /lib64/ld-linux-x86-64.so.2 (gdb) b _dl_debug_state Breakpoint 1 at 0x7ffff7fe11d0 (gdb) c Continuing. Breakpoint 1, 0x00007ffff7fe11d0 in _dl_debug_state () from /lib64/ld-linux-x86-64.so.2 (gdb) bt #0 0x00007ffff7fe11d0 in _dl_debug_state () from /lib64/ld-linux-x86-64.so.2 #1 0x00007ffff7fd2fd1 in ?? () from /lib64/ld-linux-x86-64.so.2 #2 0x00007ffff7febc3b in ?? () from /lib64/ld-linux-x86-64.so.2 #3 0x00007ffff7fd104c in ?? () from /lib64/ld-linux-x86-64.so.2 #4 0x00007ffff7fd0108 in ?? () from /lib64/ld-linux-x86-64.so.2 #5 0x0000000000000001 in ?? () #6 0x00007fffffffe58c in ?? () #7 0x0000000000000000 in ?? () Note that debug info for ld-linux is missing despite libc6-dbg being installed. (gdb) disable 1 (gdb) catch syscall exit_group Catchpoint 2 (syscall 'exit_group' [231]) (gdb) c Continuing. Sat Mar 6 22:47:08 PST 2021 Catchpoint 2 (call to syscall exit_group), __GI__exit (status=status@entry=0) at ../sysdeps/unix/sysv/linux/_exit.c:31 31 ../sysdeps/unix/sysv/linux/_exit.c: No such file or directory. Note that debug info for `libc.so.6` was loaded correctly, but debug info for ld-linux was not. (gdb) info shared From To Syms Read Shared Object Library 0x00007ffff7fd0100 0x00007ffff7ff2674 Yes (*) /lib64/ld-linux-x86-64.so.2 0x00007ffff7df4630 0x00007ffff7f6920d Yes /lib/x86_64-linux-gnu/libc.so.6 (*): Shared library is missing debugging information. ---- As far as I can tell, this is happening because libc6-dbg installs ld-2.31.so into the wrong place: dpkg -L libc6-dbg | grep /ld-2.31 /usr/lib/debug/lib/libc6-prof/x86_64-linux-gnu/ld-2.31.so /usr/lib/debug/lib/x86_64-linux-gnu/ld-2.31.so Since ld-linux resolves to /lib64/ld-linux-x86-64.so.2, GDB looks for debug symbols in the following paths: /lib64/.debug/ld-2.31.so /usr/lib/debug/lib64/ld-2.31.so /usr/lib/x86_64-linux-gnu/.debug/ld-2.31.so /usr/lib/debug/usr/lib/x86_64-linux-gnu/ld-2.31.so /usr/lib/x86_64-linux-gnu/.debug/ld-2.31.so /usr/lib/debug/usr/lib/x86_64-linux-gnu/ld-2.31.so None of these matches the actual installed path, so debug symbols are not loaded. P.S. Manually adding symbols via add-symbol-file /usr/lib/debug/lib/x86_64-linux-gnu/ld-2.31.so works fine, but this should be automatic. P.P.S. After running sudo mkdir /usr/lib/debug/lib64 sudo ln -s /usr/lib/debug/lib/x86_64-linux-gnu/ld-2.31.so /usr/lib/debug/lib64 things start working as expected: gdb -q /bin/date Reading symbols from /bin/date... (No debugging symbols found in /bin/date) (gdb) starti Starting program: /usr/bin/date Program stopped. 0x00007ffff7fd0100 in _start () from /lib64/ld-linux-x86-64.so.2 (gdb) b _dl_debug_state Breakpoint 1 at 0x7ffff7fe11d0: file dl-debug.c, line 73. (gdb) c Continuing. Breakpoint 1, __GI__dl_debug_state () at dl-debug.c:73 73 dl-debug.c: No such file or directory. (gdb) bt #0 __GI__dl_debug_state () at dl-debug.c:73 #1 0x00007ffff7fd2fd1 in dl_main (phdr=<optimized out>, phnum=<optimized out>, user_entry=<optimized out>, auxv=<optimized out>) at rtld.c:1661 #2 0x00007ffff7febc3b in _dl_sysdep_start (start_argptr=start_argptr@entry=0x7fffffffe390, dl_main=dl_main@entry=0x7ffff7fd15e0 <dl_main>) at ../elf/dl-sysdep.c:252 #3 0x00007ffff7fd104c in _dl_start_final (arg=0x7fffffffe390) at rtld.c:449 #4 _dl_start (arg=0x7fffffffe390) at rtld.c:539 #5 0x00007ffff7fd0108 in _start () from /lib64/ld-linux-x86-64.so.2 #6 0x0000000000000001 in ?? () #7 0x00007fffffffe5c8 in ?? () #8 0x0000000000000000 in ?? () ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: libc6-dbg 2.31-0ubuntu9.2 Uname: Linux 5.4.72-microsoft-standard-WSL2 x86_64 ApportVersion: 2.20.11-0ubuntu27.16 Architecture: amd64 CasperMD5CheckResult: skip Date: Sat Mar 6 22:39:51 2021 ProcEnviron: - TERM=xterm-256color - PATH=(custom, no user) - LANG=C.UTF-8 - SHELL=/bin/bash + TERM=xterm-256color + PATH=(custom, no user) + LANG=C.UTF-8 + SHELL=/bin/bash SourcePackage: glibc UpgradeStatus: No upgrade log present (probably fresh install)
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1918035 Title: ld-2.31.so is not correctly packaged in libc6-dbg To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1918035/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
