From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793827174; b=NcTi9iDM/FL/f92wDCmN2cTg2KrdMcAvyeEV0z9doSroRrcUqpe8QJR0J4KSeV0QHGWD 4Fe1x4EUC7E2bzt0X6QEMF2PlORP+aqbahBlIk2p3BfugTrTCW+3AkoxnupFhaTGa9ojV E9nN6PnuwB9z9KBcVIbVAEdIQrJH2WOSiyBmyVwCLSXq2+RvuqEPbJK61q6+MMfJC3oSs csEJ40rpZB+8ejx0FT9S9dOgBpqq30UQvfkckh5xAoBXQGoRcedPzfqLVqev9tBHe9oKS 4eCsxozlj6ttT4nh2CNMEW5N/qFL2YaU1WVSAUFqrO/Y05UXmAa7hl+MsoYDf2gF1+A== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793827174; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=QQiPQX9D5x8UF9T9cGNFz+PdDa49FkYHpGLrl3WKXo4=; b=CR8nWQH5IstnHspgCgtM1ZCfN1xF47xcNqqD7j3WBlH40glrOjs4f1eEgJtphqij2CMS 8fKac6fuXPMilPNyZUNOOb6Yoe08uB+A0qczdqV5RT9PHfU5Ls7yVKEDLIiDMVytEHHqk ou9dbngXyPga4C4z1hgSgvtjhIcQNpzHomTOClQlqZyawryFZ/siUn9o/1Swh5D4q5eyW COxOvPXpROBO3NPxf3NEDG3rleo7zGpSez3h8zkuvHuNnfD/hJB2jEAOUo2hTumzK/AsQ /mO7hwKlzwtdFmsO9lbYcaCxGqBvJe/h/t48pISm10PR1if694m1oumEat7JvhSSs6Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=VHXVOwm9; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1A83C6074FA1; Wed, 4 Nov 2026 21:19:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=VHXVOwm9 Received: by smtp.kernel.org (Postfix) with ESMTPSA id 708FD1F00A02; Wed, 4 Nov 2026 21:19:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793827169; bh=QQiPQX9D5x8UF9T9cGNFz+PdDa49FkYHpGLrl3WKXo4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=VHXVOwm9RZFV1sG+sdjsyeVtHlrpyiOajNWdu+V7YW4QOaWvJ338BsbCRVz4yfT41 IFbmpQdyHJk4h0RSbDhcrn7AHB4SGTXinsIKY236UUfqAGxdqtyapy4XmM7qQd6cFE MIi7iqsSEqNy2kx2AxeKRb8ukttPhoR2wxYrsmuw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Vernon Yang , Andrew Morton , "David Hildenbrand (Arm)" , "Lorenzo Stoakes (ARM)" , Barry Song , Dev Jain , Lance Yang , Ryan Roberts , Zach OKeefe Subject: [PATCH 7.3 236/547] mm: khugepaged: fix folio is used after folio_put/unlock() Date: Wed, 4 Nov 2026 16:07:00 -0500 Message-ID: <20261104211044.868021283@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211038.406938024@linuxfoundation.org> References: <20261104211038.406938024@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Vernon Yang commit 9010383e71e6ce75fcd3c8f87133c8ce6c0e6ab4 upstream. On the rollback path, folio_put() has already dropped the last reference of new_folio. On the success path, new_folio is already unlocked and can be freed concurrently. The trace_mm_khugepaged_collapse_file() is left with a dangling folio pointer. So using the folio_pfn() before dropping the reference, closing use-after-free window. Link: https://lore.kernel.org/20260909025804.3233645-4-vernon2gm@gmail.com Fixes: 4c9473e87e75 ("mm/khugepaged: add tracepoint to collapse_file()") Signed-off-by: Vernon Yang Signed-off-by: Andrew Morton Acked-by: David Hildenbrand (Arm) Acked-by: Lorenzo Stoakes (ARM) Cc: Barry Song Cc: Dev Jain Cc: Lance Yang Cc: Ryan Roberts Cc: Zach O'Keefe Cc: Signed-off-by: Greg Kroah-Hartman --- include/trace/events/huge_memory.h | 6 +++--- mm/khugepaged.c | 4 +++- 2 files changed, 6 insertions(+), 4 deletions(-) --- a/include/trace/events/huge_memory.h +++ b/include/trace/events/huge_memory.h @@ -211,10 +211,10 @@ TRACE_EVENT(mm_khugepaged_scan_file, ); TRACE_EVENT(mm_khugepaged_collapse_file, - TP_PROTO(struct mm_struct *mm, struct folio *new_folio, pgoff_t index, + TP_PROTO(struct mm_struct *mm, unsigned long new_pfn, pgoff_t index, unsigned long addr, bool is_shmem, struct file *file, int nr, int result), - TP_ARGS(mm, new_folio, index, addr, is_shmem, file, nr, result), + TP_ARGS(mm, new_pfn, index, addr, is_shmem, file, nr, result), TP_STRUCT__entry( __field(struct mm_struct *, mm) __field(unsigned long, hpfn) @@ -228,7 +228,7 @@ TRACE_EVENT(mm_khugepaged_collapse_file, TP_fast_assign( __entry->mm = mm; - __entry->hpfn = new_folio ? folio_pfn(new_folio) : -1; + __entry->hpfn = new_pfn; __entry->index = index; __entry->addr = addr; __entry->is_shmem = is_shmem; --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -2245,6 +2245,7 @@ static enum scan_result collapse_file(st struct address_space *mapping = file->f_mapping; struct page *dst; struct folio *folio, *tmp, *new_folio; + unsigned long new_pfn = -1; pgoff_t index = 0, end = start + HPAGE_PMD_NR; LIST_HEAD(pagelist); XA_STATE_ORDER(xas, &mapping->i_pages, start, HPAGE_PMD_ORDER); @@ -2264,6 +2265,7 @@ static enum scan_result collapse_file(st result = alloc_charge_folio(&new_folio, mm, cc, HPAGE_PMD_ORDER); if (result != SCAN_SUCCEED) goto out; + new_pfn = folio_pfn(new_folio); mapping_set_update(&xas, mapping); @@ -2667,7 +2669,7 @@ rollback: folio_put(new_folio); out: VM_BUG_ON(!list_empty(&pagelist)); - trace_mm_khugepaged_collapse_file(mm, new_folio, index, addr, is_shmem, file, HPAGE_PMD_NR, result); + trace_mm_khugepaged_collapse_file(mm, new_pfn, index, addr, is_shmem, file, HPAGE_PMD_NR, result); return result; }