Hi,
Certain invalid input causes git rev-parse to crash rather
than return a 'fatal: ambiguous argument ...' error.
This was reported against the Fedora git package:
https://bugzilla.redhat.com/1581678
Simple reproduction recipe and analysis, from the bug:
$ git init
Initialized empty Git repository in /tmp/t/.git/
$ git rev-parse ffffffffffffffffffffffffffffffffffffffff^@
Segmentation fault (core dumped)
gdb) break lookup_commit_reference
Breakpoint 1 at 0x555555609f00: lookup_commit_reference. (3 locations)
(gdb) r
Starting program: /usr/bin/git rev-parse ffffffffffffffffffffffffffffffffffffffff\^@
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
Breakpoint 1, lookup_commit_reference (oid=oid@entry=0x7fffffffd550) at commit.c:34
34 return lookup_commit_reference_gently(oid, 0);
(gdb) finish
Run till exit from #0 lookup_commit_reference (oid=oid@entry=0x7fffffffd550) at commit.c:34
try_parent_shorthands (arg=0x7fffffffdd44 'f' <repeats 40 times>) at builtin/rev-parse.c:314
314 include_parents = 1;
Value returned is $1 = (struct commit *) 0x0
(gdb) c
(gdb) c
Continuing.
Program received signal SIGSEGV, Segmentation fault.
try_parent_shorthands (arg=0x7fffffffdd44 'f' <repeats 40 times>) at builtin/rev-parse.c:345
345 for (parents = commit->parents, parent_number = 1;
(gdb) l 336,+15
336 commit = lookup_commit_reference(&oid);
337 if (exclude_parent &&
338 exclude_parent > commit_list_count(commit->parents)) {
339 *dotdot = '^';
340 return 0;
341 }
342
343 if (include_rev)
344 show_rev(NORMAL, &oid, arg);
345 for (parents = commit->parents, parent_number = 1;
346 parents;
347 parents = parents->next, parent_number++) {
348 char *name = NULL;
349
350 if (exclude_parent && parent_number != exclude_parent)
351 continue;
Looks like a null pointer check is missing.
This occurs on master and as far back as 1.8.3.1 (what's in
RHEL-6, I didn't try to test anything older). Only a string
with 40 valid hex characters and ^@, @-, of ^! seems to
trigger it.
--
Todd
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
I don't mind arguing with myself. It's when I lose that it bothers me.
-- Richard Powers
