From: Jens Axboe axboe@kernel.dk
commit d5361233e9ab920e135819f73dd8466355f1fddd upstream.
io_uring tracks requests that are referencing an io_uring descriptor to be able to cancel without worrying about loops in the references. Since we now assign the file at execution time, the easier approach is to drop a potentially problematic reference before we punt the request. This eliminates the need to special case these types of files beyond just marking them as such, and simplifies cancelation quite a bit.
This also fixes a recent issue where an async punted tee operation would with the io_uring descriptor as the output file would crash when attempting to get a reference to the file from the io-wq worker. We could have worked around that, but this is the much cleaner fix.
Fixes: 6bf9c47a3989 ("io_uring: defer file assignment") Reported-by: syzbot+c4b9303500a21750b250@syzkaller.appspotmail.com Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/io_uring.c | 85 ++++++++++++++++++---------------------------------------- 1 file changed, 27 insertions(+), 58 deletions(-)
--- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -112,8 +112,7 @@ IOSQE_IO_DRAIN | IOSQE_CQE_SKIP_SUCCESS)
#define IO_REQ_CLEAN_FLAGS (REQ_F_BUFFER_SELECTED | REQ_F_NEED_CLEANUP | \ - REQ_F_POLLED | REQ_F_INFLIGHT | REQ_F_CREDS | \ - REQ_F_ASYNC_DATA) + REQ_F_POLLED | REQ_F_CREDS | REQ_F_ASYNC_DATA)
#define IO_TCTX_REFS_CACHE_NR (1U << 10)
@@ -469,7 +468,6 @@ struct io_uring_task { const struct io_ring_ctx *last; struct io_wq *io_wq; struct percpu_counter inflight; - atomic_t inflight_tracked; atomic_t in_idle;
spinlock_t task_lock; @@ -1131,6 +1129,8 @@ static void io_clean_op(struct io_kiocb static inline struct file *io_file_get_fixed(struct io_kiocb *req, int fd, unsigned issue_flags); static inline struct file *io_file_get_normal(struct io_kiocb *req, int fd); +static void io_drop_inflight_file(struct io_kiocb *req); +static bool io_assign_file(struct io_kiocb *req, unsigned int issue_flags); static void __io_queue_sqe(struct io_kiocb *req); static void io_rsrc_put_work(struct work_struct *work);
@@ -1312,29 +1312,9 @@ static bool io_match_task(struct io_kioc bool cancel_all) __must_hold(&req->ctx->timeout_lock) { - struct io_kiocb *req; - if (task && head->task != task) return false; - if (cancel_all) - return true; - - io_for_each_link(req, head) { - if (req->flags & REQ_F_INFLIGHT) - return true; - } - return false; -} - -static bool io_match_linked(struct io_kiocb *head) -{ - struct io_kiocb *req; - - io_for_each_link(req, head) { - if (req->flags & REQ_F_INFLIGHT) - return true; - } - return false; + return cancel_all; }
/* @@ -1344,24 +1324,9 @@ static bool io_match_linked(struct io_ki static bool io_match_task_safe(struct io_kiocb *head, struct task_struct *task, bool cancel_all) { - bool matched; - if (task && head->task != task) return false; - if (cancel_all) - return true; - - if (head->flags & REQ_F_LINK_TIMEOUT) { - struct io_ring_ctx *ctx = head->ctx; - - /* protect against races with linked timeouts */ - spin_lock_irq(&ctx->timeout_lock); - matched = io_match_linked(head); - spin_unlock_irq(&ctx->timeout_lock); - } else { - matched = io_match_linked(head); - } - return matched; + return cancel_all; }
static inline bool req_has_async_data(struct io_kiocb *req) @@ -1509,14 +1474,6 @@ static inline bool io_req_ffs_set(struct return req->flags & REQ_F_FIXED_FILE; }
-static inline void io_req_track_inflight(struct io_kiocb *req) -{ - if (!(req->flags & REQ_F_INFLIGHT)) { - req->flags |= REQ_F_INFLIGHT; - atomic_inc(¤t->io_uring->inflight_tracked); - } -} - static struct io_kiocb *__io_prep_linked_timeout(struct io_kiocb *req) { if (WARN_ON_ONCE(!req->link)) @@ -2380,6 +2337,8 @@ static void io_req_task_work_add(struct
WARN_ON_ONCE(!tctx);
+ io_drop_inflight_file(req); + spin_lock_irqsave(&tctx->task_lock, flags); if (priority) wq_list_add_tail(&req->io_task_work.node, &tctx->prior_task_list); @@ -5548,7 +5507,10 @@ static int io_poll_check_events(struct i if (!req->result) { struct poll_table_struct pt = { ._key = poll->events };
- req->result = vfs_poll(req->file, &pt) & poll->events; + if (unlikely(!io_assign_file(req, IO_URING_F_UNLOCKED))) + req->result = -EBADF; + else + req->result = vfs_poll(req->file, &pt) & poll->events; }
/* multishot, just fill an CQE and proceed */ @@ -6731,11 +6693,6 @@ static void io_clean_op(struct io_kiocb kfree(req->apoll); req->apoll = NULL; } - if (req->flags & REQ_F_INFLIGHT) { - struct io_uring_task *tctx = req->task->io_uring; - - atomic_dec(&tctx->inflight_tracked); - } if (req->flags & REQ_F_CREDS) put_cred(req->creds); if (req->flags & REQ_F_ASYNC_DATA) { @@ -7024,6 +6981,19 @@ out: return file; }
+/* + * Drop the file for requeue operations. Only used of req->file is the + * io_uring descriptor itself. + */ +static void io_drop_inflight_file(struct io_kiocb *req) +{ + if (unlikely(req->flags & REQ_F_INFLIGHT)) { + fput(req->file); + req->file = NULL; + req->flags &= ~REQ_F_INFLIGHT; + } +} + static struct file *io_file_get_normal(struct io_kiocb *req, int fd) { struct file *file = fget(fd); @@ -7031,8 +7001,8 @@ static struct file *io_file_get_normal(s trace_io_uring_file_get(req->ctx, fd);
/* we don't allow fixed io_uring files */ - if (file && unlikely(file->f_op == &io_uring_fops)) - io_req_track_inflight(req); + if (file && file->f_op == &io_uring_fops) + req->flags |= REQ_F_INFLIGHT; return file; }
@@ -8804,7 +8774,6 @@ static __cold int io_uring_alloc_task_co xa_init(&tctx->xa); init_waitqueue_head(&tctx->wait); atomic_set(&tctx->in_idle, 0); - atomic_set(&tctx->inflight_tracked, 0); task->io_uring = tctx; spin_lock_init(&tctx->task_lock); INIT_WQ_LIST(&tctx->task_list); @@ -9942,7 +9911,7 @@ static __cold void io_uring_clean_tctx(s static s64 tctx_inflight(struct io_uring_task *tctx, bool tracked) { if (tracked) - return atomic_read(&tctx->inflight_tracked); + return 0; return percpu_counter_sum(&tctx->inflight); }