From eaebcf902ae0260b9f9b5bacdc4530c164ca114f Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Tue, 17 Jul 2018 19:00:33 +0300 Subject: [PATCH] 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: dd3bb14f44a6 ("fuse: support splice() writing to fuse device") Signed-off-by: Andrey Ryabinin Cc: # v2.6.35 Signed-off-by: Miklos Szeredi Signed-off-by: Greg Kroah-Hartman --- fs/fuse/dev.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 261fd13a75c6..f3f6cd3c2fb5 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -1941,11 +1941,14 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe, if (!fud) return -EPERM; - bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL); - if (!bufs) - return -ENOMEM; - pipe_lock(pipe); + + bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL); + if (!bufs) { + pipe_unlock(pipe); + return -ENOMEM; + } + nbuf = 0; rem = 0; for (idx = 0; idx < pipe->nrbufs && rem < len; idx++)