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Date: Tue, 11 Jun 2019 14:06:09 -0600 From: Khalid Aziz <khalid.aziz@...cle.com> To: Andrey Konovalov <andreyknvl@...gle.com>, linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, amd-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org, linux-rdma@...r.kernel.org, linux-media@...r.kernel.org, kvm@...r.kernel.org, linux-kselftest@...r.kernel.org Cc: Catalin Marinas <catalin.marinas@....com>, Vincenzo Frascino <vincenzo.frascino@....com>, Will Deacon <will.deacon@....com>, Mark Rutland <mark.rutland@....com>, Andrew Morton <akpm@...ux-foundation.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Kees Cook <keescook@...omium.org>, Yishai Hadas <yishaih@...lanox.com>, Felix Kuehling <Felix.Kuehling@....com>, Alexander Deucher <Alexander.Deucher@....com>, Christian Koenig <Christian.Koenig@....com>, Mauro Carvalho Chehab <mchehab@...nel.org>, Jens Wiklander <jens.wiklander@...aro.org>, Alex Williamson <alex.williamson@...hat.com>, Leon Romanovsky <leon@...nel.org>, Luc Van Oostenryck <luc.vanoostenryck@...il.com>, Dave Martin <Dave.Martin@....com>, enh <enh@...gle.com>, Jason Gunthorpe <jgg@...pe.ca>, Christoph Hellwig <hch@...radead.org>, Dmitry Vyukov <dvyukov@...gle.com>, Kostya Serebryany <kcc@...gle.com>, Evgeniy Stepanov <eugenis@...gle.com>, Lee Smith <Lee.Smith@....com>, Ramana Radhakrishnan <Ramana.Radhakrishnan@....com>, Jacob Bramley <Jacob.Bramley@....com>, Ruben Ayrapetyan <Ruben.Ayrapetyan@....com>, Robin Murphy <robin.murphy@....com>, Kevin Brodsky <kevin.brodsky@....com>, Szabolcs Nagy <Szabolcs.Nagy@....com> Subject: Re: [PATCH v16 03/16] lib, arm64: untag user pointers in strn*_user On 6/3/19 10:55 AM, Andrey Konovalov wrote: > This patch is a part of a series that extends arm64 kernel ABI to allow to > pass tagged user pointers (with the top byte set to something else other > than 0x00) as syscall arguments. > > strncpy_from_user and strnlen_user accept user addresses as arguments, and > do not go through the same path as copy_from_user and others, so here we > need to handle the case of tagged user addresses separately. > > Untag user pointers passed to these functions. > > Note, that this patch only temporarily untags the pointers to perform > validity checks, but then uses them as is to perform user memory accesses. > > Reviewed-by: Catalin Marinas <catalin.marinas@....com> > Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com> > --- > lib/strncpy_from_user.c | 3 ++- > lib/strnlen_user.c | 3 ++- > 2 files changed, 4 insertions(+), 2 deletions(-) Looks good. Reviewed-by: Khalid Aziz <khalid.aziz@...cle.com> > > diff --git a/lib/strncpy_from_user.c b/lib/strncpy_from_user.c > index 023ba9f3b99f..dccb95af6003 100644 > --- a/lib/strncpy_from_user.c > +++ b/lib/strncpy_from_user.c > @@ -6,6 +6,7 @@ > #include <linux/uaccess.h> > #include <linux/kernel.h> > #include <linux/errno.h> > +#include <linux/mm.h> > > #include <asm/byteorder.h> > #include <asm/word-at-a-time.h> > @@ -108,7 +109,7 @@ long strncpy_from_user(char *dst, const char __user *src, long count) > return 0; > > max_addr = user_addr_max(); > - src_addr = (unsigned long)src; > + src_addr = (unsigned long)untagged_addr(src); > if (likely(src_addr < max_addr)) { > unsigned long max = max_addr - src_addr; > long retval; > diff --git a/lib/strnlen_user.c b/lib/strnlen_user.c > index 7f2db3fe311f..28ff554a1be8 100644 > --- a/lib/strnlen_user.c > +++ b/lib/strnlen_user.c > @@ -2,6 +2,7 @@ > #include <linux/kernel.h> > #include <linux/export.h> > #include <linux/uaccess.h> > +#include <linux/mm.h> > > #include <asm/word-at-a-time.h> > > @@ -109,7 +110,7 @@ long strnlen_user(const char __user *str, long count) > return 0; > > max_addr = user_addr_max(); > - src_addr = (unsigned long)str; > + src_addr = (unsigned long)untagged_addr(str); > if (likely(src_addr < max_addr)) { > unsigned long max = max_addr - src_addr; > long retval; >
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