linux-kernel - Re: [syzbot] general protection fault in __io_sync

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Date:   Wed, 24 Aug 2022 11:22:23 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     syzbot <syzbot+bf76847df5f7359c9e09@...kaller.appspotmail.com>,
        asml.silence@...il.com, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] general protection fault in __io_sync_cancel

On 8/24/22 11:20 AM, syzbot wrote:
> Hello,
> 
> syzbot tried to test the proposed patch but the build/boot failed:

Gah, that's the virtio-net issue that got fixed, not related. Maybe test
this one on master:

diff --git a/io_uring/cancel.c b/io_uring/cancel.c
index e4e1dc0325f0..5fc5d3e80fcb 100644
--- a/io_uring/cancel.c
+++ b/io_uring/cancel.c
@@ -218,7 +218,7 @@ static int __io_sync_cancel(struct io_uring_task *tctx,
 	    (cd->flags & IORING_ASYNC_CANCEL_FD_FIXED)) {
 		unsigned long file_ptr;
 
-		if (unlikely(fd > ctx->nr_user_files))
+		if (unlikely(fd >= ctx->nr_user_files))
 			return -EBADF;
 		fd = array_index_nospec(fd, ctx->nr_user_files);
 		file_ptr = io_fixed_file_slot(&ctx->file_table, fd)->file_ptr;

-- 
Jens Axboe