fuse: check size of FUSE_NOTIFY_INVAL_ENTRY message

FUSE_NOTIFY_INVAL_ENTRY didn't check the length of the write so the
message processing could overrun and result in a "kernel BUG at
fs/fuse/dev.c:629!"

Reported-by: Han-Wen Nienhuys <hanwenn@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org

1 files changed, 4 insertions, 0 deletions

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index 640fc229df10..168a80f7f12b 100644
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -1358,6 +1358,10 @@ static int fuse_notify_inval_entry(struct fuse_conn *fc, unsigned int size,
         if (outarg.namelen > FUSE_NAME_MAX)
                 goto err;
 
+        err = -EINVAL;
+        if (size != sizeof(outarg) + outarg.namelen + 1)
+                goto err;
+
         name.name = buf;
         name.len = outarg.namelen;
         err = fuse_copy_one(cs, buf, outarg.namelen + 1);