Re: git svn 2.26.0 segfault on fetch

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Mar 27, 2020, 21:26 UTC
Message-ID: <20200327212656.GM6499@camp.crustytoothpaste.net>
In-Reply-To: <CAAr69zbzX=ihOQLZRELWHaC42vs=XtNGkuJ+WhzeWaokPNcfAA@mail.gmail.com>

On 2020-03-27 at 16:36:56, Szőts Ákos wrote:

Show 10 quoted lines

> Dear list,
> 
> When I use a "git svn fetch" on my git-SVN repository it dies with
> "error: git-svn died of signal 11".
> 
> I tried to get a coredump or attach GDB to it but as I see in strace
> there are signal handlers attached to INT, HUP, TERM, QUIT, and PIPE
> and possibly because of them no coredumps are generated even with
> unlimited "-c" and also possibly because of this GDB doesn't stop on
> SIGSEGV.

Git uses the Subversion Perl bindings and git-svn is written entirely in Perl. While it's possible we've broken something, it's probably a little more likely that the Subversion Perl bindings on your system are a little broken and that's what's causing the issue.

What operating system are you using?

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> What I could do still with turned off ASLR is to run Valgrind with
> children tracking. It gave the following results:
> 
> Warning: invalid file descriptor -1 in syscall close()
> Invalid read of size 4
>    at 0x9B1A82C: UnknownInlinedFun (atomic_base.h:419)
>    by 0x9B1A82C: UnknownInlinedFun (qatomic_cxx11.h:239)
>    by 0x9B1A82C: UnknownInlinedFun (qbasicatomic.h:107)
>    by 0x9B1A82C: UnknownInlinedFun (qrefcount.h:66)
>    by 0x9B1A82C: UnknownInlinedFun (qstring.h:1263)
>    by 0x9B1A82C: UnknownInlinedFun (kaboutdata.cpp:460)
>    by 0x9B1A82C: KAboutData::~KAboutData() (kaboutdata.cpp:583)
>    by 0x9B1AADC: (anonymous
> namespace)::Q_QGS_s_registry::innerFunction()::Holder::~Holder()
> (kaboutdata.cpp:1041)
>    by 0x4A63706: __run_exit_handlers (exit.c:108)
>    by 0x4A638BB: exit (exit.c:139)
>    by 0x154465: main (perlmain.c:171)
>  Address 0x80cf1c0 is not stack'd, malloc'd or (recently) free'd

This looks like you're loading something with Qt. Are you using the Subversion KWallet integration? Does disabling it make things work?

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> Process terminating with default action of signal 11 (SIGSEGV): dumping core
>  Access not within mapped region at address 0x80CF1C0
>    at 0x9B1A82C: UnknownInlinedFun (atomic_base.h:419)
>    by 0x9B1A82C: UnknownInlinedFun (qatomic_cxx11.h:239)
>    by 0x9B1A82C: UnknownInlinedFun (qbasicatomic.h:107)
>    by 0x9B1A82C: UnknownInlinedFun (qrefcount.h:66)
>    by 0x9B1A82C: UnknownInlinedFun (qstring.h:1263)
>    by 0x9B1A82C: UnknownInlinedFun (kaboutdata.cpp:460)
>    by 0x9B1A82C: KAboutData::~KAboutData() (kaboutdata.cpp:583)
>    by 0x9B1AADC: (anonymous
> namespace)::Q_QGS_s_registry::innerFunction()::Holder::~Holder()
> (kaboutdata.cpp:1041)
>    by 0x4A63706: __run_exit_handlers (exit.c:108)
>    by 0x4A638BB: exit (exit.c:139)
>    by 0x154465: main (perlmain.c:171)
>  If you believe this happened as a result of a stack
>  overflow in your program's main thread (unlikely but
>  possible), you can try to increase the size of the
>  main thread stack using the --main-stacksize= flag.
>  The main thread stack size used in this run was 8388608.
> 
> During stracing I found this line around the SIGSEGV:
> close(-1)                   = -1 EBADF
> 
> If you could tell me how it's possible to attach GDB onto it, I'd be
> glad to provide you some backtraces as well.

You'd need to run something like the following:

  gdb --args /usr/bin/perl /usr/lib/git-core/git-svn <ARGS>

Note that I don't use git-svn and remember next to nothing about using Subversion, so hopefully any information you provide makes sense to someone more familiar with git-svn than I.

-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204