netdev - [PATCH 3/9] fs: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check

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Date:   Fri, 18 Sep 2020 14:45:27 +0200
From:   Christoph Hellwig <hch@....de>
To:     Alexander Viro <viro@...iv.linux.org.uk>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Jens Axboe <axboe@...nel.dk>, Arnd Bergmann <arnd@...db.de>,
        David Howells <dhowells@...hat.com>,
        linux-arm-kernel@...ts.infradead.org, x86@...nel.org,
        linux-kernel@...r.kernel.org, linux-mips@...r.kernel.org,
        linux-parisc@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-s390@...r.kernel.org, sparclinux@...r.kernel.org,
        linux-block@...r.kernel.org, linux-scsi@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, linux-aio@...ck.org,
        io-uring@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-mm@...ck.org, netdev@...r.kernel.org,
        keyrings@...r.kernel.org, linux-security-module@...r.kernel.org
Subject: [PATCH 3/9] fs: explicitly check for CHECK_IOVEC_ONLY in rw_copy_check_uvector

Explicitly check for the magic value insted of implicitly relying on
its number representation.

Signed-off-by: Christoph Hellwig <hch@....de>
---
 fs/read_write.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/read_write.c b/fs/read_write.c
index 5db58b8c78d0dd..f153116bc5399b 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -840,8 +840,7 @@ ssize_t rw_copy_check_uvector(int type, const struct iovec __user * uvector,
 			ret = -EINVAL;
 			goto out;
 		}
-		if (type >= 0
-		    && unlikely(!access_ok(buf, len))) {
+		if (type != CHECK_IOVEC_ONLY && unlikely(!access_ok(buf, len))) {
 			ret = -EFAULT;
 			goto out;
 		}
@@ -911,7 +910,7 @@ ssize_t compat_rw_copy_check_uvector(int type,
 		}
 		if (len < 0)	/* size_t not fitting in compat_ssize_t .. */
 			goto out;
-		if (type >= 0 &&
+		if (type != CHECK_IOVEC_ONLY &&
 		    !access_ok(compat_ptr(buf), len)) {
 			ret = -EFAULT;
 			goto out;
-- 
2.28.0