Regression in v2.23

Hello,

With git 2.23.0 I have:

	uwe@taurus:~/tmp/rangediff-segfault$ git init
	Initialized empty Git repository in /home/uwe/tmp/rangediff-segfault/.git/
	uwe@taurus:~/tmp/rangediff-segfault$ echo root > root
	uwe@taurus:~/tmp/rangediff-segfault$ git add root
	uwe@taurus:~/tmp/rangediff-segfault$ git commit -m root
	[master (root-commit) b0feddb2dee8] root
	 1 file changed, 1 insertion(+)
	 create mode 100644 root
	uwe@taurus:~/tmp/rangediff-segfault$ echo content > file
	uwe@taurus:~/tmp/rangediff-segfault$ chmod +x file
	uwe@taurus:~/tmp/rangediff-segfault$ git add file
	uwe@taurus:~/tmp/rangediff-segfault$ git commit -m file
	[master 45b547c57acd] file
	 1 file changed, 1 insertion(+)
	 create mode 100755 file
	uwe@taurus:~/tmp/rangediff-segfault$ chmod -x file
	uwe@taurus:~/tmp/rangediff-segfault$ git add file
	uwe@taurus:~/tmp/rangediff-segfault$ git commit -m 'chmod -x'
	[master eaa5d3b98caa] chmod -x
	 1 file changed, 0 insertions(+), 0 deletions(-)
	 mode change 100755 => 100644 file
	uwe@taurus:~/tmp/rangediff-segfault$ git range-diff @~2..@~ @~2..
	Segmentation fault (core dumped)

Bisecting points to b66885a30cb84fc61986bc4eea805a31fdbea79a, current master (b744c3af07a15aaeb1b82fab689995fd5528f120) segfaults in the same way.

This is somehow similar to https://public-inbox.org/git/20190923101929.GA18205@kitsune.suse.cz/ but the patch by Johannes Schindelin sent in https://public-inbox.org/git/pull.373.git.gitgitgadget@gmail.com/ doesn't help me.

For me the segfault also happens in

	strbuf_addstr(&buf, patch.new_name);

with patch.new_name being NULL.

The matching backtrace and patch object looks as follows:

	(gdb) bt
	#0  __strlen_avx2 () at ../sysdeps/x86_64/multiarch/strlen-avx2.S:65
	#1  0x0000555cc448949c in strbuf_addstr (s=<optimized out>, sb=0x7ffcd1d9ef00)
	    at strbuf.h:292
	#2  read_patches (range=range@entry=0x555cc5dc2b70 "@~2..", 
	    list=list@entry=0x7ffcd1d9f280) at range-diff.c:126
	#3  0x0000555cc44898a8 in show_range_diff (range1=0x555cc5dc2b50 "@~2..@~", 
	    range2=0x555cc5dc2b70 "@~2..", creation_factor=60, dual_color=1, 
	    diffopt=diffopt@entry=0x7ffcd1d9f680) at range-diff.c:507
	#4  0x0000555cc4397aa6 in cmd_range_diff (argc=<optimized out>, 
	    argv=<optimized out>, prefix=<optimized out>) at builtin/range-diff.c:80
	#5  0x0000555cc4328494 in run_builtin (argv=<optimized out>, 
	    argc=<optimized out>, p=<optimized out>) at git.c:445
	#6  handle_builtin (argc=<optimized out>, argv=<optimized out>) at git.c:674
	#7  0x0000555cc4329554 in run_argv (argv=0x7ffcd1d9f9e0, argcp=0x7ffcd1d9f9ec)
	    at git.c:741
	#8  cmd_main (argc=<optimized out>, argv=<optimized out>) at git.c:872
	#9  0x0000555cc432803a in main (argc=4, argv=0x7ffcd1d9fc78)
	    at common-main.c:52
	(gdb) up 2
	#2  read_patches (range=range@entry=0x555cc5dc2b70 "@~2..", 
	    list=list@entry=0x7ffcd1d9f280) at range-diff.c:126
	126	range-diff.c: No such file or directory.
	(gdb) print patch
	$1 = {new_name = 0x0, old_name = 0x0, def_name = 0x555cc5dc98c0 "file", 
	  old_mode = 33261, new_mode = 33188, is_new = 0, is_delete = 0, rejected = 0, 
	  ws_rule = 0, lines_added = 0, lines_deleted = 0, score = 0, 
	  extension_linenr = 0, is_toplevel_relative = 0, inaccurate_eof = 0, 
	  is_binary = 0, is_copy = 0, is_rename = 0, recount = 0, 
	  conflicted_threeway = 0, direct_to_threeway = 0, crlf_in_old = 0, 
	  fragments = 0x0, result = 0x0, resultsize = 0, 
	  old_oid_prefix = '\000' <repeats 64 times>, 
	  new_oid_prefix = '\000' <repeats 64 times>, next = 0x0, threeway_stage = {{
	      hash = '\000' <repeats 31 times>}, {hash = '\000' <repeats 31 times>}, {
	      hash = '\000' <repeats 31 times>}}}

I guess you are able to work out the details with this information. If you need more input, please Cc: me on replies.

Best regards Uwe