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 0AC313988F9; Mon, 27 Apr 2026 07:49:53 +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=1777276194; cv=none; b=Ny7WQuR5OxAbZoHdzevlr0ok4SnvB+1/o45JGJGHNIdqwnO2Jtc2AsErjy3kolshpUgET9CBpyk5DR9rPAiL9VOEpbQc3uyh+anYbpw1KU0jv3kA6dRS3aeYy/FU8cPcFshz6CD5qOVEW4WwV6Jl9Oy6y81187CaHwwLqJjWkqo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777276194; c=relaxed/simple; bh=8PAx/Lj/i0A7i3Xe8MtXIluINnIK7hkHmrHp0hfdwsM=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=gSCiqyQ18iDKWekRpBLCWelcSjO2W+Hu01CSrYumWrgyeT38IZT21KTHIuHKQqnsDZZlhKtuLp9Ihip7Sw3O3YjX5O/+dP6yVj+IbtzOgy66C42C+eWFv7QRNH+svz7dbVU6cMNkvHisKqsMWaCs1sIFaSUVq9J3+q0oJzmuNMo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=SPJ6hkYf; 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="SPJ6hkYf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1921DC19425; Mon, 27 Apr 2026 07:49:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777276193; bh=8PAx/Lj/i0A7i3Xe8MtXIluINnIK7hkHmrHp0hfdwsM=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=SPJ6hkYfzN+5b4CnLo73B7aefn99CtQpDhkPueDg+mQloUliBGWOb/Xrp00C7QNdp S7HMxRBB+228JCvtKo4IeL9TXUdavserDjkvSzEZT2goKRjEpwMGUXdJJLN/ssXWM1 40Svp9zP3dXZlHl7tRBWhk263pDl3h43ONP8u9c0XLAjit8AXW45sAMS1IJ4A9gRjg MmC5WGSNb3sTuIvNgRPxL0pU2CoZEGsyMMrFbNc5Cj5eeEFIUiIKB/KDB1BQXRGpnj xubxSKqDA8DfAdMUjz6vMEYXkuONh4km4VVYPU7CkCNjjKx+2RBkt2OSpISWCz/00Q iR1LlxwoHjP2A== Message-ID: <40a48a9a-57d6-4658-89a0-68891b5bda99@kernel.org> Date: Mon, 27 Apr 2026 09:49:46 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] mm/madvise: reject invalid process_madvise() advice for zero-length vectors To: fujunjie , Andrew Morton Cc: "Liam R . Howlett" , Lorenzo Stoakes , Vlastimil Babka , Jann Horn , Shuah Khan , Christian Brauner , SeongJae Park , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org References: From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; keydata= xsFNBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABzS5EYXZpZCBIaWxk ZW5icmFuZCAoQ3VycmVudCkgPGRhdmlkQGtlcm5lbC5vcmc+wsGQBBMBCAA6AhsDBQkmWAik AgsJBBUKCQgCFgICHgUCF4AWIQQb2cqtc1xMOkYN/MpN3hD3AP+DWgUCaYJt/AIZAQAKCRBN 3hD3AP+DWriiD/9BLGEKG+N8L2AXhikJg6YmXom9ytRwPqDgpHpVg2xdhopoWdMRXjzOrIKD g4LSnFaKneQD0hZhoArEeamG5tyo32xoRsPwkbpIzL0OKSZ8G6mVbFGpjmyDLQCAxteXCLXz ZI0VbsuJKelYnKcXWOIndOrNRvE5eoOfTt2XfBnAapxMYY2IsV+qaUXlO63GgfIOg8RBaj7x 3NxkI3rV0SHhI4GU9K6jCvGghxeS1QX6L/XI9mfAYaIwGy5B68kF26piAVYv/QZDEVIpo3t7 /fjSpxKT8plJH6rhhR0epy8dWRHk3qT5tk2P85twasdloWtkMZ7FsCJRKWscm1BLpsDn6EQ4 jeMHECiY9kGKKi8dQpv3FRyo2QApZ49NNDbwcR0ZndK0XFo15iH708H5Qja/8TuXCwnPWAcJ DQoNIDFyaxe26Rx3ZwUkRALa3iPcVjE0//TrQ4KnFf+lMBSrS33xDDBfevW9+Dk6IISmDH1R HFq2jpkN+FX/PE8eVhV68B2DsAPZ5rUwyCKUXPTJ/irrCCmAAb5Jpv11S7hUSpqtM/6oVESC 3z/7CzrVtRODzLtNgV4r5EI+wAv/3PgJLlMwgJM90Fb3CB2IgbxhjvmB1WNdvXACVydx55V7 LPPKodSTF29rlnQAf9HLgCphuuSrrPn5VQDaYZl4N/7zc2wcWM7BTQRVy5+RARAA59fefSDR 9nMGCb9LbMX+TFAoIQo/wgP5XPyzLYakO+94GrgfZjfhdaxPXMsl2+o8jhp/hlIzG56taNdt VZtPp3ih1AgbR8rHgXw1xwOpuAd5lE1qNd54ndHuADO9a9A0vPimIes78Hi1/yy+ZEEvRkHk /kDa6F3AtTc1m4rbbOk2fiKzzsE9YXweFjQvl9p+AMw6qd/iC4lUk9g0+FQXNdRs+o4o6Qvy iOQJfGQ4UcBuOy1IrkJrd8qq5jet1fcM2j4QvsW8CLDWZS1L7kZ5gT5EycMKxUWb8LuRjxzZ 3QY1aQH2kkzn6acigU3HLtgFyV1gBNV44ehjgvJpRY2cC8VhanTx0dZ9mj1YKIky5N+C0f21 zvntBqcxV0+3p8MrxRRcgEtDZNav+xAoT3G0W4SahAaUTWXpsZoOecwtxi74CyneQNPTDjNg azHmvpdBVEfj7k3p4dmJp5i0U66Onmf6mMFpArvBRSMOKU9DlAzMi4IvhiNWjKVaIE2Se9BY FdKVAJaZq85P2y20ZBd08ILnKcj7XKZkLU5FkoA0udEBvQ0f9QLNyyy3DZMCQWcwRuj1m73D sq8DEFBdZ5eEkj1dCyx+t/ga6x2rHyc8Sl86oK1tvAkwBNsfKou3v+jP/l14a7DGBvrmlYjO 59o3t6inu6H7pt7OL6u6BQj7DoMAEQEAAcLBfAQYAQgAJgIbDBYhBBvZyq1zXEw6Rg38yk3e EPcA/4NaBQJonNqrBQkmWAihAAoJEE3eEPcA/4NaKtMQALAJ8PzprBEXbXcEXwDKQu+P/vts IfUb1UNMfMV76BicGa5NCZnJNQASDP/+bFg6O3gx5NbhHHPeaWz/VxlOmYHokHodOvtL0WCC 8A5PEP8tOk6029Z+J+xUcMrJClNVFpzVvOpb1lCbhjwAV465Hy+NUSbbUiRxdzNQtLtgZzOV Zw7jxUCs4UUZLQTCuBpFgb15bBxYZ/BL9MbzxPxvfUQIPbnzQMcqtpUs21CMK2PdfCh5c4gS sDci6D5/ZIBw94UQWmGpM/O1ilGXde2ZzzGYl64glmccD8e87OnEgKnH3FbnJnT4iJchtSvx yJNi1+t0+qDti4m88+/9IuPqCKb6Stl+s2dnLtJNrjXBGJtsQG/sRpqsJz5x1/2nPJSRMsx9 5YfqbdrJSOFXDzZ8/r82HgQEtUvlSXNaXCa95ez0UkOG7+bDm2b3s0XahBQeLVCH0mw3RAQg r7xDAYKIrAwfHHmMTnBQDPJwVqxJjVNr7yBic4yfzVWGCGNE4DnOW0vcIeoyhy9vnIa3w1uZ 3iyY2Nsd7JxfKu1PRhCGwXzRw5TlfEsoRI7V9A8isUCoqE2Dzh3FvYHVeX4Us+bRL/oqareJ CIFqgYMyvHj7Q06kTKmauOe4Nf0l0qEkIuIzfoLJ3qr5UyXc2hLtWyT9Ir+lYlX9efqh7mOY qIws/H2t In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/26/26 13:08, fujunjie wrote: > process_madvise() validates the advice while walking the imported iovec. > If the iovec has zero total length, vector_madvise() never enters the > loop and returns 0 without checking whether the advice value is valid. > > For a local mm, such as process_madvise(PIDFD_SELF, ...), the remote-only > process_madvise_remote_valid() check is skipped. As a result, an invalid > advice can be reported as success when the vector has zero total length. > This differs from madvise(), which rejects an invalid advice before > returning success for a zero-length range. > > Reject invalid advice before walking the vector. Valid zero-length > requests remain no-ops and continue to return 0. > > Add a selftest that covers invalid advice with a zero-length iovec and an > empty vector, while also checking that a valid zero-length request still > succeeds. > > Fixes: 021781b01275 ("mm/madvise: unrestrict process_madvise() for current process") > Signed-off-by: fujunjie > --- > Testing: > - Built bzImage. > - Built tools/testing/selftests/mm/process_madv. > - Ran tools/testing/selftests/mm/process_madv in QEMU: > # PASSED: 7 / 7 tests passed. > > mm/madvise.c | 3 +++ > tools/testing/selftests/mm/process_madv.c | 29 +++++++++++++++++++++++ > 2 files changed, 32 insertions(+) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 69708e953cf56..83fe9e651a907 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -2046,6 +2046,9 @@ static ssize_t vector_madvise(struct mm_struct *mm, struct iov_iter *iter, > > total_len = iov_iter_count(iter); > > + if (!madvise_behavior_valid(behavior)) > + return -EINVAL; > + I'd suggest performing the check just before the !process_madvise_remote_valid() check, such that "invalid/unsupported" orders are reported in the same priority, independent of local vs. non-local MM. Or is there a good reason to not do it there? -- Cheers, David