From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AIpwx49cLpJbfjYhT2xyZfYfdGqVbtb7xeuKd30mqgyIVUSewGyZuf4/CgMSKpSutFEf94ADyc8G ARC-Seal: i=1; a=rsa-sha256; t=1523021512; cv=none; d=google.com; s=arc-20160816; b=varqeBAhn7CMEJ1k2v8qJ8X29RzTTWVm8oKs8fbobSWQeQZTMgRAxbDz+J5ZyzvXpd CSqBYX7QVm6SSm23YYM84Q+BpyrI+lo3uJJS9guXzdPixEAVIQ3AcUSCfBTO4QQB8txt fRJdLCyJdZ6BD+fyF7rsHe5DF4Q0hIVbVjoYCKAWnGjxabXBKE4Zh9Fg9EHV1gpLbQmk ed7lcc1IoHmyW5R+zDIs4ZrDRDP1GkTkSiK/i3Zyo7+IM6BgR68RjkpXN8IRhpoBR9SQ OFg0JMe4K9f11SvT0ACIneOCoLWtlkA7acuohYyc5heXFnGRj5AQKnUwXmuM3iuq1Cq5 SBfw== 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=KMFtC7DviRHpNFiDEPT72XprLhhRnBvIYiJQebEugy8=; b=KxRX4bM/jsM+bLYPjl3aOfuRBa+S5Vq/8vqYXZqciJ2bBW8Ox13PWgqKxRfCGTDHcl kNOnvp8/SyV+Sv4GLnpaMbM6y8vZSjto6IJ8h/iSaoXc76I1vvwqrYjQQEMUn+xF1YPs CufgaUHoRM9lyMtTVXgKrApRstxrOtK7pqN0xPHh6VwoOlT37JIiO2fk7kT087jj3oi1 jPrQaxTNSZhoCoB72ZgKyWn+NJnCL7IV4pusHe7cPEtgt050CgpCN7IPZv8xPDqTn1BS HUiUBXCoPp7HaqVEF5EGCimKG2ksTSYbrrk2XyohU9z9RAWvbhbGfoVd+7daLUJlbSlt mi/w== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.61.202 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 90.92.61.202 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 , Ben Hutchings Subject: [PATCH 4.4 64/72] nospec: Kill array_index_nospec_mask_check() Date: Fri, 6 Apr 2018 15:24:05 +0200 Message-Id: <20180406084310.804074694@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180406084305.210085169@linuxfoundation.org> References: <20180406084305.210085169@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?1597003805670410036?= X-GMAIL-MSGID: =?utf-8?q?1597003805670410036?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.4-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 Cc: Ben Hutchings 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 @@ -31,26 +31,6 @@ 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: @@ -68,7 +48,7 @@ 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)); \