From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 18F0F3A1E8C; Tue, 31 Mar 2026 17:00:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976402; cv=none; b=L4YTGAQz2RrahfVrtX8ia/RCIHyyih+c21EAsMnUREJ/oDC5dk/K5UGu7QgaVOTh/ldmrdnqvnxJ/QevpModFl3wZXTIyze272cyZeF3Vca5auhKOcMQDL+yZzz28QfWOS45JClfP3a8FgOJK/kyIvJE9DvbBZs/IIYL+R5kDPk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774976402; c=relaxed/simple; bh=QdddpCzNslIpHjyyP2he+/toZzTcaX64KQUk/bs4JoA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=raN4zfHqpU44AtRZZGNnjrxV/DuDA8npadFFsAykCfL9bV57wcTTTVzo/3HfsdjtSlNGJOSTMQgHUVIqwybkGzZUkKend8HSmchggLFumaqZlOh6BK5DA0hudBzrNKtpP42O5J/KYUa6YrnVgXpKA8RSUDFNMisRFKrtcXmOEXs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=d1xP40oE; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="d1xP40oE" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4EA52C19423; Tue, 31 Mar 2026 17:00:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1774976402; bh=QdddpCzNslIpHjyyP2he+/toZzTcaX64KQUk/bs4JoA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=d1xP40oE4RrSQUVDoy5rPyEiweP73MDRCBu5Ib0bfhzAr7p+oY3Ug6nqE/7c+3WQk XQbGQ9WJsL9Od/Eyr2eCaPoTbJU6VZUQhaRq9gus+ED30pTRMYFNlCjd8Hza2S+sAp GvKksXLArXJodY3UYyn6WQS81nHn1Fl5TyFJqGR4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Alexander Potapenko , Shigeru Yoshida , Marek Szyprowski , Sasha Levin Subject: [PATCH 6.18 078/309] dma: swiotlb: add KMSAN annotations to swiotlb_bounce() Date: Tue, 31 Mar 2026 18:19:41 +0200 Message-ID: <20260331161756.358866019@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260331161753.468533260@linuxfoundation.org> References: <20260331161753.468533260@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Shigeru Yoshida [ Upstream commit 6f770b73d0311a5b099277653199bb6421c4fed2 ] When a device performs DMA to a bounce buffer, KMSAN is unaware of the write and does not mark the data as initialized. When swiotlb_bounce() later copies the bounce buffer back to the original buffer, memcpy propagates the uninitialized shadow to the original buffer, causing false positive uninit-value reports. Fix this by calling kmsan_unpoison_memory() on the bounce buffer before copying it back in the DMA_FROM_DEVICE path, so that memcpy naturally propagates initialized shadow to the destination. Suggested-by: Alexander Potapenko Link: https://lore.kernel.org/CAG_fn=WUGta-paG1BgsGRoAR+fmuCgh3xo=R3XdzOt_-DqSdHw@mail.gmail.com/ Fixes: 7ade4f10779c ("dma: kmsan: unpoison DMA mappings") Signed-off-by: Shigeru Yoshida Signed-off-by: Marek Szyprowski Link: https://lore.kernel.org/r/20260315082750.2375581-1-syoshida@redhat.com Signed-off-by: Sasha Levin --- kernel/dma/swiotlb.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 0d37da3d95b65..e27225f8aeb27 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -30,6 +30,7 @@ #include #include #include +#include #include #include #include @@ -903,10 +904,19 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size local_irq_save(flags); page = pfn_to_page(pfn); - if (dir == DMA_TO_DEVICE) + if (dir == DMA_TO_DEVICE) { + /* + * Ideally, kmsan_check_highmem_page() + * could be used here to detect infoleaks, + * but callers may map uninitialized buffers + * that will be written by the device, + * causing false positives. + */ memcpy_from_page(vaddr, page, offset, sz); - else + } else { + kmsan_unpoison_memory(vaddr, sz); memcpy_to_page(page, offset, vaddr, sz); + } local_irq_restore(flags); size -= sz; @@ -915,8 +925,15 @@ static void swiotlb_bounce(struct device *dev, phys_addr_t tlb_addr, size_t size offset = 0; } } else if (dir == DMA_TO_DEVICE) { + /* + * Ideally, kmsan_check_memory() could be used here to detect + * infoleaks (uninitialized data being sent to device), but + * callers may map uninitialized buffers that will be written + * by the device, causing false positives. + */ memcpy(vaddr, phys_to_virt(orig_addr), size); } else { + kmsan_unpoison_memory(vaddr, size); memcpy(phys_to_virt(orig_addr), vaddr, size); } } -- 2.51.0