[34-longterm 171/179] fuse: check size of FUSE_NOTIFY_INVAL_ENTRY message

[Paul Gortmaker]

From: Miklos Szeredi <mszeredi@xxxxxxx>

                   -------------------
    This is a commit scheduled for the next v2.6.34 longterm release.
    http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
    If you see a problem with using this for longterm, please comment.
                   -------------------

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@xxxxxxxxx>
Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxx>
Signed-off-by: Paul Gortmaker <paul.gortmaker@xxxxxxxxxxxxx>
---
 fs/fuse/dev.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
index c235afc..9897fe3 100644
--- 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);
-- 
1.7.9.6

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