From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1D19D2F745E; Tue, 16 Jun 2026 16:44:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781628265; cv=none; b=dNdI5Xp5MYFx5ypt8Lb1kvvR9QtnnSifxrnGnQ8bEK6KyBy4NUUEDPCtzbizs2y9Zsu8/QCuaTdVkEVnnUXAgo7XdLe7bCq2ZgfdJP+lP7MV99ETNGRUHmm7+KX2vmfXV5RTLmpbKOP5Kr6s91DbOj1G2/OA0CBsIWVLrayUNMQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781628265; c=relaxed/simple; bh=8oFxNnN0xYp9R0Beqzj1BnTf7UV4+zYQcgZ3mefpYvA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=C4Oln/AfNSQ5bRtMpbP52+SCLE/Z9OHC55Oqyq5cT8gG0t36NZkxaKMhOpM8bvt9hf3GYgqacO+j+I68UjbD5v7IPbIgWD2cEiIDdjbCeWHg82PQ3fcsEWVDVycKitwTN7jBnWv4k/N48LPj4DACKXKRrZ8L29Ldb0QJMOj02Z0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=EHAtZKP0; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="EHAtZKP0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D34971F000E9; Tue, 16 Jun 2026 16:44:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1781628264; bh=Z5ceESlV3BDh+VjrYtvU5Qikpbwh5gBdID0dfwJShHE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=EHAtZKP03ZeQb8SR+KORoBc3i/VgsDr3U7JBH7SH98HyVnVrfrIdMx0vDc5vA86bs OS339HIkvaUSCqebBKLCbCmKyaDszIEaa0J4kR5YueCqUCxj0g1L55CeMkE6piX/r4 Dnrn8f/MaUFpBM6fKGFOfBKB/7XA24Z7bO+6P5bM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Mikhail Gavrilov , Zi Yan , "David Hildenbrand (Arm)" , Vlastimil Babka , Brendan Jackman , Chris Li , Hugh Dickins , Johannes Weiner , Kairui Song , "Matthew Wilcox (Oracle)" , Michal Hocko , Nicholas Piggin , Suren Baghdasaryan , Andrew Morton , Li Wang , Sasha Levin Subject: [PATCH 6.6 062/452] mm/page_alloc: clear page->private in free_pages_prepare() Date: Tue, 16 Jun 2026 20:24:49 +0530 Message-ID: <20260616145121.213065682@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260616145117.796205997@linuxfoundation.org> References: <20260616145117.796205997@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikhail Gavrilov [ Upstream commit ac1ea219590c09572ed5992dc233bbf7bb70fef9 ] 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. Link: https://lkml.kernel.org/r/20260207173615.146159-1-mikhail.v.gavrilov@gmail.com Fixes: 3b8000ae185c ("mm/vmalloc: huge vmalloc backing pages should be split rather than compound") Signed-off-by: Mikhail Gavrilov Suggested-by: Zi Yan Acked-by: Zi Yan Acked-by: David Hildenbrand (Arm) Reviewed-by: Vlastimil Babka Cc: Brendan Jackman Cc: Chris Li Cc: Hugh Dickins Cc: Johannes Weiner Cc: Kairui Song Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Nicholas Piggin Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton [backport: context only] Signed-off-by: Li Wang Signed-off-by: Sasha Levin --- mm/page_alloc.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index b617fb364b15d1..ffdc71103c2ad2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1178,6 +1178,7 @@ static __always_inline bool free_pages_prepare(struct page *page, page_cpupid_reset_last(page); page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP; + page->private = 0; reset_page_owner(page, order); page_table_check_free(page, order); -- 2.53.0