From b782911b5297c4be0c2de88fc3b36a760eca6321 Mon Sep 17 00:00:00 2001 From: Kirill Tkhai Date: Thu, 8 Nov 2018 12:05:42 +0300 Subject: [PATCH] fuse: Verify userspace asks to requeue interrupt that we really sent When queue_interrupt() is called from fuse_dev_do_write(), it came from userspace directly. Userspace may pass any request id, even the request's we have not interrupted (or even background's request). This patch adds sanity check to make kernel safe against that. Signed-off-by: Kirill Tkhai Signed-off-by: Miklos Szeredi --- fs/fuse/dev.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c index 682c7914a0a0..ed9318d4e7dc 100644 --- a/fs/fuse/dev.c +++ b/fs/fuse/dev.c @@ -479,9 +479,15 @@ static void request_end(struct fuse_conn *fc, struct fuse_req *req) fuse_put_request(fc, req); } -static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req) +static int queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req) { spin_lock(&fiq->waitq.lock); + /* Check for we've sent request to interrupt this req */ + if (unlikely(!test_bit(FR_INTERRUPTED, &req->flags))) { + spin_unlock(&fiq->waitq.lock); + return -EINVAL; + } + if (list_empty(&req->intr_entry)) { list_add_tail(&req->intr_entry, &fiq->interrupts); /* @@ -492,12 +498,13 @@ static void queue_interrupt(struct fuse_iqueue *fiq, struct fuse_req *req) if (test_bit(FR_FINISHED, &req->flags)) { list_del_init(&req->intr_entry); spin_unlock(&fiq->waitq.lock); - return; + return 0; } wake_up_locked(&fiq->waitq); kill_fasync(&fiq->fasync, SIGIO, POLL_IN); } spin_unlock(&fiq->waitq.lock); + return 0; } static void request_wait_answer(struct fuse_conn *fc, struct fuse_req *req) @@ -1962,7 +1969,7 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud, else if (oh.error == -ENOSYS) fc->no_interrupt = 1; else if (oh.error == -EAGAIN) - queue_interrupt(&fc->iq, req); + err = queue_interrupt(&fc->iq, req); fuse_put_request(fc, req);