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 4013D3839B for ; Mon, 19 Feb 2024 15:25:15 +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=1708356315; cv=none; b=Sh5zhAqI7CdjQV+qvDu249kkMJIB6F5xBF1bDeGElNcOmOhev93TuZBSrSC1KKe+IzA7ogecTPUV+IbSXT2JEoDmaeUkRuSDmsIOn0wju4Tj8BQn7UzLEGRy9mJzbUyQvhifA9hTqrAEWk3WDaKpYANEpLnQ2FTrUFr+jbVQLS0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708356315; c=relaxed/simple; bh=XMAwhd513OzrWbhqYszqwzRJS4HKcTdTYX2ZXufpADo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=h5U37ziQ7vqYXQDZCY8mLs1e0pzQ2fx1VTCJVI/jhtCEamnRiScGYZa0nK8X7CeM8kh2Btg4YMp6+OAdEJFojVMr8NMJwvMCc/IJw3UTvhRaCenrA1TlG4NVrlgq/Fr7v4OZGw4AzF7zp0VJmTj8UmSCY5QgL6NcXRP9RizWatE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=bM8mFs/c; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="bM8mFs/c" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 70C30C433C7; Mon, 19 Feb 2024 15:25:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708356315; bh=XMAwhd513OzrWbhqYszqwzRJS4HKcTdTYX2ZXufpADo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bM8mFs/chvnd/DZJrVp4awMxRtTndENIQ/NB5+9l2mW5+j6jHY95dfPoQftccX+rF 9Qu/MkuWXBjcqvDvIb41qqEz/jKZeVfAzKkJrUPGnOpygLg0diFneq3Aejx68PBAmy BylNhrc2igJwbfyuq2JLQBiFkMjgabtB47h+AF9o/pFCruaNXNBnVsYpSAqie4G6Fs Y97oxEuLkQO0QO8Evm+6uiIH2th0bdl40jL6kock58yEfqF8VqIZSrUJeRDF8ibUxY JL8P6ZX7fnVK6Ga9ccl87vV8GkfX5PdPJ7iedbv9TUIzQ8kiBCHVLlvf0UQADZqbCM W6h2KtINucuCQ== From: Mike Rapoport To: stable@vger.kernel.org Cc: Lokesh Gidra , Andrea Arcangeli , Mike Rapoport , Axel Rasmussen , Brian Geffon , David Hildenbrand , Jann Horn , Kalesh Singh , Matthew Wilcox , Nicolas Geoffray , Peter Xu , Suren Baghdasaryan , Andrew Morton Subject: ["PATCH 6.1.y"] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb Date: Mon, 19 Feb 2024 17:24:52 +0200 Message-ID: <20240219152452.394767-1-rppt@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <2024021847-glandular-distant-2033@gregkh> References: <2024021847-glandular-distant-2033@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Lokesh Gidra 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 (cherry picked from commit 67695f18d55924b2013534ef3bdc363bc9e14605) Signed-off-by: Mike Rapoport (IBM) --- mm/userfaultfd.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 650ab6cfd5f4..992a0a16846f 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -327,6 +327,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, + atomic_t *mmap_changing, enum mcopy_atomic_mode mode, bool wp_copy) { @@ -445,6 +446,15 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 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; @@ -480,6 +490,7 @@ extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, + atomic_t *mmap_changing, enum mcopy_atomic_mode mode, bool wp_copy); #endif /* CONFIG_HUGETLB_PAGE */ @@ -601,8 +612,8 @@ static __always_inline ssize_t __mcopy_atomic(struct mm_struct *dst_mm, */ if (is_vm_hugetlb_page(dst_vma)) return __mcopy_atomic_hugetlb(dst_mm, dst_vma, dst_start, - src_start, len, mcopy_mode, - wp_copy); + src_start, len, mmap_changing, + mcopy_mode, wp_copy); if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock; -- 2.43.0