Re: Tracking down a segfault in delta_base_cache
Show 20 quoted lines
> On 2016-09-14, at 17:56, Jeff King <peff@peff.net> wrote:
>
> On Wed, Sep 14, 2016 at 05:42:29PM -0700, Jonathon Mah wrote:
>
>> Hi git, I've been seeing git segfault over the past few days. I'm on Mac OS X 10.12, 64-bit, compiling with clang (Apple LLVM version 8.0.0 (clang-800.0.40)).
>> [...]
>> Bisect says:
>>
>> 8261e1f139db3f8aa6f9fd7d98c876cbeb0f927c is the first bad commit
>> commit 8261e1f139db3f8aa6f9fd7d98c876cbeb0f927c
>> Author: Jeff King <peff@peff.net>
>> Date: Mon Aug 22 18:00:07 2016 -0400
>>
>> delta_base_cache: use hashmap.h
>
> Have you tried with the patch in:
>
> http://public-inbox.org/git/20160912164616.vg33kldazuthff3d@sigill.intra.peff.net/
>
> ?
All the examples I've tried work when I use that. Thanks!
Show 22 quoted lines
>> $ lldb /Users/jmah/Documents/Streams/git/git-log -- -u
>> (lldb) target create "/Users/jmah/Documents/Streams/git/git-log"
>> Current executable set to '/Users/jmah/Documents/Streams/git/git-log' (x86_64).
>> (lldb) settings set -- target.run-args "-u"
>> (lldb) process launch -o /dev/null
>> Process 92815 launched: '/Users/jmah/Documents/Streams/git/git-log' (x86_64)
>> Process 92815 stopped
>> * thread #1: tid = 0x1c30677, 0x00000001001bba80 git-log`release_delta_base_cache(ent=0xffffffffffffffd0) + 16 at sha1_file.c:2171, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x10)
>> frame #0: 0x00000001001bba80 git-log`release_delta_base_cache(ent=0xffffffffffffffd0) + 16 at sha1_file.c:2171
>> 2168
>> 2169 static inline void release_delta_base_cache(struct delta_base_cache_entry *ent)
>> 2170 {
>> -> 2171 free(ent->data);
>> 2172 detach_delta_base_cache_entry(ent);
>
> The problems I saw with valgrind weren't here, but would explain this.
> We free() the previous node, then walk forward from its "next" pointer.
> On my Linux box, that happens to work, but we could be feeding total
> junk to the list pointer, which would meant ent->data is junk, and
> free() notices.
>
> -PeffJonathon Mah <me@jonathonmah.com>