From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELtawlxTxIV3F4vTtuVygNkhiwx1vzcO6EriPH9rxhB6T8b08Kua2/SVUSPVwDjah/+ZBz/2 ARC-Seal: i=1; a=rsa-sha256; t=1520955628; cv=none; d=google.com; s=arc-20160816; b=sFb9d7QCuP+mHPsirQ4ONn7j5MiLG5DoT+amnuEhir2ZpPM39Q5wFY9B5E8YgI67WP 9VCfnQKy35fEzgzMrHKVO9GvuFT7X6VRAi5buZ0Hs5G9Ahtf0a7ttRNCaBgnPHMbDhQJ 9nVVi/tPjKVzeDdZE10cUoBM5veCc71Z2V+stB/STZdaL7qORICs987HO/mvAUTQnRQr 19e5GILuHnkLyXflzDBwsJtak3OjuzHUnVD5tc1n33qMZpKrEGrwBWdecfbVQR2Mapcm +r3OQ6kbNfoqPBbWw554MGLUgGjis0cxCVbaCrSDDsITWrIDkfikhqmDg+HLtwm/VO0f 3FQw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=/dkbh1bv3GXXD+gN/EOuu2Xp2l1ooGHgDxV6wGqX40A=; b=annv3nABJ9oLlNEiH3+EuCFH4Z2Fva6chY2Bt0KNXdwCrwrkarXx9az4QttrvtNP2w +29aWSSruCQTms59AJDvAV8co5GccSMauUruDjTVXgBs9ycus8N4RgN3VoictdhjmKQQ MavkavwvKN+wKSnKXP9ExTNcZMHECItfnIIQGgNC+akZib84HWE9BxEnwLNooywu2tRH us+wWT9rWg5Mlkw4BLnkfABGhiyHC2uaue+RRaX1lv2fMpzLWtLf8EZZt8ywVZ6STuwe Agoh4/0er/JWENzijd3yz0HJRDTKYBXmR9w0bLuCx/UvshTjFTbhyHewiyRuVztFp8Y1 5viw== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Linus Torvalds , Dan Williams , Andy Lutomirski , Arjan van de Ven , Borislav Petkov , Dave Hansen , David Woodhouse , Josh Poimboeuf , Peter Zijlstra , Thomas Gleixner , Will Deacon , linux-arch@vger.kernel.org, Ingo Molnar Subject: [PATCH 4.14 115/140] nospec: Kill array_index_nospec_mask_check() Date: Tue, 13 Mar 2018 16:25:18 +0100 Message-Id: <20180313152505.911920624@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180313152458.201155692@linuxfoundation.org> References: <20180313152458.201155692@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1594836987780725095?= X-GMAIL-MSGID: =?utf-8?q?1594837569126961886?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit 1d91c1d2c80cb70e2e553845e278b87a960c04da upstream. There are multiple problems with the dynamic sanity checking in array_index_nospec_mask_check(): * It causes unnecessary overhead in the 32-bit case since integer sized @index values will no longer cause the check to be compiled away like in the 64-bit case. * In the 32-bit case it may trigger with user controllable input when the expectation is that should only trigger during development of new kernel enabling. * The macro reuses the input parameter in multiple locations which is broken if someone passes an expression like 'index++' to array_index_nospec(). Reported-by: Linus Torvalds Signed-off-by: Dan Williams Cc: Andy Lutomirski Cc: Arjan van de Ven Cc: Borislav Petkov Cc: Dave Hansen Cc: David Woodhouse Cc: Greg Kroah-Hartman Cc: Josh Poimboeuf Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Will Deacon Cc: linux-arch@vger.kernel.org Link: http://lkml.kernel.org/r/151881604278.17395.6605847763178076520.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- include/linux/nospec.h | 22 +--------------------- 1 file changed, 1 insertion(+), 21 deletions(-) --- a/include/linux/nospec.h +++ b/include/linux/nospec.h @@ -30,26 +30,6 @@ static inline unsigned long array_index_ #endif /* - * Warn developers about inappropriate array_index_nospec() usage. - * - * Even if the CPU speculates past the WARN_ONCE branch, the - * sign bit of @index is taken into account when generating the - * mask. - * - * This warning is compiled out when the compiler can infer that - * @index and @size are less than LONG_MAX. - */ -#define array_index_mask_nospec_check(index, size) \ -({ \ - if (WARN_ONCE(index > LONG_MAX || size > LONG_MAX, \ - "array_index_nospec() limited to range of [0, LONG_MAX]\n")) \ - _mask = 0; \ - else \ - _mask = array_index_mask_nospec(index, size); \ - _mask; \ -}) - -/* * array_index_nospec - sanitize an array index after a bounds check * * For a code sequence like: @@ -67,7 +47,7 @@ static inline unsigned long array_index_ ({ \ typeof(index) _i = (index); \ typeof(size) _s = (size); \ - unsigned long _mask = array_index_mask_nospec_check(_i, _s); \ + unsigned long _mask = array_index_mask_nospec(_i, _s); \ \ BUILD_BUG_ON(sizeof(_i) > sizeof(long)); \ BUILD_BUG_ON(sizeof(_s) > sizeof(long)); \