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 4287A13EFE4; Tue, 27 Feb 2024 13:45:26 +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=1709041526; cv=none; b=fKIPxo6c1DMl48DSrLXUu+YERA2lQN06d7OHEVUCBqaKmRNHqyyie7O45COisp1dXSia6fc8OdaLbq55WPvq0QUl5eXaM2YRZEX1qY3tGv9ApU+bp4rUgnUSAaR5uYIPsAJvrUJ93CintMl3PSq71BFXE4gR2aJkPD52fWdri4A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709041526; c=relaxed/simple; bh=ryuRZcHNWj0XjxsvCAWgoYFgnyOimq+2e+u4fPa2hko=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YTupAe+uAMZWfUGa6Fto79IYjOwzorKekKZz2ndSVtsm71WHllmebd1MtQx8WNsxQYCOdybFxLt6HMVPQsdhB+HG8KCUajuLh6hXMLZv0xilaMrDL2xEjZWmz8ZqHcDbtM9TW2rRk2TNCk39pgs89CAYVP12C7vSdnw7p5ymsHs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=gfvrwuXp; 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="gfvrwuXp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9689DC433C7; Tue, 27 Feb 2024 13:45:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1709041526; bh=ryuRZcHNWj0XjxsvCAWgoYFgnyOimq+2e+u4fPa2hko=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gfvrwuXpAu6YzKUZRPoN3K1iWTKaIxUYU5Iq/8KTYSFRfxuVbjI8esJQPBfgdvGSu j9cBg6u1vZLWaMhuWDkFgM7QyYbbNvoqKeK1V9WgthxyE51sQ1JpZC0N49iIBxcjMq Z74SQtYxbtUt1Ov5H5Kt/EiffUAVLlrnAoBxTEMo= 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 4.19 08/52] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb Date: Tue, 27 Feb 2024 14:25:55 +0100 Message-ID: <20240227131548.806329212@linuxfoundation.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240227131548.514622258@linuxfoundation.org> References: <20240227131548.514622258@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 4.19-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: Mike Rapoport (IBM) Signed-off-by: Greg Kroah-Hartman --- mm/userfaultfd.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -179,6 +179,7 @@ static __always_inline ssize_t __mcopy_a unsigned long dst_start, unsigned long src_start, unsigned long len, + bool *mmap_changing, bool zeropage) { int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; @@ -310,6 +311,15 @@ retry: goto out; } down_read(&dst_mm->mmap_sem); + /* + * 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 && READ_ONCE(*mmap_changing)) { + err = -EAGAIN; + break; + } dst_vma = NULL; goto retry; @@ -391,6 +401,7 @@ extern ssize_t __mcopy_atomic_hugetlb(st unsigned long dst_start, unsigned long src_start, unsigned long len, + bool *mmap_changing, bool zeropage); #endif /* CONFIG_HUGETLB_PAGE */ @@ -508,7 +519,8 @@ retry: */ if (is_vm_hugetlb_page(dst_vma)) return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, - src_start, len, zeropage); + src_start, len, mmap_changing, + zeropage); if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock;