[PATCH] sequencer: fix memory leak if `update_squash_messages()` failed

From: Lidong Yan via GitGitGadget <gitgitgadget@gmail.com>
Date: May 14, 2025, 12:44 UTC
Message-ID: <pull.1964.git.git.1747226641249.gitgitgadget@gmail.com>

From: Lidong Yan <502024330056@smail.nju.edu.cn>

In sequencer.c:update_squash_messages, `repo_logmsg_reencode` returns either an allocated reencode string or commit buffer if no encode is needed. To free `repo_logmsg_reencode` result, `repo_unuse_commit_buffer` should be used. However, when encountering the error("unknown command..."), the absence of `repo_unuse_commit_buffer` results in a memory leak. I think we should add a `repo_unuse_commit_buffer` before return.

Signed-off-by: Lidong Yan <502024330056@smail.nju.edu.cn>
---
    sequencer: fix memory leak if update_squash_messages() failed
    
    In sequencer.c:update_squash_messages, repo_logmsg_reencode returns
    either an allocated reencode string or commit buffer if no encode is
    needed. To free repo_logmsg_reencode result, repo_unuse_commit_buffer
    should be used. However, when encountering the error("unknown
    command..."), the absence of repo_unuse_commit_buffer results in a
    memory leak. I think we should add a repo_unuse_commit_buffer before
    return.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1964%2Fbrandb97%2Ffix-sequencer-leak-v1
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1964/brandb97/fix-sequencer-leak-v1
Pull-Request: https://github.com/git/git/pull/1964

 sequencer.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/sequencer.c b/sequencer.c
index b5c4043757e..f288a303eaa 100644
--- a/sequencer.c
+++ b/sequencer.c
@@ -2138,8 +2138,10 @@ static int update_squash_messages(struct repository *r,
 		strbuf_addstr(&buf, "\n\n");
 		strbuf_add_commented_lines(&buf, body, strlen(body),
 					   comment_line_str);
-	} else
+	} else {
+		repo_unuse_commit_buffer(r, commit, message);
 		return error(_("unknown command: %d"), command);
+	}
 	repo_unuse_commit_buffer(r, commit, message);
 
 	if (!res)

base-commit: 6f84262c44a89851c3ae5a6e4c1a9d06b2068d75

-- 
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