mainline inclusion from mainline-v7.2-rc1 commit 952b5d36f6a298f57c52a59e72076c69386a8aaf category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/16904 CVE: CVE-2026-68095 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- This fixes this race: - thread a: io_uring_enter -> register sqe -> fuse_uring_create_ring_ent -> allocate ent but doesn't grab queue_ref yet - thread b: fuse_conn_destroy() -> fuse_chan_abort() -> fuse_uring_abort() is a no-op due to queue ref being 0 - thread a: grabs the queue_ref, queue_ref is now 1, rest of fuse_uring_do_register() logic executes - thread b: fuse_chan_abort() returns, fuse_chan_wait_aborted() now runs and calls "wait_event(ring->stop_waitq, atomic_read(&ring->queue_refs) == 0);" The abort/unmount thread will hang indefinitely in unkillable state as nothing will decrement queue_refs or wake stop_waitq, and the ring, queue, and ent are leaked. Fix this by checking fch->connected under fch->lock after the created ent has grabbed a ref count on the queue. This ensures that in the scenario above, it is guaranteed that we either release the queue ref and wake up stop_waitq (in case fuse_chan_wait_aborted() is already waiting) in fuse_uring_do_register() when we detect !fch->connected, or if the connection is aborted after the check, it is guaranteed that the async teardown worker will be running in the background cleaning up ents and decrementing the ent's ref on the queue, which will unblock the eventual queue and ring teardown. Fixes: 24fe962c86f5 ("fuse: {io-uring} Handle SQEs - register commands") Cc: stable@vger.kernel.org Reviewed-by: Bernd Schubert <bernd@bsbernd.com> Signed-off-by: Joanne Koong <joannelkoong@gmail.com> Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Zhou Minqiang <zhouminqiang2@huawei.com> --- fs/fuse/dev_uring.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/fs/fuse/dev_uring.c b/fs/fuse/dev_uring.c index f4ca09ba0694..28aba59188fb 100644 --- a/fs/fuse/dev_uring.c +++ b/fs/fuse/dev_uring.c @@ -935,15 +935,26 @@ static bool is_ring_ready(struct fuse_ring *ring, int current_qid) /* * fuse_uring_req_fetch command handling */ -static void fuse_uring_do_register(struct fuse_ring_ent *ent, - struct io_uring_cmd *cmd, - unsigned int issue_flags) +static int fuse_uring_do_register(struct fuse_ring_ent *ent, + struct io_uring_cmd *cmd, + unsigned int issue_flags) { struct fuse_ring_queue *queue = ent->queue; struct fuse_ring *ring = queue->ring; struct fuse_conn *fc = ring->fc; struct fuse_iqueue *fiq = &fc->iq; + spin_lock(&fch->lock); + /* abort teardown path is running or has run */ + if (!fch->connected) { + spin_unlock(&fch->lock); + if (atomic_dec_and_test(&ring->queue_refs)) + wake_up_all(&ring->stop_waitq); + kfree(ent); + return -ECONNABORTED; + } + spin_unlock(&fch->lock); + fuse_uring_prepare_cancel(cmd, issue_flags, ent); spin_lock(&queue->lock); @@ -960,6 +971,7 @@ static void fuse_uring_do_register(struct fuse_ring_ent *ent, wake_up_all(&fc->blocked_waitq); } } + return 0; } /* @@ -1075,9 +1087,7 @@ static int fuse_uring_register(struct io_uring_cmd *cmd, if (IS_ERR(ent)) return PTR_ERR(ent); - fuse_uring_do_register(ent, cmd, issue_flags); - - return 0; + return fuse_uring_do_register(ent, cmd, issue_flags); } /* -- 2.52.0