git-update-server-info crashes on hera.kernel.org:/pub/scm/libs/klibc/klibc.git

git-update-server-info crashes on hera.kernel.org:/pub/scm/libs/klibc/klibc.git

[H. Peter Anvin]

git-core-0.99.9j-1, and the backtrace is as follows:

: hera 29 ; ls -l /usr/lib/debug/usr/bin/git-update-
git-update-index.debug*       git-update-ref.debug* 
git-update-server-info.debug*
: hera 29 ; gdb -s /usr/lib/debug/usr/bin/git-update-server-info.debug 
/usr/bin/git-update-server-info
GNU gdb Red Hat Linux (6.3.0.0-1.63rh)
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain 
conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-redhat-linux-gnu"...Using host 
libthread_db library "/lib/tls/libthread_db.so.1".

(gdb) run
Starting program: /usr/bin/git-update-server-info

Program received signal SIGSEGV, Segmentation fault.
0x0804c04c in nth_packed_object_sha1 (p=0x986a1f0, n=0, sha1=0xbfffc9f0 
"") at sha1_file.c:1017
1017            memcpy(sha1, (index + 24 * n + 4), 20);
(gdb) where
#0  0x0804c04c in nth_packed_object_sha1 (p=0x986a1f0, n=0, 
sha1=0xbfffc9f0 "") at sha1_file.c:1017
#1  0x08049a61 in update_server_info (force=0) at server-info.c:248
#2  0x08049466 in main (ac=1, av=0xbfffeed4) at update-server-info.c:22
#3  0x00ce1e23 in __libc_start_main () from /lib/tls/libc.so.6
#4  0x080493a1 in _start ()

	-hpa

Re: git-update-server-info crashes on hera.kernel.org:/pub/scm/libs/klibc/klibc.git

[Junio C Hamano]

I made a copy of that repository on hera and tried it but cannot
reproduce (with or without -f flag -- and running under gdb with
symbols did not make difference either).  Sorry, I am baffled.
The same machine, the same set of input and binary.

junio@hera:~/t(0)$ echo $PATH
/usr/kerberos/bin:/usr/local/bin:/bin:/usr/bin:/usr/X11R6/bin
junio@hera:~/t(0)$ (cd /pub/scm/libs/klibc/ && tar cf - klibc.git ) | tar xf -
junio@hera:~/t(0)$ head -n 4 klibc.git/objects/info/packs
P pack-122eb314270865bdaaded7d02c7340014537abbf.pack
D 0
T 0 005146812e1e36309409128e0bbaf86e6745a637 tag
T 0 00aea41acad6d139679416a79ff9139a50b5001c tag
junio@hera:~/t(0)$ GIT_DIR=klibc.git /usr/bin/git-update-server-info ; echo $?
0
junio@hera:~/t(0)$ head -n 4 klibc.git/objects/info/packs
P pack-1433c87e76496ad3f628652c0cb81d288c178fc5.pack
P pack-f9db0b232716d835858232fbecfb410d22ae5afb.pack
D 0
junio@hera:~/t(0)$ rm -fr klibc.git
junio@hera:~/t(0)$ (cd /pub/scm/libs/klibc/ && tar cf - klibc.git ) | tar xf -  junio@hera:~/t(0)$ head -n 4 klibc.git/objects/info/packs
P pack-122eb314270865bdaaded7d02c7340014537abbf.pack
D 0
T 0 005146812e1e36309409128e0bbaf86e6745a637 tag
T 0 00aea41acad6d139679416a79ff9139a50b5001c tag
junio@hera:~/t(0)$ GIT_DIR=klibc.git /usr/bin/git-update-server-info -f; echo $?
0
junio@hera:~/t(0)$ head -n 4 klibc.git/objects/info/packs
P pack-122eb314270865bdaaded7d02c7340014537abbf.pack
P pack-1433c87e76496ad3f628652c0cb81d288c178fc5.pack
P pack-f9db0b232716d835858232fbecfb410d22ae5afb.pack
D 0
junio@hera:~/t(0)$ exit

Re: git-update-server-info crashes on hera.kernel.org:/pub/scm/libs/klibc/klibc.git

[H. Peter Anvin]

Junio C Hamano wrote:
> I made a copy of that repository on hera and tried it but cannot
> reproduce (with or without -f flag -- and running under gdb with
> symbols did not make difference either).  Sorry, I am baffled.
> The same machine, the same set of input and binary.
> 

FWIW, I invoked this as:

hpa@hera:~(0)$ GIT_DIR=/pub/scm/libs/klibc/klibc.git git-update-server-info
Segmentation fault

	-hpa

Re: git-update-server-info crashes on hera.kernel.org:/pub/scm/libs/klibc/klibc.git

[Junio C Hamano]

"H. Peter Anvin" <hpa@zytor.com> writes:

> FWIW, I invoked this as:
>
> hpa@hera:~(0)$ GIT_DIR=/pub/scm/libs/klibc/klibc.git git-update-server-info
> Segmentation fault

Trusting that I *won't* be able to write into that repository, I
tried to run that and after getting an error ("cannot update
info/refs file", which I wanted to see) I seem to be getting the
same segfault.  GDB session reveals the binary is heavily
optimized or inlined, so it is hard to see what it is doing
though.

But there is one thing that is mysterious about your repository,
and by mirroring that peculiarity with the copy in my home
directory, I managed to reproduce the problem with my copy.  Why
does the objects/info/alternates in that repository point at
itself?  I suspect if you remove that file you will be OK.

update-server-info simply dying, instead of complaining about
it, is a bug nevertheless, and removal of the
unnecessary/possibly wrong alternate is only a workaround, but I
hope that would unblock you in the meantime..

Re: git-update-server-info crashes on hera.kernel.org:/pub/scm/libs/klibc/klibc.git

[H. Peter Anvin]

Junio C Hamano wrote:
> "H. Peter Anvin" <hpa@zytor.com> writes:
> 
> 
>>FWIW, I invoked this as:
>>
>>hpa@hera:~(0)$ GIT_DIR=/pub/scm/libs/klibc/klibc.git git-update-server-info
>>Segmentation fault
> 
> 
> Trusting that I *won't* be able to write into that repository, I
> tried to run that and after getting an error ("cannot update
> info/refs file", which I wanted to see) I seem to be getting the
> same segfault.  GDB session reveals the binary is heavily
> optimized or inlined, so it is hard to see what it is doing
> though.
> 
> But there is one thing that is mysterious about your repository,
> and by mirroring that peculiarity with the copy in my home
> directory, I managed to reproduce the problem with my copy.  Why
> does the objects/info/alternates in that repository point at
> itself?  I suspect if you remove that file you will be OK.
> 
> update-server-info simply dying, instead of complaining about
> it, is a bug nevertheless, and removal of the
> unnecessary/possibly wrong alternate is only a workaround, but I
> hope that would unblock you in the meantime..
> 

Removing that file did indeed work.  I have no idea where it comes from, 
though; although I would guess it comes from another repository that I 
merged with (which had my original repository set as an alternate.)

	-hpa