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 1B9BD1EA80 for ; Mon, 19 Feb 2024 15:26:05 +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=1708356366; cv=none; b=NEF17fmRXDl11lXbTDBEgMFZvZu9xz+SxLid/EMFPXHO4NOfQMEE5YBcN7H36kJrRgZq5HXYT66N6RSF9Nzlqh4wlDI2FeVXJy74aImO5M0mJmzl+T3XnvPt2GtblcveFgh9wLJ4Pv4f4NFMy5pus2rwDzihTJD7RwRFMeFuIOw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708356366; c=relaxed/simple; bh=zL3299zTVnK2hz7DI4UAzlgM3bvr4vtxM8b4CuPIUkg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=f1WBgpuzsp2RvY7t324FRXGvgtAi6dw06/2+YrSgw2MYKKv0RefdcE3iutgbmy+jOHT39AV+19to0vaHGx8npMH++a7k7De8MfR4AMkRi3zXG23X4cZK7Xp7g9+GoaXpOjC0ZfEzdYzq74YZ7YVRdr9S+ldLBaw1IZG93YOO4tQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NhmJL0Zp; 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="NhmJL0Zp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E04D2C433F1; Mon, 19 Feb 2024 15:26:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708356365; bh=zL3299zTVnK2hz7DI4UAzlgM3bvr4vtxM8b4CuPIUkg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NhmJL0ZpnEXRq4Y+5Xt03bum30eQxASc+T+VIzy8ynZm/119grXYyf4JYJtsRh58W xGkTZOSi1BJaIE96UWMcf+H0pubgWsIkXFPefn9X6eV9JUtgTsKCmvDfnsivCqyXWj HPtzYsUBdU9B0On88OAkH0Uc7/4GNIWbjSqbMIfn9WcjVLsHp/HdiabnxMJbZD6sEe 2dFOZpKsIqb0QW65WCLELtUXo+dvrbkxzW9+ZxzZKAf8/kM/l0K4WRvosQRhkb75h+ 0KTdp6IQCJzou50bscBGfisjeiFqRXkp0JHC9fhWBUGTNyXoil3um0A5XUtaI3Kxed LYmqWwxKqOXEg== 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 5.15.y"] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb Date: Mon, 19 Feb 2024 17:25:51 +0200 Message-ID: <20240219152551.394793-1-rppt@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <2024021848-spiny-glitzy-711f@gregkh> References: <2024021848-spiny-glitzy-711f@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 caa13abe0c56..98a9d0ef2d91 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -289,6 +289,7 @@ 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) { int vm_shared = dst_vma->vm_flags & VM_SHARED; @@ -405,6 +406,15 @@ 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; @@ -440,6 +450,7 @@ 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); #endif /* CONFIG_HUGETLB_PAGE */ @@ -561,7 +572,8 @@ 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); + src_start, len, mmap_changing, + mcopy_mode); if (!vma_is_anonymous(dst_vma) && !vma_is_shmem(dst_vma)) goto out_unlock; -- 2.43.0