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 B589E6FAA for ; Mon, 3 Apr 2023 14:45:42 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3D042C433D2; Mon, 3 Apr 2023 14:45:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680533142; bh=COH24gq4e/H+2ogqRFsA6K4mrQtdIvzicFL0cNodjR4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ak131xBoMnRoyJentSKNY8Ucr4mQ6W/k77jz7dJ3+q+Cm98tXcA/mFJZYH04dC4bv Tziu9jdY7xA9AjNMFyoZ9MsMfdmiCKAylgbD6CBJ3t9d7GkGg+wlZ/3FmX1MKgbGWG zJdOmL3OIkPSk7f5bbMnEuu3o/eMzWW2CaXPAEG0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Petr Tesarik , Christoph Hellwig , Sasha Levin Subject: [PATCH 6.2 070/187] swiotlb: fix slot alignment checks Date: Mon, 3 Apr 2023 16:08:35 +0200 Message-Id: <20230403140418.250729553@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140416.015323160@linuxfoundation.org> References: <20230403140416.015323160@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Petr Tesarik [ Upstream commit 0eee5ae1025699ea93d44fdb6ef2365505082103 ] Explicit alignment and page alignment are used only to calculate the stride, not when checking actual slot physical address. Originally, only page alignment was implemented, and that worked, because the whole SWIOTLB is allocated on a page boundary, so aligning the start index was sufficient to ensure a page-aligned slot. When commit 1f221a0d0dbf ("swiotlb: respect min_align_mask") added support for min_align_mask, the index could be incremented in the search loop, potentially finding an unaligned slot if minimum device alignment is between IO_TLB_SIZE and PAGE_SIZE. The bug could go unnoticed, because the slot size is 2 KiB, and the most common page size is 4 KiB, so there is no alignment value in between. IIUC the intention has been to find a slot that conforms to all alignment constraints: device minimum alignment, an explicit alignment (given as function parameter) and optionally page alignment (if allocation size is >= PAGE_SIZE). The most restrictive mask can be trivially computed with logical AND. The rest can stay. Fixes: 1f221a0d0dbf ("swiotlb: respect min_align_mask") Fixes: e81e99bacc9f ("swiotlb: Support aligned swiotlb buffers") Signed-off-by: Petr Tesarik Signed-off-by: Christoph Hellwig Signed-off-by: Sasha Levin --- kernel/dma/swiotlb.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c index 869dd6667c464..312458506e6d5 100644 --- a/kernel/dma/swiotlb.c +++ b/kernel/dma/swiotlb.c @@ -642,22 +642,26 @@ static int swiotlb_do_find_slots(struct device *dev, int area_index, BUG_ON(!nslots); BUG_ON(area_index >= mem->nareas); + /* + * For allocations of PAGE_SIZE or larger only look for page aligned + * allocations. + */ + if (alloc_size >= PAGE_SIZE) + iotlb_align_mask &= PAGE_MASK; + iotlb_align_mask &= alloc_align_mask; + /* * For mappings with an alignment requirement don't bother looping to - * unaligned slots once we found an aligned one. For allocations of - * PAGE_SIZE or larger only look for page aligned allocations. + * unaligned slots once we found an aligned one. */ stride = (iotlb_align_mask >> IO_TLB_SHIFT) + 1; - if (alloc_size >= PAGE_SIZE) - stride = max(stride, stride << (PAGE_SHIFT - IO_TLB_SHIFT)); - stride = max(stride, (alloc_align_mask >> IO_TLB_SHIFT) + 1); spin_lock_irqsave(&area->lock, flags); if (unlikely(nslots > mem->area_nslabs - area->used)) goto not_found; slot_base = area_index * mem->area_nslabs; - index = wrap_area_index(mem, ALIGN(area->index, stride)); + index = area->index; for (slots_checked = 0; slots_checked < mem->area_nslabs; ) { slot_index = slot_base + index; -- 2.39.2