linux-kernel - Re: [syzbot] [io-uring?] general protection fault in io_uring_show

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Message-ID: <544a6062-1af4-4686-bc70-823a6dbca38b@kernel.dk>
Date:   Fri, 1 Sep 2023 13:59:07 -0600
From:   Jens Axboe <axboe@...nel.dk>
To:     syzbot <syzbot+216e2ea6e0bf4a0acdd7@...kaller.appspotmail.com>,
        asml.silence@...il.com, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [io-uring?] general protection fault in
 io_uring_show_fdinfo

On 9/1/23 11:22 AM, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    99d99825fc07 Merge tag 'nfs-for-6.6-1' of git://git.linux-..
> git tree:       upstream
> console+strace: https://syzkaller.appspot.com/x/log.txt?x=12e9fc13a80000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=cce54b04d9a3d05b
> dashboard link: https://syzkaller.appspot.com/bug?extid=216e2ea6e0bf4a0acdd7
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1749fa10680000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=10211c10680000

This should fix it:

diff --git a/io_uring/fdinfo.c b/io_uring/fdinfo.c
index 300455b4bc12..c53678875416 100644
--- a/io_uring/fdinfo.c
+++ b/io_uring/fdinfo.c
@@ -93,6 +93,8 @@ __cold void io_uring_show_fdinfo(struct seq_file *m, struct file *f)
 		struct io_uring_sqe *sqe;
 		unsigned int sq_idx;
 
+		if (ctx->flags & IORING_SETUP_NO_SQARRAY)
+			break;
 		sq_idx = READ_ONCE(ctx->sq_array[entry & sq_mask]);
 		if (sq_idx > sq_mask)
 			continue;

-- 
Jens Axboe