[Outreachy] [PATCH v3] bisect--helper: avoid use-after-free

[Miriam Rubio <mirucam@gmail.com>]

From: Tanushree Tumane <tanushreetumane@gmail.com>

In 5e82c3dd22a (bisect--helper: `bisect_reset` shell function in C,
2019-01-02), the `git bisect reset` subcommand was ported to C. When the
call to `git checkout` failed, an error message was reported to the
user.

However, this error message used the `strbuf` that had just been
released already. Let's switch that around: first use it, then release
it.

Mentored-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Tanushree Tumane <tanushreetumane@gmail.com>
Signed-off-by: Miriam Rubio <mirucam@gmail.com>
Acked-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
This patch is a new version of
https://public-inbox.org/git/20191209103923.21659-1-mirucam@gmail.com/
which itself has been sent previously by Tanushree
(https://public-inbox.org/git/64117cde718f0d56ebfa4c30f4d8fe2155f5cf65.1551003074.git.gitgitgadget@gmail.com/).

 builtin/bisect--helper.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/builtin/bisect--helper.c b/builtin/bisect--helper.c
index 1fbe156e67..3055b2bb50 100644
--- a/builtin/bisect--helper.c
+++ b/builtin/bisect--helper.c
@@ -169,11 +169,12 @@ static int bisect_reset(const char *commit)
 
 		argv_array_pushl(&argv, "checkout", branch.buf, "--", NULL);
 		if (run_command_v_opt(argv.argv, RUN_GIT_CMD)) {
+			error(_("could not check out original"
+				" HEAD '%s'. Try 'git bisect"
+				" reset <commit>'."), branch.buf);
 			strbuf_release(&branch);
 			argv_array_clear(&argv);
-			return error(_("could not check out original"
-				       " HEAD '%s'. Try 'git bisect"
-				       " reset <commit>'."), branch.buf);
+			return -1;
 		}
 		argv_array_clear(&argv);
 	}
-- 
2.21.0 (Apple Git-122.2)