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auth=pass smtp.auth=C51A453 smtp.mailfrom=david.laight@aculab.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200921_110537_279180_618219CD X-CRM114-Status: GOOD ( 16.61 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Jens Axboe , "linux-s390@vger.kernel.org" , "linux-arch@vger.kernel.org" , "linux-parisc@vger.kernel.org" , Arnd Bergmann , "linux-aio@kvack.org" , "netdev@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-mips@vger.kernel.org" , David Howells , "linux-fsdevel@vger.kernel.org" , "linux-security-module@vger.kernel.org" , "keyrings@vger.kernel.org" , "linux-block@vger.kernel.org" , "linux-mm@kvack.org" , "linux-scsi@vger.kernel.org" , "sparclinux@vger.kernel.org" , Andrew Morton , "linuxppc-dev@lists.ozlabs.org" , "io-uring@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org From: Christoph Hellwig > Sent: 21 September 2020 15:34 > > Explicitly check for the magic value insted of implicitly relying on > its numeric representation. Also drop the rather pointless unlikely > annotation. > > Signed-off-by: Christoph Hellwig > --- > lib/iov_iter.c | 5 ++--- > 1 file changed, 2 insertions(+), 3 deletions(-) > > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index d7e72343c360eb..a64867501a7483 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -1709,8 +1709,7 @@ static ssize_t rw_copy_check_uvector(int type, > ret = -EINVAL; > goto out; > } > - if (type >= 0 > - && unlikely(!access_ok(buf, len))) { > + if (type != CHECK_IOVEC_ONLY && !access_ok(buf, len)) { > ret = -EFAULT; > goto out; > } > @@ -1824,7 +1823,7 @@ static 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 I've actually no idea: 1) Why there is an access_ok() check here. It will be repeated by the user copy functions. 2) Why it isn't done when called from mm/process_vm_access.c. Ok, the addresses refer to a different process, but they must still be valid user addresses. Is 2 a legacy from when access_ok() actually checked that the addresses were mapped into the process's address space? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel