From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from integral2.. (unknown [36.72.214.231]) by gnuweeb.org (Postfix) with ESMTPSA id 2708E7E24F; Mon, 7 Feb 2022 14:06:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gnuweeb.org; s=default; t=1644242766; bh=G0B/qx9vzzQxYGDcP1samCsqc9aLd8Wtz9Gxg69dd2I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F6YNv0l9aRMeGzi7VwFsEMtzG3zQaKwAxd1XnR2M3BlpSiMHYKFvabS7/OpjqfbXi eMVuZ5yNmJcV54+mSeqvGkRHHqSrI0i1CwI5GJlXMco28NE9L5Hjr5LhCqVUXR2AV+ YxVMPyTunprBdUMqqdd8cuEWNrgC/Xjn48JaucpXdDFMF1Q1UhFyluTujQEY/z1ZUA oLk9/QWwoTatM/PuQ/80T585UTJWC+zoR2UOPIs01NmXGivafTILP12QQe7C8SdAOV yastEbo9QPOn2C9M8r4oVMAlV8Rh2tZLKZtNkv2MAiVfSdnynzTtMzM7k9oJ1bnJte lKz9eZJAsrGgA== From: Ammar Faizi To: Jens Axboe Cc: GNU/Weeb Mailing List , io-uring Mailing list , Tea Inside Mailing List , Linux Kernel Mailing List , Alviro Iskandar Setiawan , kernel test robot , Dan Carpenter , "Chen, Rong A" , Pavel Begunkov , Ammar Faizi Subject: [PATCH io_uring-5.17 v2] io_uring: Clean up a false-positive warning from GCC 9.3.0 Date: Mon, 7 Feb 2022 21:05:33 +0700 Message-Id: <20220207140533.565411-1-ammarfaizi2@gnuweeb.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <91e8ca64-0670-d998-73d8-f75ec5264cb0@kernel.dk> References: <20220207114315.555413-1-ammarfaizi2@gnuweeb.org> <91e8ca64-0670-d998-73d8-f75ec5264cb0@kernel.dk> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: From: Alviro Iskandar Setiawan In io_recv(), if import_single_range() fails, the @flags variable is uninitialized, then it will goto out_free. After the goto, the compiler doesn't know that (ret < min_ret) is always true, so it thinks the "if ((flags & MSG_WAITALL) ..." path could be taken. The complaint comes from gcc-9 (Debian 9.3.0-22) 9.3.0: ``` fs/io_uring.c:5238 io_recvfrom() error: uninitialized symbol 'flags' ``` Fix this by bypassing the @ret and @flags check when import_single_range() fails. Reasons: 1. import_single_range() only returns -EFAULT when it fails. 2. At that point, @flags is uninitialized and shouldn't be read. Reported-by: kernel test robot Reported-by: Dan Carpenter Reported-by: "Chen, Rong A" Link: https://lore.gnuweeb.org/timl/d33bb5a9-8173-f65b-f653-51fc0681c6d6@intel.com/ Cc: Pavel Begunkov Suggested-by: Ammar Faizi Fixes: 7297ce3d59449de49d3c9e1f64ae25488750a1fc ("io_uring: improve send/recv error handling") Signed-off-by: Alviro Iskandar Setiawan Signed-off-by: Ammar Faizi --- v2: - Update the subject line fs/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 2e04f718319d..3445c4da0153 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5228,7 +5228,6 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags) min_ret = iov_iter_count(&msg.msg_iter); ret = sock_recvmsg(sock, &msg, flags); -out_free: if (ret < min_ret) { if (ret == -EAGAIN && force_nonblock) return -EAGAIN; @@ -5236,9 +5235,9 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags) ret = -EINTR; req_set_fail(req); } else if ((flags & MSG_WAITALL) && (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) { +out_free: req_set_fail(req); } - __io_req_complete(req, issue_flags, ret, io_put_kbuf(req)); return 0; } base-commit: f6133fbd373811066c8441737e65f384c8f31974 -- 2.32.0