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 7B8651D6193; Mon, 9 Feb 2026 19:46:13 +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=1770666373; cv=none; b=Bm6hapTabpxxsTwghWy30WxP6QLGzGNLOL+9ayrU4F6dqMAgBdaZYlRpKXrUPqekXlGK7dJBugIQxYN0g8Ipmur7Jh3FwOMAd8cuwcznDEDKLfMV3DKD4c77g8PXCoF3xWLJ/7mskL95D5OzGJ0v6SigAuAGkZbcmie/ZR9ZVCU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770666373; c=relaxed/simple; bh=NjsLfTgcSHxbInEjowlv0DjeZPoEztoNp3YDgwdnlf0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=eoiPxVoh8MDnmM4bSzjt+iMnbJnDH15F5DSle7hGcXEnhpv2dzscg53josUPETWTMfzYvy8B1mt/5BsSP/8uF4WQsjQTbGWS1KD/4Ss/g749eCYf6u+Ip2BRyJrXAX7x+5+7qdcDhDLIIUzvniHs5VK40FbM6FAOufg6Zg0HqCM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=tNizQ9Cz; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="tNizQ9Cz" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8C501C116C6; Mon, 9 Feb 2026 19:46:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1770666373; bh=NjsLfTgcSHxbInEjowlv0DjeZPoEztoNp3YDgwdnlf0=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=tNizQ9Cz4zFrx+Aab+u/InMxiwoNYZQGZz/rYK7u+uYTkpwHGi7dHkFVAGf0CkQJ0 Y8pRjFcAzj95DJOxx98TxAdIe0sHJtASEgP572Tz+UX/FecRBmhr4A9a739ETiTn3c SVIcJ9OO6PKVjKcG4W/LWHhqifgSOIHCEBl74venwHcvXb7AVhvQHwLZnnq0t+gAFW /MQ89ixqGCp/z8pwiqGRE1YryoI9ddd5OJv5pk1VQ+66gS+9XfWQM4NhoibsItxduS sCnuOjo7wCq0YaLBM46NZf6Zbfb79/Dc4814+MZkNATA0bfUMhfMlBU1xhxn1LqLxr UqRQbPqmhFYvA== Message-ID: <7e86e2f0-e581-4772-b468-1da04a214f07@kernel.org> Date: Mon, 9 Feb 2026 20:46:06 +0100 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/page_alloc: clear page->private in free_pages_prepare() To: Mikhail Gavrilov , linux-mm@kvack.org Cc: akpm@linux-foundation.org, vbabka@suse.cz, surenb@google.com, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, npiggin@gmail.com, linux-kernel@vger.kernel.org, kasong@tencent.com, hughd@google.com, chrisl@kernel.org, ryncsn@gmail.com, stable@vger.kernel.org, willy@infradead.org References: <209207FE-D3A9-4BE2-8DA7-9BE38A19F387@nvidia.com> <20260207173615.146159-1-mikhail.v.gavrilov@gmail.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2/7/26 18:36, Mikhail Gavrilov wrote: > Several subsystems (slub, shmem, ttm, etc.) use page->private but don't > clear it before freeing pages. When these pages are later allocated as > high-order pages and split via split_page(), tail pages retain stale > page->private values. > > This causes a use-after-free in the swap subsystem. The swap code uses > page->private to track swap count continuations, assuming freshly > allocated pages have page->private == 0. When stale values are present, > swap_count_continued() incorrectly assumes the continuation list is valid > and iterates over uninitialized page->lru containing LIST_POISON values, > causing a crash: > > KASAN: maybe wild-memory-access in range [0xdead000000000100-0xdead000000000107] > RIP: 0010:__do_sys_swapoff+0x1151/0x1860 > > Fix this by clearing page->private in free_pages_prepare(), ensuring all > freed pages have clean state regardless of previous use. > > Fixes: 3b8000ae185c ("mm/vmalloc: huge vmalloc backing pages should be split rather than compound") > Cc: stable@vger.kernel.org > Suggested-by: Zi Yan > Acked-by: Zi Yan > Signed-off-by: Mikhail Gavrilov > --- Okay, let's do this as a fix, and cleanup the page->private handling separately. Thanks! Acked-by: David Hildenbrand (Arm) -- Cheers, David