[PATCH] fsck: check results of lookup_blob() and lookup_tree() for NULL

["René Scharfe" <l.s.r@web.de>]

Am 03.10.2017 um 14:51 schrieb René Scharfe:
> Am 03.10.2017 um 12:22 schrieb SZEDER Gábor:
>> Furthermore, fsck.c:fsck_walk_tree() does the same "immediately
>> reference the object member in lookup_blob()'s and lookup_tree()'s
>> return value" thing.  I think those should receive the same treatment
>> as well.
> 
> Hmm, are put_object_name() and all the walk() implementations ready for
> a NULL object handed to them?  Or would we rather need to error out
> right there?
How about this?

-- >8 --
lookup_blob() and lookup_tree() can return NULL if they find an object
of an unexpected type.  Error out of fsck_walk_tree() in that case, like
we do when encountering a bad file mode.  An error message is already
shown by object_as_type(), which gets called by the lookup functions.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
---
 fsck.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/fsck.c b/fsck.c
index 2ad00fc4d0..561a13ac27 100644
--- a/fsck.c
+++ b/fsck.c
@@ -358,14 +358,20 @@ static int fsck_walk_tree(struct tree *tree, void *data, struct fsck_options *op
 			continue;
 
 		if (S_ISDIR(entry.mode)) {
-			obj = &lookup_tree(entry.oid)->object;
+			struct tree *tree = lookup_tree(entry.oid);
+			if (!tree)
+				return -1;
+			obj = &tree->object;
 			if (name)
 				put_object_name(options, obj, "%s%s/", name,
 					entry.path);
 			result = options->walk(obj, OBJ_TREE, data, options);
 		}
 		else if (S_ISREG(entry.mode) || S_ISLNK(entry.mode)) {
-			obj = &lookup_blob(entry.oid)->object;
+			struct blob *blob = lookup_blob(entry.oid);
+			if (!blob)
+				return -1;
+			obj = &blob->object;
 			if (name)
 				put_object_name(options, obj, "%s%s", name,
 					entry.path);
-- 
2.14.2