From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-il1-f199.google.com (mail-il1-f199.google.com [209.85.166.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8CDF81D5CC6 for ; Mon, 31 Mar 2025 08:06:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.166.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743408415; cv=none; b=X0JWxrwCxrXe2vSlUMtTkJb4a3uI1Z11aAl59k+CU7MJCi0dV4rs6aInE9kP5cPoCsX08tVWl1ScjX/Bf0pio+mfdNTt+7vxXB6Vs2Zu32N3OB4gdRqonOG2eFWKxr/g52Gr113dHudL5ALh4hSZ5oGzNpXUVKO1k8iMEsnfuR4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743408415; c=relaxed/simple; bh=3jBatRXDVualpNCQqPu9fTtm3RuHDjRzaBOaXCmxQSc=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To:Cc: Content-Type; b=hHdbOSlwewsXAYYyhLX1SwyUCOafCu/HJo4Cm5J6z2VCFXqC3xgvfhxdbArqkGzdBbSzVz79kJ/lfZ5ZVUj/ccAgaePDAlDVOLRndReW9awikbuYQ9HZFLknYhZ8CkSWgDT/Hf4wFSkLYMDtWaRfe4ABYyEjKzHL5Vhd5oJDMsA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=209.85.166.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-il1-f199.google.com with SMTP id e9e14a558f8ab-3d5a9e7dd5aso44955565ab.3 for ; Mon, 31 Mar 2025 01:06:53 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743408412; x=1744013212; h=cc:to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=1N2IlYmogkl1BCwYrDbBWJW9jRi8jD9aDkBGY1rBpjA=; b=gT996v/22UPF+vJO5DkO73yRstV+oyL8KXEXgYf3EDYUjzWooAFqBX6iQBDQAGoHi4 C0RIuuBxo0Xj0fcPJkAKyUETUZ9Pr2pjWeXKvE9Ab7F7J+reqpF6VYX2Lq3MiOrJHuBE a9+wkmpQzLE2hPpAcbn1IU0DIsYK75qxJzJwBzhd+cMnCzl/d0RcvineSHUfQcQ6RK6h OnWNw0rdipRgHys8Oj41kdoozPsMCL/8JFHEOXjnBSeWYwGoB6+AxE/rxyXKUKB8yE1x dYBXkoq9L+fTK388ghpNZb1oczQoOXdIA8OHFhlePJDe3cYdClR7Xj8MX4QMuBK8lYnc IEoA== X-Forwarded-Encrypted: i=1; AJvYcCUT2arbbXr342m14RiEWHtnFpDVLRLzzniXzVJgjuAnj+co1I9Q+Ukt84c9O5ATLPK6gtdfo6SwPc/20QM=@vger.kernel.org X-Gm-Message-State: AOJu0YwOqUBkFecxBV+KsDWmNF2PncCFrw3E6pxwzIANE7NT1CJTm3wc 4iny8avMnUTMtziwUekFXFfdBbhNFwJK7ttf9Tc0b0j2mxzYtskfvNkUUBKymgqgoQx5PEyAZNt BN5une58WmUbuA7rGVDCS3bdzdL04+i35nPzcqVssbdKIdB8uyeQBkDo= X-Google-Smtp-Source: AGHT+IET23zu9tlwVBsyEgW7egXSSD3VInVvV6doXQWpbvjplVWicxmICEMhEa/SvpiyVoRAJQZ5hkfjuzTe2YIkQHSu183Qxz50 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a92:cdae:0:b0:3d4:2306:6d0 with SMTP id e9e14a558f8ab-3d5e09c8ff7mr67421795ab.14.1743408412676; Mon, 31 Mar 2025 01:06:52 -0700 (PDT) Date: Mon, 31 Mar 2025 01:06:52 -0700 In-Reply-To: <164861.1743408402@warthog.procyon.org.uk> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <67ea4d1c.050a0220.1547ec.0121.GAE@google.com> Subject: Re: [syzbot] [afs?] BUG: sleeping function called from invalid context in __do_fault From: syzbot To: dhowells@redhat.com Cc: dhowells@redhat.com, linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org, marc.dionne@auristor.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" > #syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master This crash does not have a reproducer. I cannot test it. > > commit db7a516159869b19f237c73bd75599bbe0bfcc4d > Author: David Howells > Date: Fri Mar 28 16:46:58 2025 +0000 > > afs: Fix afs_dynroot_readdir() to not use the RCU read lock > > afs_dynroot_readdir() uses the RCU read lock to walk the cell list whilst > emitting cell automount entries - but dir_emit() may write to a userspace > buffer, thereby causing a fault to occur and waits to happen. > > Fix afs_dynroot_readdir() to get a shared lock on net->cells_lock instead. > > Fixes: 1d0b929fc070 ("afs: Change dynroot to create contents on demand") > Reported-by: syzbot+3b6c5c6a1d0119b687a1@syzkaller.appspotmail.com > Signed-off-by: David Howells > cc: Marc Dionne > cc: linux-afs@lists.infradead.org > cc: linux-fsdevel@vger.kernel.org > > diff --git a/fs/afs/dynroot.c b/fs/afs/dynroot.c > index 691e0ae607a1..8c6130789fde 100644 > --- a/fs/afs/dynroot.c > +++ b/fs/afs/dynroot.c > @@ -348,9 +348,9 @@ static int afs_dynroot_readdir(struct file *file, struct dir_context *ctx) > } > > if ((unsigned long long)ctx->pos <= AFS_MAX_DYNROOT_CELL_INO) { > - rcu_read_lock(); > + down_read(&net->cells_lock); > ret = afs_dynroot_readdir_cells(net, ctx); > - rcu_read_unlock(); > + up_read(&net->cells_lock); > } > return ret; > } >