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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id m1sm3115007pjv.22.2019.06.07.21.03.43 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 07 Jun 2019 21:03:44 -0700 (PDT) Date: Fri, 7 Jun 2019 21:03:43 -0700 From: Kees Cook To: Andrey Konovalov Subject: Re: [PATCH v16 09/16] fs, arm64: untag user pointers in fs/userfaultfd.c Message-ID: <201906072102.B58E6A609C@keescook> References: <7d6fef00d7daf647b5069101da8cf5a202da75b0.1559580831.git.andreyknvl@google.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <7d6fef00d7daf647b5069101da8cf5a202da75b0.1559580831.git.andreyknvl@google.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190607_210346_452891_B7223DC3 X-CRM114-Status: GOOD ( 20.06 ) 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: Mark Rutland , kvm@vger.kernel.org, Szabolcs Nagy , Catalin Marinas , Will Deacon , dri-devel@lists.freedesktop.org, linux-mm@kvack.org, Khalid Aziz , linux-kselftest@vger.kernel.org, Felix Kuehling , Vincenzo Frascino , Jacob Bramley , Leon Romanovsky , linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org, Christoph Hellwig , Jason Gunthorpe , Dmitry Vyukov , Dave Martin , Evgeniy Stepanov , linux-media@vger.kernel.org, Kevin Brodsky , Ruben Ayrapetyan , Ramana Radhakrishnan , Alex Williamson , Mauro Carvalho Chehab , linux-arm-kernel@lists.infradead.org, Kostya Serebryany , Greg Kroah-Hartman , Yishai Hadas , linux-kernel@vger.kernel.org, Jens Wiklander , Lee Smith , Alexander Deucher , Andrew Morton , enh , Robin Murphy , Christian Koenig , Luc Van Oostenryck Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Mon, Jun 03, 2019 at 06:55:11PM +0200, 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. > > userfaultfd code use provided user pointers for vma lookups, which can > only by done with untagged pointers. > > Untag user pointers in validate_range(). > > Signed-off-by: Andrey Konovalov "userfaultfd: untag user pointers" Reviewed-by: Kees Cook -Kees > --- > fs/userfaultfd.c | 22 ++++++++++++---------- > 1 file changed, 12 insertions(+), 10 deletions(-) > > diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c > index 3b30301c90ec..24d68c3b5ee2 100644 > --- a/fs/userfaultfd.c > +++ b/fs/userfaultfd.c > @@ -1263,21 +1263,23 @@ static __always_inline void wake_userfault(struct userfaultfd_ctx *ctx, > } > > static __always_inline int validate_range(struct mm_struct *mm, > - __u64 start, __u64 len) > + __u64 *start, __u64 len) > { > __u64 task_size = mm->task_size; > > - if (start & ~PAGE_MASK) > + *start = untagged_addr(*start); > + > + if (*start & ~PAGE_MASK) > return -EINVAL; > if (len & ~PAGE_MASK) > return -EINVAL; > if (!len) > return -EINVAL; > - if (start < mmap_min_addr) > + if (*start < mmap_min_addr) > return -EINVAL; > - if (start >= task_size) > + if (*start >= task_size) > return -EINVAL; > - if (len > task_size - start) > + if (len > task_size - *start) > return -EINVAL; > return 0; > } > @@ -1327,7 +1329,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx, > goto out; > } > > - ret = validate_range(mm, uffdio_register.range.start, > + ret = validate_range(mm, &uffdio_register.range.start, > uffdio_register.range.len); > if (ret) > goto out; > @@ -1516,7 +1518,7 @@ static int userfaultfd_unregister(struct userfaultfd_ctx *ctx, > if (copy_from_user(&uffdio_unregister, buf, sizeof(uffdio_unregister))) > goto out; > > - ret = validate_range(mm, uffdio_unregister.start, > + ret = validate_range(mm, &uffdio_unregister.start, > uffdio_unregister.len); > if (ret) > goto out; > @@ -1667,7 +1669,7 @@ static int userfaultfd_wake(struct userfaultfd_ctx *ctx, > if (copy_from_user(&uffdio_wake, buf, sizeof(uffdio_wake))) > goto out; > > - ret = validate_range(ctx->mm, uffdio_wake.start, uffdio_wake.len); > + ret = validate_range(ctx->mm, &uffdio_wake.start, uffdio_wake.len); > if (ret) > goto out; > > @@ -1707,7 +1709,7 @@ static int userfaultfd_copy(struct userfaultfd_ctx *ctx, > sizeof(uffdio_copy)-sizeof(__s64))) > goto out; > > - ret = validate_range(ctx->mm, uffdio_copy.dst, uffdio_copy.len); > + ret = validate_range(ctx->mm, &uffdio_copy.dst, uffdio_copy.len); > if (ret) > goto out; > /* > @@ -1763,7 +1765,7 @@ static int userfaultfd_zeropage(struct userfaultfd_ctx *ctx, > sizeof(uffdio_zeropage)-sizeof(__s64))) > goto out; > > - ret = validate_range(ctx->mm, uffdio_zeropage.range.start, > + ret = validate_range(ctx->mm, &uffdio_zeropage.range.start, > uffdio_zeropage.range.len); > if (ret) > goto out; > -- > 2.22.0.rc1.311.g5d7573a151-goog > -- Kees Cook _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel