From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from gardel.0pointer.net (gardel.0pointer.net [85.214.157.71]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1BAAC1D8DF6; Tue, 8 Oct 2024 11:51:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=85.214.157.71 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728388317; cv=none; b=UFsURpltYMXq+1GjgOAau/0Rh+yqJIx2/Nu7Ljfv7TGU9UzWBV5slPu9WJ0vE7iMsZcN7cNJNKxd6M2q1PgxWlo8IL7ih+CyQVEQQ+NHr/8MtMbGAMmQeXmtEm5hRHb1AYVGya/ziw2KAQTdfosOdOB88uRKJ8GKaMQCHY+7a6I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728388317; c=relaxed/simple; bh=pD1UuK9TzGO7wHfJxW6KD6klX9AkmnYXRgKL2KM14/c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CL6/6T+O927XVr3jSQzGSuGIpfCDnjzTpRZ+h++s1DK4KlvWSmHIkbiI1fLI15vriOZpjbFrlFsLSkKWS2BMNnvenXydLcK+HlqA8sX+KJjwBQiNMRFzu7bmuYnazQewTMc2zixhnKaCMFQFceC4LnOjtvLIzDp/h9QEGzUZBmE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=poettering.net; spf=pass smtp.mailfrom=poettering.net; arc=none smtp.client-ip=85.214.157.71 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=poettering.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=poettering.net Received: from gardel-login.0pointer.net (gardel-mail [85.214.157.71]) by gardel.0pointer.net (Postfix) with ESMTP id D4F82E8010A; Tue, 8 Oct 2024 13:41:43 +0200 (CEST) Received: by gardel-login.0pointer.net (Postfix, from userid 1000) id 2D95A1601D0; Tue, 8 Oct 2024 13:41:40 +0200 (CEST) Date: Tue, 8 Oct 2024 13:41:40 +0200 From: Lennart Poettering To: Christian Brauner Cc: Linus Torvalds , Jeff Layton , Josef Bacik , Alexander Viro , Jan Kara , linux-fsdevel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] fcntl: make F_DUPFD_QUERY associative Message-ID: References: <20241008-duften-formel-251f967602d5@brauner> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20241008-duften-formel-251f967602d5@brauner> On Di, 08.10.24 13:30, Christian Brauner (brauner@kernel.org) wrote: > Currently when passing a closed file descriptor to > fcntl(fd, F_DUPFD_QUERY, fd_dup) the order matters: > > fd = open("/dev/null"); > fd_dup = dup(fd); > > When we now close one of the file descriptors we get: > > (1) fcntl(fd, fd_dup) // -EBADF > (2) fcntl(fd_dup, fd) // 0 aka not equal > > depending on which file descriptor is passed first. That's not a huge > deal but it gives the api I slightly weird feel. Make it so that the > order doesn't matter by requiring that both file descriptors are valid: > > (1') fcntl(fd, fd_dup) // -EBADF > (2') fcntl(fd_dup, fd) // -EBADF > > Fixes: c62b758bae6a ("fcntl: add F_DUPFD_QUERY fcntl()") > Cc: > Reported-by: Lennart Poettering > Signed-off-by: Christian Brauner > --- > fs/fcntl.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/fs/fcntl.c b/fs/fcntl.c > index 22dd9dcce7ec..3d89de31066a 100644 > --- a/fs/fcntl.c > +++ b/fs/fcntl.c > @@ -397,6 +397,9 @@ static long f_dupfd_query(int fd, struct file *filp) > { > CLASS(fd_raw, f)(fd); > > + if (fd_empty(f)) > + return -EBADF; > + > /* > * We can do the 'fdput()' immediately, as the only thing that > * matters is the pointer value which isn't changed by the fdput. Thanks! LGTM! Reviewed-By: Lennart Poettering Lennart -- Lennart Poettering, Berlin