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 03E533B7A8 for ; Mon, 19 Feb 2024 15:34:22 +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=1708356863; cv=none; b=QY2OVtnWkEofDoIjyl0f+bfYwww0k9N7CixiN+ZWhAAJrlUmU7hdpSIzI2NVq/+gtrpNw2Cli9jNBBX1mqMiXJG3dYglXEU/Qv9O1/r8Ye2WnjjCjt+7G/I7qQoyZvFKws1wkYe9cdnhsDFzb2zE1oHszUaxI020vi2m+N/KDEw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1708356863; c=relaxed/simple; bh=z3EqET8v1SV8aKhSUNdapck2hOxe0BnbNbCi36QArjk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QtCaVmyRMcSyaE1XTiT1vxwGVXQmPmdApXCVtdxl2X7vAccwXH2jnPleRRXrqVxA5pNLeYA2bwhAQoU5Q9EtkYaaqcCL/HSCftVrGGzMTi72E8TaS7IP48WPWiFUDrMHbnW7vtvEGZasSX4H0sM9Qeamh+ZqQuMvHYNq27l/ujE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=n9FZu9/h; 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="n9FZu9/h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E19ABC433B1; Mon, 19 Feb 2024 15:34:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1708356862; bh=z3EqET8v1SV8aKhSUNdapck2hOxe0BnbNbCi36QArjk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=n9FZu9/hu+mG7gvac8URYyfzEs8w0jMiuKsfLHIDEyfwF62xxApGj8FTHEFfTrZAu E9BJcdO6Kfw+OQbeFuv2H7gY8iSxGPxSjrAuOglh8qk8fIYC1pXS/JkibyvcPS3nk7 aSiWIflo6bE2JNFFj7QDLOdy0LfWKCwbb1OBVF7g+k7b3ssG+bm3OcT1SpfPMr4fXr pLbzG+SVOhNGzM/ucMB4q+maQ+6QGDeRoTf7vzUHyCW56mHrWHQ1/Pe7O1xsR6lxpT rxSDEQeSPpEsPUY8GDOk0dJ1fAEuCb3b79HRamQDvOCwnsCqFGRSU7fR8isF8HCrBY fB9g42FNNrBQg== 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 4.19.y] userfaultfd: fix mmap_changing checking in mfill_atomic_hugetlb Date: Mon, 19 Feb 2024 17:34:01 +0200 Message-ID: <20240219153401.397328-1-rppt@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <2024021851-implement-sulfide-c5fa@gregkh> References: <2024021851-implement-sulfide-c5fa@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 aae19c29bcfa..dcca7788222a 100644 --- a/mm/userfaultfd.c +++ b/mm/userfaultfd.c @@ -179,6 +179,7 @@ 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; @@ -310,6 +311,15 @@ 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; @@ -391,6 +401,7 @@ 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 */ @@ -508,7 +519,8 @@ 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