From nobody Fri Dec 19 20:34:51 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 42994ECAAA1 for ; Thu, 15 Sep 2022 15:08:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230470AbiIOPIq (ORCPT ); Thu, 15 Sep 2022 11:08:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48602 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230475AbiIOPHN (ORCPT ); Thu, 15 Sep 2022 11:07:13 -0400 Received: from mail-ed1-x549.google.com (mail-ed1-x549.google.com [IPv6:2a00:1450:4864:20::549]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id AE4F894111 for ; Thu, 15 Sep 2022 08:05:37 -0700 (PDT) Received: by mail-ed1-x549.google.com with SMTP id r11-20020a05640251cb00b004516feb8c09so10385466edd.10 for ; Thu, 15 Sep 2022 08:05:37 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date; bh=oN1DmmB5hIGSextjMwU3Vnw2pm00V4zpd8aSRnyHf0Q=; b=HBcCaYgx3GOtGCD6vnRBTt3kop2ZY2C8h5F9Ts8g8FkVWY7Gs7+q7OujqY0j58mgyQ PpKv7dBrhRa+ULEFZpq6YIT9w4lLPJ3o23t1xy0FoDWMsuNH+5woxQMACI2EuJ0T06Fk TQpHI9dVcGN06VXZ17nt89f3hGpMkQO1B4jODqCAJBkjoP8KIDq6UcAT4rCV9jZa2ghf 6IC/hqZCHCxTjCfjDa3/RbfIoLX91TF8zSHe2qs82MOMbXBLbenq9eBUsVb3VSvh8+SB RdQyFUC4o4BFHFnVb96baewEylVhQuM+iDRPQR9M1/qp1ZO94YJAenY82wc+l2ZQVZqV A61g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date; bh=oN1DmmB5hIGSextjMwU3Vnw2pm00V4zpd8aSRnyHf0Q=; b=2xkVNdEUWUCLF7z+6pNiVsPm3yiy/MkLVGZW+Wvg0n+u0GThg0dxE29dAWGqLyU9a5 H7JmX5bLqQhSUTbeYR9oM/d5xBYf558afd+ABQkpO4ulSGgXZ7z1evF0tcJTk0ql3F2u TW97rIjNGSQYN6W3MRix1OnJuHG61rwaDrssTBM8VSt6t4/bCTBSriDpLOegS5qGAOph kanoUEGepCE4Go7/MMBmrq0iHahXLtHVNuKKDc/R6myhw4W0ZbsXJfjrb48L+2i22yGN xtG+0thEQRl1CD8kgA1w5YNJns2EsTVGVN+yK4i7tBUq4IaBlEieSYwn+DGxAlhRUxA8 EVEw== X-Gm-Message-State: ACrzQf12PBPyCBBwYzGLDet3cV06uiYRT17ePd4h/vkWB+/1c18jNONQ IyCCTSzgXzgxJtl5YL9LNzgR8S2tECQ= X-Google-Smtp-Source: AMsMyM6lsL6b9WP5OjlGGCg3dKk2Bj9nZi0tLG7AoCO3goElJf/yGauNpy2SVmCPAv5cw8xVUpzz1lwDIpM= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:686d:27b5:495:85b7]) (user=glider job=sendgmr) by 2002:a05:6402:2694:b0:450:d537:f6d6 with SMTP id w20-20020a056402269400b00450d537f6d6mr275499edd.344.1663254335996; Thu, 15 Sep 2022 08:05:35 -0700 (PDT) Date: Thu, 15 Sep 2022 17:03:55 +0200 In-Reply-To: <20220915150417.722975-1-glider@google.com> Mime-Version: 1.0 References: <20220915150417.722975-1-glider@google.com> X-Mailer: git-send-email 2.37.2.789.g6183377224-goog Message-ID: <20220915150417.722975-22-glider@google.com> Subject: [PATCH v7 21/43] dma: kmsan: unpoison DMA mappings From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Alexei Starovoitov , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Biggers , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Stephen Rothwell , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" KMSAN doesn't know about DMA memory writes performed by devices. We unpoison such memory when it's mapped to avoid false positive reports. Signed-off-by: Alexander Potapenko --- v2: -- move implementation of kmsan_handle_dma() and kmsan_handle_dma_sg() here v4: -- swap dma: and kmsan: int the subject v5: -- do not export KMSAN hooks that are not called from modules v6: -- add a missing #include Link: https://linux-review.googlesource.com/id/Ia162dc4c5a92e74d4686c1be32a= 4dfeffc5c32cd --- include/linux/kmsan.h | 41 ++++++++++++++++++++++++++++++ kernel/dma/mapping.c | 10 +++++--- mm/kmsan/hooks.c | 59 +++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 107 insertions(+), 3 deletions(-) diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h index e00de976ee438..dac296da45c55 100644 --- a/include/linux/kmsan.h +++ b/include/linux/kmsan.h @@ -9,6 +9,7 @@ #ifndef _LINUX_KMSAN_H #define _LINUX_KMSAN_H =20 +#include #include #include #include @@ -16,6 +17,7 @@ struct page; struct kmem_cache; struct task_struct; +struct scatterlist; =20 #ifdef CONFIG_KMSAN =20 @@ -172,6 +174,35 @@ void kmsan_ioremap_page_range(unsigned long addr, unsi= gned long end, */ void kmsan_iounmap_page_range(unsigned long start, unsigned long end); =20 +/** + * kmsan_handle_dma() - Handle a DMA data transfer. + * @page: first page of the buffer. + * @offset: offset of the buffer within the first page. + * @size: buffer size. + * @dir: one of possible dma_data_direction values. + * + * Depending on @direction, KMSAN: + * * checks the buffer, if it is copied to device; + * * initializes the buffer, if it is copied from device; + * * does both, if this is a DMA_BIDIRECTIONAL transfer. + */ +void kmsan_handle_dma(struct page *page, size_t offset, size_t size, + enum dma_data_direction dir); + +/** + * kmsan_handle_dma_sg() - Handle a DMA transfer using scatterlist. + * @sg: scatterlist holding DMA buffers. + * @nents: number of scatterlist entries. + * @dir: one of possible dma_data_direction values. + * + * Depending on @direction, KMSAN: + * * checks the buffers in the scatterlist, if they are copied to device; + * * initializes the buffers, if they are copied from device; + * * does both, if this is a DMA_BIDIRECTIONAL transfer. + */ +void kmsan_handle_dma_sg(struct scatterlist *sg, int nents, + enum dma_data_direction dir); + #else =20 static inline void kmsan_init_shadow(void) @@ -254,6 +285,16 @@ static inline void kmsan_iounmap_page_range(unsigned l= ong start, { } =20 +static inline void kmsan_handle_dma(struct page *page, size_t offset, + size_t size, enum dma_data_direction dir) +{ +} + +static inline void kmsan_handle_dma_sg(struct scatterlist *sg, int nents, + enum dma_data_direction dir) +{ +} + #endif =20 #endif /* _LINUX_KMSAN_H */ diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 27f272381cf27..33437d6206445 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -10,6 +10,7 @@ #include #include #include +#include #include #include #include @@ -156,6 +157,7 @@ dma_addr_t dma_map_page_attrs(struct device *dev, struc= t page *page, addr =3D dma_direct_map_page(dev, page, offset, size, dir, attrs); else addr =3D ops->map_page(dev, page, offset, size, dir, attrs); + kmsan_handle_dma(page, offset, size, dir); debug_dma_map_page(dev, page, offset, size, dir, addr, attrs); =20 return addr; @@ -194,11 +196,13 @@ static int __dma_map_sg_attrs(struct device *dev, str= uct scatterlist *sg, else ents =3D ops->map_sg(dev, sg, nents, dir, attrs); =20 - if (ents > 0) + if (ents > 0) { + kmsan_handle_dma_sg(sg, nents, dir); debug_dma_map_sg(dev, sg, nents, ents, dir, attrs); - else if (WARN_ON_ONCE(ents !=3D -EINVAL && ents !=3D -ENOMEM && - ents !=3D -EIO && ents !=3D -EREMOTEIO)) + } else if (WARN_ON_ONCE(ents !=3D -EINVAL && ents !=3D -ENOMEM && + ents !=3D -EIO && ents !=3D -EREMOTEIO)) { return -EIO; + } =20 return ents; } diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index 5c0eb25d984d7..563c09443a37a 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -10,10 +10,12 @@ */ =20 #include +#include #include #include #include #include +#include #include #include =20 @@ -243,6 +245,63 @@ void kmsan_copy_to_user(void __user *to, const void *f= rom, size_t to_copy, } EXPORT_SYMBOL(kmsan_copy_to_user); =20 +static void kmsan_handle_dma_page(const void *addr, size_t size, + enum dma_data_direction dir) +{ + switch (dir) { + case DMA_BIDIRECTIONAL: + kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0, + REASON_ANY); + kmsan_internal_unpoison_memory((void *)addr, size, + /*checked*/ false); + break; + case DMA_TO_DEVICE: + kmsan_internal_check_memory((void *)addr, size, /*user_addr*/ 0, + REASON_ANY); + break; + case DMA_FROM_DEVICE: + kmsan_internal_unpoison_memory((void *)addr, size, + /*checked*/ false); + break; + case DMA_NONE: + break; + } +} + +/* Helper function to handle DMA data transfers. */ +void kmsan_handle_dma(struct page *page, size_t offset, size_t size, + enum dma_data_direction dir) +{ + u64 page_offset, to_go, addr; + + if (PageHighMem(page)) + return; + addr =3D (u64)page_address(page) + offset; + /* + * The kernel may occasionally give us adjacent DMA pages not belonging + * to the same allocation. Process them separately to avoid triggering + * internal KMSAN checks. + */ + while (size > 0) { + page_offset =3D addr % PAGE_SIZE; + to_go =3D min(PAGE_SIZE - page_offset, (u64)size); + kmsan_handle_dma_page((void *)addr, to_go, dir); + addr +=3D to_go; + size -=3D to_go; + } +} + +void kmsan_handle_dma_sg(struct scatterlist *sg, int nents, + enum dma_data_direction dir) +{ + struct scatterlist *item; + int i; + + for_each_sg(sg, item, nents, i) + kmsan_handle_dma(sg_page(item), item->offset, item->length, + dir); +} + /* Functions from kmsan-checks.h follow. */ void kmsan_poison_memory(const void *address, size_t size, gfp_t flags) { --=20 2.37.2.789.g6183377224-goog