[PATCH AUTOSEL 5.15 18/23] udf: Fix uninitialized array access for some pathnames

[Sasha Levin]

From: Jan Kara <jack@xxxxxxx>

[ Upstream commit 028f6055c912588e6f72722d89c30b401bbcf013 ]

For filenames that begin with . and are between 2 and 5 characters long,
UDF charset conversion code would read uninitialized memory in the
output buffer. The only practical impact is that the name may be prepended a
"unification hash" when it is not actually needed but still it is good
to fix this.

Reported-by: syzbot+cd311b1e43cc25f90d18@xxxxxxxxxxxxxxxxxxxxxxxxx
Link: https://lore.kernel.org/all/000000000000e2638a05fe9dc8f9@xxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 fs/udf/unicode.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/udf/unicode.c b/fs/udf/unicode.c
index 622569007b530..2142cbd1dde24 100644
--- a/fs/udf/unicode.c
+++ b/fs/udf/unicode.c
@@ -247,7 +247,7 @@ static int udf_name_from_CS0(struct super_block *sb,
 	}
 
 	if (translate) {
-		if (str_o_len <= 2 && str_o[0] == '.' &&
+		if (str_o_len > 0 && str_o_len <= 2 && str_o[0] == '.' &&
 		    (str_o_len == 1 || str_o[1] == '.'))
 			needsCRC = 1;
 		if (needsCRC) {
-- 
2.39.2