From: Caleb Sander Mateos Date: Thu, 4 Sep 2025 17:08:59 +0000 (-0600) Subject: io_uring/rsrc: respect submitter_task in io_register_clone_buffers() X-Git-Tag: v6.18-rc1~137^2~28 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2f076a453f75de691a081c89bce31b530153d53b;p=thirdparty%2Flinux.git io_uring/rsrc: respect submitter_task in io_register_clone_buffers() io_ring_ctx's enabled with IORING_SETUP_SINGLE_ISSUER are only allowed a single task submitting to the ctx. Although the documentation only mentions this restriction applying to io_uring_enter() syscalls, commit d7cce96c449e ("io_uring: limit registration w/ SINGLE_ISSUER") extends it to io_uring_register(). Ensuring only one task interacts with the io_ring_ctx will be important to allow this task to avoid taking the uring_lock. There is, however, one gap in these checks: io_register_clone_buffers() may take the uring_lock on a second (source) io_ring_ctx, but __io_uring_register() only checks the current thread against the *destination* io_ring_ctx's submitter_task. Fail the IORING_REGISTER_CLONE_BUFFERS with -EEXIST if the source io_ring_ctx has a registered submitter_task other than the current task. Signed-off-by: Caleb Sander Mateos Signed-off-by: Jens Axboe --- diff --git a/io_uring/rsrc.c b/io_uring/rsrc.c index 2d15b8785a95a..d787c16dc1c3a 100644 --- a/io_uring/rsrc.c +++ b/io_uring/rsrc.c @@ -1300,10 +1300,17 @@ int io_register_clone_buffers(struct io_ring_ctx *ctx, void __user *arg) if (src_ctx != ctx) { mutex_unlock(&ctx->uring_lock); lock_two_rings(ctx, src_ctx); + + if (src_ctx->submitter_task && + src_ctx->submitter_task != current) { + ret = -EEXIST; + goto out; + } } ret = io_clone_buffers(ctx, src_ctx, &buf); +out: if (src_ctx != ctx) mutex_unlock(&src_ctx->uring_lock);