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 DB6F7388E6B; Wed, 13 May 2026 10:05:54 +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=1778666754; cv=none; b=RHqE/I3Jt+Tb9BZD9NbnoIKJoj/vj2lfZDwJKSReJUFZwFLkx54ZzMea+U254n0V8z3QzEPH58TwFVduhpQ8V05LWdAQSOBB0EZDt21H4NwfalhdZH3xIg4Mp4EN6oxeSbung9f+FOv5EmsAQRRgGzIY+m1/Ao7XoJVoAuW72yo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778666754; c=relaxed/simple; bh=xmU4wBziLf70Ok0B+UMn+MM2UYmio1xuQY4yM+as3/g=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=bhwKwzQIMPAcwDgUL1Pxk/drS48+Djqq09lgRUT2OpGI6fVWmnBwU9gM5loFNIp26ETpKmKOsCUhRd0S7wmOPkdq+iMKCZcbT/j/GSaj3jcpp4e0FZVQK+Lf5lYoYFY+lCrS/thIYSXU5HaiYIPLd4KVbdOLQg4KM6qlQMszupc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=egQzb8mj; 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="egQzb8mj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B37EEC2BCB7; Wed, 13 May 2026 10:05:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1778666754; bh=xmU4wBziLf70Ok0B+UMn+MM2UYmio1xuQY4yM+as3/g=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=egQzb8mjFyNnn+lIWZTsTJk4rD/PWO+MJWaS96RqxXXY3WhdlXpL5XJE8DyXkm75C 6SGAhgCDmZxl6qVmCpsXrYnYY/z7JQ2CHa2ytHUJ4jP3/xmPY6ntSuAsKfi/EhoNvx /JavDPD/oBAoCq+smnpFtH/vMULVmp4kERvnftM8RI4aX/EE8fu8hs2nVp1Szg9H3T jcTAbdhviP+Qp6Okve8J1TZgEcWLI0rncY/SrPdmFroq/anunCsQAm2bGvlDCfNied yUTGqSW3LHRtF6/LvgPt1kv1hnFRxf8w95DxLZeOgblLj8oJwdkmGNuWlsl25too9a Do2yrfe7UpXoQ== Message-ID: <9e302879-d218-4257-9e2b-e468564b89ea@kernel.org> Date: Wed, 13 May 2026 12:05:49 +0200 Precedence: bulk X-Mailing-List: linux-kselftest@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] selftests/mm: Fix incorrect mmap() error handling with NULL instead of MAP_FAILED To: Hongfu Li , akpm@linux-foundation.org, ljs@kernel.org, liam@infradead.org, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, shuah@kernel.org Cc: linux-mm@kvack.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Dev Jain References: <20260513095609.789935-1-lihongfu@kylinos.cn> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 5/13/26 11:56, Hongfu Li wrote: > mmap() returns MAP_FAILED, which is defined as (void *)-1, on error, > not NULL. Several selftests incorrectly check the return value of > mmap() using !ptr or ptr == NULL, which would erroneously treat > MAP_FAILED as a valid pointer since MAP_FAILED is non-zero and > non-NULL. This can lead to segfaults when mmap() actually fails > under memory pressure. Well, your patch also adds more checks where we previously didn't have any checks? > > Signed-off-by: Hongfu Li > Reviewed-by: Dev Jain > --- > v2: > - Add missing mmap() return value checks in pkey_sighandler_tests.c > and protection_keys.c > --- [...] > diff --git a/tools/testing/selftests/mm/protection_keys.c b/tools/testing/selftests/mm/protection_keys.c > index 2085982dba69..580bf1668c71 100644 > --- a/tools/testing/selftests/mm/protection_keys.c > +++ b/tools/testing/selftests/mm/protection_keys.c > @@ -1217,6 +1217,7 @@ static void arch_force_pkey_reg_init(void) > * doing the XSAVE size enumeration dance. > */ > buf = mmap(NULL, 1*MB, PROT_READ|PROT_WRITE, MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); > + pkey_assert(buf != (void *)-1); What's the reason for not using MAP_FAILED? -- Cheers, David