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 D0FA139FF8 for ; Mon, 19 Feb 2024 15:28:16 +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=1708356496; cv=none; b=C8BVP01UfPX7CFRio9GLCXwT0KkLz/ul1RJLq61Vk7nbzEpN88mLBfoZVam6Hs2sv6qlJw3YUCLZYqzjXgaw58M8+SywYauNB4VR3pGblmK3UBwp1KuAhT+Tlrok8Oj3ZZoTjJwVcaybXQNrSrM078fEVSfRfHWoTBhEhjRAcGU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708356496; c=relaxed/simple; bh=pL3E7InpGvGpfwpJ3VmC0F5xokOAzwxW74bTS3/77v0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KptqdLYvwTMkaPGRZe+8DrYf115UufYjer0UEXWyug4IYjiNDepFID8D5d5teu+MJUrj4K9dXopWyhwcwBLdH2oHuynXpgboEX5+hyyIt4zHa91VWZIcasNaGCK/0zR+9hDGJSD4LGyWpQ/l7p4+TP1bAEWrutAfDnm3YWqIwcE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Gaa2RDA7; 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="Gaa2RDA7" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF584C433C7; Mon, 19 Feb 2024 15:28:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708356496; bh=pL3E7InpGvGpfwpJ3VmC0F5xokOAzwxW74bTS3/77v0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Gaa2RDA7NOiizGldOwGaO0py+5J9vPs6bHdUbp4Xz18TfnPUVclSFmABgvu0GjjRq 1fMXBmebmMwH4Pg/PNRIqU43syQ+zq2xnlusV/8BgjJRqTUNwf3AqfBMYFafzb4NlN ql8WID4ekegqg0mA1EjGEEnap+3dNOUZwI2VjetlLssI6DeB1D2IP05odMs0pFGG2X 0W+ZuioycZrGs8z3f9nrfP8BrWZH01iC3QE3LO49hNGna96LHxfdN7IhwYZxpxrr1x cl9/ZbrDCRMXGpztzvL8Y1nrzbAPyvtFvzBwiYdpO7mVaEqmytq2HND1HZoGgBJr47 bpY8BYRUYbO9w== 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 5.4.y"] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb Date: Mon, 19 Feb 2024 17:28:02 +0200 Message-ID: <20240219152802.394860-1-rppt@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <2024021850-vaseline-mongrel-489e@gregkh> References: <2024021850-vaseline-mongrel-489e@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 | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/mm/userfaultfd.c b/mm/userfaultfd.c index 6fa66e2111ea..e8758304a9f3 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -177,6 +177,7 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, + bool *mmap_changing, bool zeropage) { int vm_alloc_shared = dst_vma->vm_flags & VM_SHARED; @@ -308,6 +309,15 @@ static __always_inline ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, 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; @@ -389,6 +399,7 @@ extern ssize_t __mcopy_atomic_hugetlb(struct mm_struct *dst_mm, unsigned long dst_start, unsigned long src_start, unsigned long len, + bool *mmap_changing, bool zeropage); #endif /* CONFIG_HUGETLB_PAGE */ @@ -506,7 +517,8 @@ 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, zeropage); + src_start, len, mmap_changing, + zeropage); if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock; -- 2.43.0