From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752052AbdF3MtK (ORCPT ); Fri, 30 Jun 2017 08:49:10 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:47921 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751545AbdF3MtI (ORCPT ); Fri, 30 Jun 2017 08:49:08 -0400 From: "Eric W. Biederman" To: linux-kernel@vger.kernel.org Cc: Andy Lutomirski , Linus Torvalds , Al Viro , Oleg Nesterov , Andrei Vagin , Thomas Gleixner , Greg KH , Andrey Vagin , Serge Hallyn , Pavel Emelyanov , Cyrill Gorcunov , Peter Zijlstra , Willy Tarreau , linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Linux Containers , Michael Kerrisk , "Eric W. Biederman" , "David S. Miller" , sparclinux@vger.kernel.org Date: Fri, 30 Jun 2017 07:39:01 -0500 Message-Id: <20170630123906.8865-3-ebiederm@xmission.com> X-Mailer: git-send-email 2.10.1 In-Reply-To: <87efu22set.fsf@xmission.com> References: <87efu22set.fsf@xmission.com> X-XM-SPF: eid=1dQvKF-00026H-9r;;;mid=<20170630123906.8865-3-ebiederm@xmission.com>;;;hst=in01.mta.xmission.com;;;ip=67.3.213.87;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19mKVOUoChWNLbuTRAxowZqSv995nVu/+4= X-SA-Exim-Connect-IP: 67.3.213.87 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 TVD_RCVD_IP Message was received from an IP address * 1.5 XMNoVowels Alpha-numberic number with no vowels * 0.7 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * 0.1 URIBL_SBL_A Contains URL's A record listed in the SBL blocklist * [URIs: davemloft.net] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa07 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa07 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: **;linux-kernel@vger.kernel.org X-Spam-Relay-Country: X-Spam-Timing: total 5681 ms - load_scoreonly_sql: 0.06 (0.0%), signal_user_changed: 2.4 (0.0%), b_tie_ro: 1.56 (0.0%), parse: 0.93 (0.0%), extract_message_metadata: 15 (0.3%), get_uri_detail_list: 1.75 (0.0%), tests_pri_-1000: 8 (0.1%), tests_pri_-950: 1.26 (0.0%), tests_pri_-900: 1.06 (0.0%), tests_pri_-400: 30 (0.5%), check_bayes: 29 (0.5%), b_tokenize: 9 (0.2%), b_tok_get_all: 11 (0.2%), b_comp_prob: 2.1 (0.0%), b_tok_touch_all: 4.7 (0.1%), b_finish: 0.59 (0.0%), tests_pri_0: 288 (5.1%), check_dkim_signature: 0.89 (0.0%), check_dkim_adsp: 3.5 (0.1%), tests_pri_500: 5331 (93.8%), poll_dns_idle: 5326 (93.7%), rewrite_mail: 0.00 (0.0%) Subject: [PATCH 3/8] signal/sparc: Document a conflict with SI_USER with SIGFPE X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Setting si_code to __SI_FAULT results in a userspace seeing an si_code of 0. This is the same si_code as SI_USER. Posix and common sense requires that SI_USER not be a signal specific si_code. As such this use of 0 for the si_code is a pretty horribly broken ABI. This was introduced in 2.3.41 so this mess has had a long time for people to be able to start depending on it. As this bug has existed for 17 years already I don't know if it is worth fixing. It is definitely worth documenting what is going on so that no one decides to copy this bad decision. Cc: "David S. Miller" Cc: sparclinux@vger.kernel.org Signed-off-by: "Eric W. Biederman" --- arch/sparc/include/uapi/asm/siginfo.h | 5 +++++ arch/sparc/kernel/traps_32.c | 2 +- arch/sparc/kernel/traps_64.c | 2 +- 3 files changed, 7 insertions(+), 2 deletions(-) diff --git a/arch/sparc/include/uapi/asm/siginfo.h b/arch/sparc/include/uapi/asm/siginfo.h index 2d9b79ccaa50..6bc5c677e92f 100644 --- a/arch/sparc/include/uapi/asm/siginfo.h +++ b/arch/sparc/include/uapi/asm/siginfo.h @@ -17,6 +17,11 @@ #define SI_NOINFO 32767 /* no information in siginfo_t */ /* + * SIGFPE si_codes + */ +#define FPE_FIXME (__SI_FAULT|0) /* Broken dup of SI_USER */ + +/* * SIGEMT si_codes */ #define EMT_TAGOVF (__SI_FAULT|1) /* tag overflow */ diff --git a/arch/sparc/kernel/traps_32.c b/arch/sparc/kernel/traps_32.c index 466d4aed06c7..581cf35ee7e3 100644 --- a/arch/sparc/kernel/traps_32.c +++ b/arch/sparc/kernel/traps_32.c @@ -306,7 +306,7 @@ void do_fpe_trap(struct pt_regs *regs, unsigned long pc, unsigned long npc, info.si_errno = 0; info.si_addr = (void __user *)pc; info.si_trapno = 0; - info.si_code = __SI_FAULT; + info.si_code = FPE_FIXME; if ((fsr & 0x1c000) == (1 << 14)) { if (fsr & 0x10) info.si_code = FPE_FLTINV; diff --git a/arch/sparc/kernel/traps_64.c b/arch/sparc/kernel/traps_64.c index 196ee5eb4d48..e882e128faa3 100644 --- a/arch/sparc/kernel/traps_64.c +++ b/arch/sparc/kernel/traps_64.c @@ -2258,7 +2258,7 @@ static void do_fpe_common(struct pt_regs *regs) info.si_errno = 0; info.si_addr = (void __user *)regs->tpc; info.si_trapno = 0; - info.si_code = __SI_FAULT; + info.si_code = FPE_FIXME; if ((fsr & 0x1c000) == (1 << 14)) { if (fsr & 0x10) info.si_code = FPE_FLTINV; -- 2.10.1