[PATCH 3/6] revert: Fix buffer overflow in insn sheet parser

[Ramkumar Ramachandra <artagnon@gmail.com>]

Check that the commit name argument to a "pick" or "revert" action in
'.git/sequencer/todo' is not too long, to avoid overflowing an
on-stack buffer.  This fixes a regression introduced by 5a5d80f4
(revert: Introduce --continue to continue the operation, 2011-08-04).

Reported-by: Jonathan Nieder <jrnieder@gmail.com>
Acked-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
---
 builtin/revert.c                |    2 +-
 t/t3510-cherry-pick-sequence.sh |   14 ++++++++++++++
 2 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/builtin/revert.c b/builtin/revert.c
index b3c5e0e..6451089 100644
--- a/builtin/revert.c
+++ b/builtin/revert.c
@@ -707,7 +707,7 @@ static struct commit *parse_insn_line(char *start, struct replay_opts *opts)
 		return NULL;
 
 	q = strchr(p, ' ');
-	if (!q)
+	if (!q || q - p + 1 > sizeof(sha1_abbrev))
 		return NULL;
 	q++;
 
diff --git a/t/t3510-cherry-pick-sequence.sh b/t/t3510-cherry-pick-sequence.sh
index 3bca2b3..2113308 100755
--- a/t/t3510-cherry-pick-sequence.sh
+++ b/t/t3510-cherry-pick-sequence.sh
@@ -12,6 +12,9 @@ test_description='Test cherry-pick continuation features
 
 . ./test-lib.sh
 
+# Repeat first match 10 times
+_r10='\1\1\1\1\1\1\1\1\1\1'
+
 pristine_detach () {
 	git cherry-pick --reset &&
 	git checkout -f "$1^0" &&
@@ -211,4 +214,15 @@ test_expect_success 'malformed instruction sheet 2' '
 	test_must_fail git cherry-pick --continue
 '
 
+test_expect_success 'malformed instruction sheet 3' '
+	pristine_detach initial &&
+	test_must_fail git cherry-pick base..anotherpick &&
+	echo "resolved" >foo &&
+	git add foo &&
+	git commit &&
+	sed "s/pick \([0-9a-f]*\)/pick $_r10/" .git/sequencer/todo >new_sheet &&
+	cp new_sheet .git/sequencer/todo &&
+	test_must_fail git cherry-pick --continue
+'
+
 test_done
-- 
1.7.4.1