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 D9A7A133987; Tue, 20 Feb 2024 21:12:44 +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=1708463564; cv=none; b=OcLYVhhZWRX0ZZZxcKf/3cT7EaEZkYq0ZBKgqvx/2lnyp6Q8nE4D9l7RpagaTg8FkYO/cAaaqXk3i8I2GWMZ0hfBXaQu2BjP1KzAWHqNeDcAeBn7nQMomS02ZyuLU6aYeRfUPs6hIKooMLbOqmM7soQA2Y7CK/sAGTpymhaBuZ4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708463564; c=relaxed/simple; bh=kjoHjK0USZu0tNWEtYkwKe0JMoTWQE2vKsgcaQUfRrI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=bI/5Bmgu/40iqvDdLPlYGe/nxdzh78dtOml8Slh48T/NyRuIdYUdOwTCI9xxjmJTvlsTq6htngot1iGCUZRf1LILaFgHOAfrnjncC3M+d73mZOD44fjbqWbBbCh0y0uXHx4OvFiTjH7nqaMfMT6AxgVQaHXw+poofgp+AY5Wops= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Hv9DoSr7; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Hv9DoSr7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D8CA2C433C7; Tue, 20 Feb 2024 21:12:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1708463564; bh=kjoHjK0USZu0tNWEtYkwKe0JMoTWQE2vKsgcaQUfRrI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Hv9DoSr7SZD9W01DKW46pPyY/KmrK3G4bw4I9skcnfykFDe2av+y5s4PKDTo9G25T J2Kqk4wdqODYKhlEl3+Uv4QlPaGqFX818IDDt3O3XQa4QfRCsa6bvwGzujuwmQy/Hj ZWzykOvWS774GiK+bwTGwUzrIbOpXQlvY4NtUPTE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lokesh Gidra , Andrea Arcangeli , Mike Rapoport , Axel Rasmussen , Brian Geffon , David Hildenbrand , Jann Horn , Kalesh Singh , "Matthew Wilcox (Oracle)" , Nicolas Geoffray , Peter Xu , Suren Baghdasaryan , Andrew Morton Subject: [PATCH 6.6 055/331] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb Date: Tue, 20 Feb 2024 21:52:51 +0100 Message-ID: <20240220205639.316922458@linuxfoundation.org> X-Mailer: git-send-email 2.43.2 In-Reply-To: <20240220205637.572693592@linuxfoundation.org> References: <20240220205637.572693592@linuxfoundation.org> User-Agent: quilt/0.67 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: Lokesh Gidra commit 67695f18d55924b2013534ef3bdc363bc9e14605 upstream. In mfill_atomic_hugetlb(), mmap_changing isn't being checked again if we drop mmap_lock and reacquire it. When the lock is not held, mmap_changing could have been incremented. This is also inconsistent with the behavior in mfill_atomic(). Link: https://lkml.kernel.org/r/20240117223729.1444522-1-lokeshgidra@google.com Fixes: df2cc96e77011 ("userfaultfd: prevent non-cooperative events vs mcopy_atomic races") Signed-off-by: Lokesh Gidra Cc: Andrea Arcangeli Cc: Mike Rapoport Cc: Axel Rasmussen Cc: Brian Geffon Cc: David Hildenbrand Cc: Jann Horn Cc: Kalesh Singh Cc: Matthew Wilcox (Oracle) Cc: Nicolas Geoffray Cc: Peter Xu Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- mm/userfaultfd.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -357,6 +357,7 @@ static __always_inline ssize_t mfill_ato unsigned long dst_start, unsigned long src_start, unsigned long len, + atomic_t *mmap_changing, uffd_flags_t flags) { struct mm_struct *dst_mm = dst_vma->vm_mm; @@ -472,6 +473,15 @@ retry: goto out; } mmap_read_lock(dst_mm); + /* + * If memory mappings are changing because of non-cooperative + * operation (e.g. mremap) running in parallel, bail out and + * request the user to retry later + */ + if (mmap_changing && atomic_read(mmap_changing)) { + err = -EAGAIN; + break; + } dst_vma = NULL; goto retry; @@ -506,6 +516,7 @@ extern ssize_t mfill_atomic_hugetlb(stru unsigned long dst_start, unsigned long src_start, unsigned long len, + atomic_t *mmap_changing, uffd_flags_t flags); #endif /* CONFIG_HUGETLB_PAGE */ @@ -622,8 +633,8 @@ retry: * If this is a HUGETLB vma, pass off to appropriate routine */ if (is_vm_hugetlb_page(dst_vma)) - return mfill_atomic_hugetlb(dst_vma, dst_start, - src_start, len, flags); + return mfill_atomic_hugetlb(dst_vma, dst_start, src_start, + len, mmap_changing, flags); if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock;