From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D2C03C282DA for ; Wed, 17 Apr 2019 11:54:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9575920835 for ; Wed, 17 Apr 2019 11:54:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732101AbfDQLyV (ORCPT ); Wed, 17 Apr 2019 07:54:21 -0400 Received: from mx2.suse.de ([195.135.220.15]:43696 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732075AbfDQLyS (ORCPT ); Wed, 17 Apr 2019 07:54:18 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0B627AFBF; Wed, 17 Apr 2019 11:54:16 +0000 (UTC) From: Petr Mladek To: Andy Shevchenko , Rasmus Villemoes Cc: Linus Torvalds , "Tobin C . Harding" , Joe Perches , Andrew Morton , Michal Hocko , Sergey Senozhatsky , Steven Rostedt , Sergey Senozhatsky , linux-kernel@vger.kernel.org, Petr Mladek Subject: [PATCH v7 03/10] vsprintf: Do not check address of well-known strings Date: Wed, 17 Apr 2019 13:53:43 +0200 Message-Id: <20190417115350.20479-4-pmladek@suse.com> X-Mailer: git-send-email 2.16.4 In-Reply-To: <20190417115350.20479-1-pmladek@suse.com> References: <20190417115350.20479-1-pmladek@suse.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org We are going to check the address using probe_kernel_address(). It will be more expensive and it does not make sense for well known address. This patch splits the string() function. The variant without the check is then used on locations that handle string constants or strings defined as local variables. This patch does not change the existing behavior. Signed-off-by: Petr Mladek Reviewed-by: Andy Shevchenko --- lib/vsprintf.c | 81 +++++++++++++++++++++++++++++++--------------------------- 1 file changed, 44 insertions(+), 37 deletions(-) diff --git a/lib/vsprintf.c b/lib/vsprintf.c index 2af48948a973..c9c9a1179870 100644 --- a/lib/vsprintf.c +++ b/lib/vsprintf.c @@ -593,15 +593,13 @@ char *widen_string(char *buf, int n, char *end, struct printf_spec spec) return buf; } -static noinline_for_stack -char *string(char *buf, char *end, const char *s, struct printf_spec spec) +/* Handle string from a well known address. */ +static char *string_nocheck(char *buf, char *end, const char *s, + struct printf_spec spec) { int len = 0; size_t lim = spec.precision; - if ((unsigned long)s < PAGE_SIZE) - s = "(null)"; - while (lim--) { char c = *s++; if (!c) @@ -615,6 +613,15 @@ char *string(char *buf, char *end, const char *s, struct printf_spec spec) } static noinline_for_stack +char *string(char *buf, char *end, const char *s, + struct printf_spec spec) +{ + if ((unsigned long)s < PAGE_SIZE) + s = "(null)"; + + return string_nocheck(buf, end, s, spec); +} + char *pointer_string(char *buf, char *end, const void *ptr, struct printf_spec spec) { @@ -701,7 +708,7 @@ static char *ptr_to_id(char *buf, char *end, const void *ptr, if (static_branch_unlikely(¬_filled_random_ptr_key)) { spec.field_width = 2 * sizeof(ptr); /* string length must be less than default_width */ - return string(buf, end, str, spec); + return string_nocheck(buf, end, str, spec); } #ifdef CONFIG_64BIT @@ -737,7 +744,7 @@ char *restricted_pointer(char *buf, char *end, const void *ptr, if (in_irq() || in_serving_softirq() || in_nmi()) { if (spec.field_width == -1) spec.field_width = 2 * sizeof(ptr); - return string(buf, end, "pK-error", spec); + return string_nocheck(buf, end, "pK-error", spec); } /* @@ -851,7 +858,7 @@ char *symbol_string(char *buf, char *end, void *ptr, else sprint_symbol_no_offset(sym, value); - return string(buf, end, sym, spec); + return string_nocheck(buf, end, sym, spec); #else return special_hex_number(buf, end, value, sizeof(void *)); #endif @@ -937,27 +944,27 @@ char *resource_string(char *buf, char *end, struct resource *res, *p++ = '['; if (res->flags & IORESOURCE_IO) { - p = string(p, pend, "io ", str_spec); + p = string_nocheck(p, pend, "io ", str_spec); specp = &io_spec; } else if (res->flags & IORESOURCE_MEM) { - p = string(p, pend, "mem ", str_spec); + p = string_nocheck(p, pend, "mem ", str_spec); specp = &mem_spec; } else if (res->flags & IORESOURCE_IRQ) { - p = string(p, pend, "irq ", str_spec); + p = string_nocheck(p, pend, "irq ", str_spec); specp = &default_dec_spec; } else if (res->flags & IORESOURCE_DMA) { - p = string(p, pend, "dma ", str_spec); + p = string_nocheck(p, pend, "dma ", str_spec); specp = &default_dec_spec; } else if (res->flags & IORESOURCE_BUS) { - p = string(p, pend, "bus ", str_spec); + p = string_nocheck(p, pend, "bus ", str_spec); specp = &bus_spec; } else { - p = string(p, pend, "??? ", str_spec); + p = string_nocheck(p, pend, "??? ", str_spec); specp = &mem_spec; decode = 0; } if (decode && res->flags & IORESOURCE_UNSET) { - p = string(p, pend, "size ", str_spec); + p = string_nocheck(p, pend, "size ", str_spec); p = number(p, pend, resource_size(res), *specp); } else { p = number(p, pend, res->start, *specp); @@ -968,21 +975,21 @@ char *resource_string(char *buf, char *end, struct resource *res, } if (decode) { if (res->flags & IORESOURCE_MEM_64) - p = string(p, pend, " 64bit", str_spec); + p = string_nocheck(p, pend, " 64bit", str_spec); if (res->flags & IORESOURCE_PREFETCH) - p = string(p, pend, " pref", str_spec); + p = string_nocheck(p, pend, " pref", str_spec); if (res->flags & IORESOURCE_WINDOW) - p = string(p, pend, " window", str_spec); + p = string_nocheck(p, pend, " window", str_spec); if (res->flags & IORESOURCE_DISABLED) - p = string(p, pend, " disabled", str_spec); + p = string_nocheck(p, pend, " disabled", str_spec); } else { - p = string(p, pend, " flags ", str_spec); + p = string_nocheck(p, pend, " flags ", str_spec); p = number(p, pend, res->flags, default_flag_spec); } *p++ = ']'; *p = '\0'; - return string(buf, end, sym, spec); + return string_nocheck(buf, end, sym, spec); } static noinline_for_stack @@ -1150,7 +1157,7 @@ char *mac_address_string(char *buf, char *end, u8 *addr, } *p = '\0'; - return string(buf, end, mac_addr, spec); + return string_nocheck(buf, end, mac_addr, spec); } static noinline_for_stack @@ -1313,7 +1320,7 @@ char *ip6_addr_string(char *buf, char *end, const u8 *addr, else ip6_string(ip6_addr, addr, fmt); - return string(buf, end, ip6_addr, spec); + return string_nocheck(buf, end, ip6_addr, spec); } static noinline_for_stack @@ -1324,7 +1331,7 @@ char *ip4_addr_string(char *buf, char *end, const u8 *addr, ip4_string(ip4_addr, addr, fmt); - return string(buf, end, ip4_addr, spec); + return string_nocheck(buf, end, ip4_addr, spec); } static noinline_for_stack @@ -1386,7 +1393,7 @@ char *ip6_addr_string_sa(char *buf, char *end, const struct sockaddr_in6 *sa, } *p = '\0'; - return string(buf, end, ip6_addr, spec); + return string_nocheck(buf, end, ip6_addr, spec); } static noinline_for_stack @@ -1421,7 +1428,7 @@ char *ip4_addr_string_sa(char *buf, char *end, const struct sockaddr_in *sa, } *p = '\0'; - return string(buf, end, ip4_addr, spec); + return string_nocheck(buf, end, ip4_addr, spec); } static noinline_for_stack @@ -1522,7 +1529,7 @@ char *uuid_string(char *buf, char *end, const u8 *addr, *p = 0; - return string(buf, end, uuid, spec); + return string_nocheck(buf, end, uuid, spec); } static noinline_for_stack @@ -1736,13 +1743,13 @@ char *device_node_gen_full_name(const struct device_node *np, char *buf, char *e /* special case for root node */ if (!parent) - return string(buf, end, "/", default_str_spec); + return string_nocheck(buf, end, "/", default_str_spec); for (depth = 0; parent->parent; depth++) parent = parent->parent; for ( ; depth >= 0; depth--) { - buf = string(buf, end, "/", default_str_spec); + buf = string_nocheck(buf, end, "/", default_str_spec); buf = string(buf, end, device_node_name_for_depth(np, depth), default_str_spec); } @@ -1770,10 +1777,10 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, str_spec.field_width = -1; if (!IS_ENABLED(CONFIG_OF)) - return string(buf, end, "(!OF)", spec); + return string_nocheck(buf, end, "(!OF)", spec); if ((unsigned long)dn < PAGE_SIZE) - return string(buf, end, "(null)", spec); + return string_nocheck(buf, end, "(null)", spec); /* simple case without anything any more format specifiers */ fmt++; @@ -1814,7 +1821,7 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, tbuf[2] = of_node_check_flag(dn, OF_POPULATED) ? 'P' : '-'; tbuf[3] = of_node_check_flag(dn, OF_POPULATED_BUS) ? 'B' : '-'; tbuf[4] = 0; - buf = string(buf, end, tbuf, str_spec); + buf = string_nocheck(buf, end, tbuf, str_spec); break; case 'c': /* major compatible string */ ret = of_property_read_string(dn, "compatible", &p); @@ -1825,10 +1832,10 @@ char *device_node_string(char *buf, char *end, struct device_node *dn, has_mult = false; of_property_for_each_string(dn, "compatible", prop, p) { if (has_mult) - buf = string(buf, end, ",", str_spec); - buf = string(buf, end, "\"", str_spec); + buf = string_nocheck(buf, end, ",", str_spec); + buf = string_nocheck(buf, end, "\"", str_spec); buf = string(buf, end, p, str_spec); - buf = string(buf, end, "\"", str_spec); + buf = string_nocheck(buf, end, "\"", str_spec); has_mult = true; } @@ -1966,7 +1973,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, */ if (spec.field_width == -1) spec.field_width = default_width; - return string(buf, end, "(null)", spec); + return string_nocheck(buf, end, "(null)", spec); } switch (*fmt) { @@ -2022,7 +2029,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr, case AF_INET6: return ip6_addr_string_sa(buf, end, &sa->v6, spec, fmt); default: - return string(buf, end, "(invalid address)", spec); + return string_nocheck(buf, end, "(invalid address)", spec); }} } break; -- 2.16.4