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author | Jens Axboe <axboe@kernel.dk> | 2023-11-28 10:29:58 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-01-20 11:51:38 +0100 |
commit | 0c7df8c241ff066b19782100f6bfc288144d7a38 (patch) | |
tree | 5c40d3c80f233f010538a704d1cf59c1c0e93c00 | |
parent | 75cc56afb28b0f113f79d8906f7fed9100cea288 (diff) | |
download | linux-stable-0c7df8c241ff066b19782100f6bfc288144d7a38.tar.gz linux-stable-0c7df8c241ff066b19782100f6bfc288144d7a38.tar.bz2 linux-stable-0c7df8c241ff066b19782100f6bfc288144d7a38.zip |
io_uring: use fget/fput consistently
[ Upstream commit 73363c262d6a7d26063da96610f61baf69a70f7c ]
Normally within a syscall it's fine to use fdget/fdput for grabbing a
file from the file table, and it's fine within io_uring as well. We do
that via io_uring_enter(2), io_uring_register(2), and then also for
cancel which is invoked from the latter. io_uring cannot close its own
file descriptors as that is explicitly rejected, and for the cancel
side of things, the file itself is just used as a lookup cookie.
However, it is more prudent to ensure that full references are always
grabbed. For anything threaded, either explicitly in the application
itself or through use of the io-wq worker threads, this is what happens
anyway. Generalize it and use fget/fput throughout.
Also see the below link for more details.
Link: https://lore.kernel.org/io-uring/CAG48ez1htVSO3TqmrF8QcX2WFuYTRM-VZ_N10i-VZgbtg=NNqw@mail.gmail.com/
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
-rw-r--r-- | io_uring/cancel.c | 11 | ||||
-rw-r--r-- | io_uring/io_uring.c | 36 |
2 files changed, 24 insertions, 23 deletions
diff --git a/io_uring/cancel.c b/io_uring/cancel.c index 7b23607cf4af..a5d51471feeb 100644 --- a/io_uring/cancel.c +++ b/io_uring/cancel.c @@ -263,7 +263,7 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg) }; ktime_t timeout = KTIME_MAX; struct io_uring_sync_cancel_reg sc; - struct fd f = { }; + struct file *file = NULL; DEFINE_WAIT(wait); int ret, i; @@ -285,10 +285,10 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg) /* we can grab a normal file descriptor upfront */ if ((cd.flags & IORING_ASYNC_CANCEL_FD) && !(cd.flags & IORING_ASYNC_CANCEL_FD_FIXED)) { - f = fdget(sc.fd); - if (!f.file) + file = fget(sc.fd); + if (!file) return -EBADF; - cd.file = f.file; + cd.file = file; } ret = __io_sync_cancel(current->io_uring, &cd, sc.fd); @@ -338,6 +338,7 @@ int io_sync_cancel(struct io_ring_ctx *ctx, void __user *arg) if (ret == -ENOENT || ret > 0) ret = 0; out: - fdput(f); + if (file) + fput(file); return ret; } diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index bb8880d1e084..586ac65becfd 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -3607,7 +3607,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, size_t, argsz) { struct io_ring_ctx *ctx; - struct fd f; + struct file *file; long ret; if (unlikely(flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP | @@ -3625,20 +3625,19 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit, if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX)) return -EINVAL; fd = array_index_nospec(fd, IO_RINGFD_REG_MAX); - f.file = tctx->registered_rings[fd]; - f.flags = 0; - if (unlikely(!f.file)) + file = tctx->registered_rings[fd]; + if (unlikely(!file)) return -EBADF; } else { - f = fdget(fd); - if (unlikely(!f.file)) + file = fget(fd); + if (unlikely(!file)) return -EBADF; ret = -EOPNOTSUPP; - if (unlikely(!io_is_uring_fops(f.file))) + if (unlikely(!io_is_uring_fops(file))) goto out; } - ctx = f.file->private_data; + ctx = file->private_data; ret = -EBADFD; if (unlikely(ctx->flags & IORING_SETUP_R_DISABLED)) goto out; @@ -3732,7 +3731,8 @@ iopoll_locked: } } out: - fdput(f); + if (!(flags & IORING_ENTER_REGISTERED_RING)) + fput(file); return ret; } @@ -4573,7 +4573,7 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode, { struct io_ring_ctx *ctx; long ret = -EBADF; - struct fd f; + struct file *file; bool use_registered_ring; use_registered_ring = !!(opcode & IORING_REGISTER_USE_REGISTERED_RING); @@ -4592,27 +4592,27 @@ SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode, if (unlikely(!tctx || fd >= IO_RINGFD_REG_MAX)) return -EINVAL; fd = array_index_nospec(fd, IO_RINGFD_REG_MAX); - f.file = tctx->registered_rings[fd]; - f.flags = 0; - if (unlikely(!f.file)) + file = tctx->registered_rings[fd]; + if (unlikely(!file)) return -EBADF; } else { - f = fdget(fd); - if (unlikely(!f.file)) + file = fget(fd); + if (unlikely(!file)) return -EBADF; ret = -EOPNOTSUPP; - if (!io_is_uring_fops(f.file)) + if (!io_is_uring_fops(file)) goto out_fput; } - ctx = f.file->private_data; + ctx = file->private_data; mutex_lock(&ctx->uring_lock); ret = __io_uring_register(ctx, opcode, arg, nr_args); mutex_unlock(&ctx->uring_lock); trace_io_uring_register(ctx, opcode, ctx->nr_user_files, ctx->nr_user_bufs, ret); out_fput: - fdput(f); + if (!use_registered_ring) + fput(file); return ret; } |