pack-bitmap: clean up include_check after use

peff · gitster · commit 1e951c647365 · 2021-04-29T10:03:46.000+09:00
When a bitmap walk has to traverse (to fill in non-bitmapped objects),
we use rev_info's include_check mechanism to let us stop the traversal
early. But after setting the function and its data parameter, we never
clean it up. This means that if the rev_info is used for a subsequent
traversal without bitmaps, it will unexpectedly call into our
include_check function (worse, it will do so pointing to a now-defunct
stack variable in include_check_data, likely resulting in a segfault).

There's no code which does this now, but it's an accident waiting to
happen. Let's clean up after ourselves in the bitmap code.

Reported-by: David Emett &lt;dave@sp4m.net&gt;
Signed-off-by: Jeff King &lt;peff@peff.net&gt;
Signed-off-by: Junio C Hamano &lt;gitster@pobox.com&gt;
diff --git a/pack-bitmap.c b/pack-bitmap.c
@@ -630,6 +630,9 @@ static struct bitmap *find_objects(struct bitmap_index *bitmap_git,
 		traverse_commit_list_filtered(filter, revs,
 					      show_commit, show_object,
 					      &show_data, NULL);
+
+		revs->include_check = NULL;
+		revs->include_check_data = NULL;
 	}
 
 	return base;

Original file line number	Diff line number	Diff line change
`@@ -630,6 +630,9 @@ static struct bitmap find_objects(struct bitmap_index bitmap_git,`
`630`	`630`	`traverse_commit_list_filtered(filter, revs,`
`631`	`631`	`show_commit, show_object,`
`632`	`632`	`&show_data, NULL);`
	`633`	`+`
	`634`	`+ revs->include_check = NULL;`
	`635`	`+ revs->include_check_data = NULL;`
`633`	`636`	`}`
`634`	`637`
`635`	`638`	`return base;`