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 E90903019B2; Sun, 8 Feb 2026 02:03:15 +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=1770516196; cv=none; b=PKnxR6X+K8Sg1nnILyiR0AbQJk0ftEbjRtx+xnVjtAlbdoDCdbybxP1C/nEmZ7uWZjVk//L33QgbENgwCvemSCHvrfUWIsIawzEXikgbMivb3+pzkppfBF+OKdov5EZ85VZzUcfECK6hD5UAlAFI8VrqIhmckMDTGbEX7fzE8CY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770516196; c=relaxed/simple; bh=XQS4cY56FqK4LswF7/bdtC0K+2DFYFfTGsx9e6itWp4=; h=Date:To:From:Subject:Message-Id; b=MlJgYK3kPN0nvbEOmlR0p+dz4jfMhZchRSBpURa82N8b/RqyvuUI1ng61exq/whnI+iDFibQwnoAGMd5X4Pbtl5ZXTQRTKw/IelW7xilhpxr9RNnq44CX631L0T5AJ3z/pCNvgivM1V5LIBUUdhTlHr5w6FbrCPP4mTKdPDGkmA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=n3vNWNg9; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="n3vNWNg9" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6F444C19421; Sun, 8 Feb 2026 02:03:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1770516195; bh=XQS4cY56FqK4LswF7/bdtC0K+2DFYFfTGsx9e6itWp4=; h=Date:To:From:Subject:From; b=n3vNWNg9xq3zg347yOp73c/uKq1xA68lsI9m6pp1mVqsGhCSe6Xn5GivfmfQ5Wuon 5iBOOzgJ65D9d0yxS4M7aMyjM9BFGWFlwFf07vR7EBY1JzCkKa8vMFMa4ujGu+3Slb upduwlazESH5dR4EQZsX0PZBndQyNhqIaq15HZwA= Date: Sat, 07 Feb 2026 18:03:14 -0800 To: mm-commits@vger.kernel.org,ziy@nvidia.com,willy@infradead.org,vbabka@suse.cz,surenb@google.com,stable@vger.kernel.org,ryncsn@gmail.com,npiggin@gmail.com,mhocko@suse.com,jackmanb@google.com,hughd@google.com,hannes@cmpxchg.org,david@kernel.org,chrisl@kernel.org,mikhail.v.gavrilov@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-page_alloc-clear-page-private-in-free_pages_prepare.patch added to mm-unstable branch Message-Id: <20260208020315.6F444C19421@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/page_alloc: clear page->private in free_pages_prepare() has been added to the -mm mm-unstable branch. Its filename is mm-page_alloc-clear-page-private-in-free_pages_prepare.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-clear-page-private-in-free_pages_prepare.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Mikhail Gavrilov Subject: mm/page_alloc: clear page->private in free_pages_prepare() Date: Sat, 7 Feb 2026 22:36:14 +0500 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 Cc: Brendan Jackman Cc: Chris Li Cc: David Hildenbrand Cc: Hugh Dickins Cc: Johannes Weiner Cc: Kairui Song Cc: Matthew Wilcox (Oracle) Cc: Michal Hocko Cc: Nicholas Piggin Cc: Suren Baghdasaryan Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton --- mm/page_alloc.c | 1 + 1 file changed, 1 insertion(+) --- a/mm/page_alloc.c~mm-page_alloc-clear-page-private-in-free_pages_prepare +++ a/mm/page_alloc.c @@ -1429,6 +1429,7 @@ __always_inline bool free_pages_prepare( page_cpupid_reset_last(page); page->flags.f &= ~PAGE_FLAGS_CHECK_AT_PREP; + page->private = 0; reset_page_owner(page, order); page_table_check_free(page, order); pgalloc_tag_sub(page, 1 << order); _ Patches currently in -mm which might be from mikhail.v.gavrilov@gmail.com are mm-page_alloc-clear-page-private-in-free_pages_prepare.patch