fuse: check size of FUSE_NOTIFY_INVAL_ENTRY message

commit c2183d1e9b3f313dd8ba2b1b0197c8d9fb86a7ae upstream.

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>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c235afc698a0d8f47553cc409a4b6b9c01d35350..9897fe3388185c7535fe63a3c2eb865bf69f05cd 100644 (file)
--- a/fs/fuse/dev.c
+++ b/fs/fuse/dev.c
@@ -901,6 +901,10 @@ 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);