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Re: [PATCH 2/2] worktree: reject empty string

From
René Scharfe <l.s.r@web.de>
Date
Aug 2, 2026, 09:58 UTC
Message-ID
<077f11be-489f-4174-adbc-82a610137a41@web.de>
In-Reply-To
<f6b7af1a-29fd-4bec-b819-34b7962180fb@web.de>
On 8/2/26 8:26 AM, René Scharfe wrote:
Show 35 quoted lines
> On 7/25/26 1:19 PM, Matthias AÃhauer via GitGitGadget wrote:
>> From: =?UTF-8?q?Matthias=20A=C3=9Fhauer?= <mha1993@live.de>
>>
>> `git worktree add ""` errors out with the message `BUG: How come ''
>> becomes empty after sanitization?`, but not due to a bug in the
>> sanitization code. An empty string should remain empty during
>> sanitization. Instead reject the argument as invalid user input,
>> if it's already empty before sanitization.
>>
>> Signed-off-by: Matthias Aßhauer <mha1993@live.de>
>> ---
>>  builtin/worktree.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/builtin/worktree.c b/builtin/worktree.c
>> index d8188035db..113dbf98d3 100644
>> --- a/builtin/worktree.c
>> +++ b/builtin/worktree.c
>> @@ -496,6 +496,8 @@ static int add_worktree(const char *path, const char *refname,
>>  		die(_("invalid reference: %s"), refname);
>>  
>>  	name = worktree_basename(path, &len);
>> +	if (!len)
>> +		die(_("the empty string is not a valid worktree"));
>>  	strbuf_add(&sb, name, path + len - name);
>>  	sanitize_refname_component(sb.buf, &sb_name);
>>  	if (!sb_name.len)
> 
> Hmm, on my machine, with or without this patch:
> 
>    $ git worktree add ""
>    Preparing worktree (new branch '')
>    fatal: '' is not a valid branch name
>    hint: See 'git help check-ref-format'
>    hint: Disable this message with "git config set advice.refSyntax false"
This hits the BUG by passing the empty string directly to add_worktree():
   $ git worktree add "" HEAD
   Preparing worktree (detached HEAD a97fcc37c2)
   BUG: builtin/worktree.c:498: How come '' becomes empty after sanitization?
René
Previous: René ScharfeNext: René Scharfe
Message 7 of 11 in “worktree: Fix out of bounds read that causes data loss and reject invalid empty input in worktree add”
  1. 0/2 worktree: Fix out of bounds read that causes data loss and reject invalid empty input in worktree addMatthias Aßhauer via GitGitGadget, Jul 25, 2026
  2. 1/2 worktree: don't read out of boundsMatthias Aßhauer via GitGitGadget, Jul 25, 2026
  3. Junio C HamanoJul 25, 2026
  4. René ScharfeJul 31, 2026
  5. 2/2 worktree: reject empty stringMatthias Aßhauer via GitGitGadget, Jul 25, 2026
  6. René ScharfeAug 2, 2026
  7. René ScharfeAug 2, 2026
  8. worktree: Fix out of bounds read that causes data loss and reject invalid empty input in worktree addRené Scharfe, Aug 11, 2026
  9. Junio C HamanoAug 11, 2026
  10. René ScharfeAug 16, 2026
  11. Junio C HamanoAug 16, 2026

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