Commit 67a9e487 authored Jul 17, 2018 by Andrey Ryabinin Committed by Greg Kroah-Hartman Sep 05, 2018

fuse: Don't access pipe->buffers without pipe_lock()



commit a2477b0e67c52f4364a47c3ad70902bc2a61bd4c upstream.

fuse_dev_splice_write() reads pipe->buffers to determine the size of
'bufs' array before taking the pipe_lock(). This is not safe as
another thread might change the 'pipe->buffers' between the allocation
and taking the pipe_lock(). So we end up with too small 'bufs' array.

Move the bufs allocations inside pipe_lock()/pipe_unlock() to fix this.

Fixes: dd3bb14f ("fuse: support splice() writing to fuse device")
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: <stable@vger.kernel.org> # v2.6.35
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 6a2346f3

fs/fuse/dev.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -1935,11 +1935,14 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
		if (!fud)
		return -EPERM;

		pipe_lock(pipe);

		bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
		if (!bufs)
		if (!bufs) {
		pipe_unlock(pipe);
		return -ENOMEM;
		}

		pipe_lock(pipe);
		nbuf = 0;
		rem = 0;
		for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)