From patchwork Mon Sep 5 12:24:49 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12966072 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id D470CECAAD3 for ; Mon, 5 Sep 2022 12:26:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6F3608D0090; Mon, 5 Sep 2022 08:26:52 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6A30C8D0076; Mon, 5 Sep 2022 08:26:52 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5432E8D0090; Mon, 5 Sep 2022 08:26:52 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 41DF88D0076 for ; Mon, 5 Sep 2022 08:26:52 -0400 (EDT) Received: from smtpin11.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay05.hostedemail.com (Postfix) with ESMTP id 21735406D4 for ; Mon, 5 Sep 2022 12:26:52 +0000 (UTC) X-FDA: 79877955864.11.2E9B507 Received: from mail-ed1-f73.google.com (mail-ed1-f73.google.com [209.85.208.73]) by imf10.hostedemail.com (Postfix) with ESMTP id C0906C005D for ; Mon, 5 Sep 2022 12:26:51 +0000 (UTC) Received: by mail-ed1-f73.google.com with SMTP id z6-20020a05640240c600b0043e1d52fd98so5818949edb.22 for ; Mon, 05 Sep 2022 05:26:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date; bh=S+kwzH5LfDyg6tc+T47KWRR4zTWxpHjqyuN2TRvGEwc=; b=S7wqzmITpHaUQQ601PmLQLF2AnmzFvH8vp75pKlPuqlSL7XFiQiV+t+CuEVS9rDc95 YTC/2jROe8XrsYRkg6GR5NJZ4gxO13PXYLci1oXhoxmtUx0U3dXDpYhzBRe8xP1bBa1m yUX8soFx5DjE2Hzv1jICZdgm1K8X05X3C3aaKK6hLn3Rb9NHbi326B4nIbBWD+rOYDv/ 5ZdbvrOGFekGi9ZJSlEgsbw5zNeE90cnWYu9B0CzyO0fYDFO05KMXAU3Eu7pvo403nYZ 6hoSikjaW4BYgn6KVYp/rm30IbcA9hcfc75g6Q8jUpc+cz7+8xIzSrkwlFb9hqN+tsc8 2DZw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date; bh=S+kwzH5LfDyg6tc+T47KWRR4zTWxpHjqyuN2TRvGEwc=; b=JvbznwZS8VFRWU2fZQj3fZTKs5s366wJ23ISpYoGkQIDpD/bWjcOO3tQxI6YHeYmq8 IzcFC9BlNtOQJQmLZg6YAIeYZJi+/kXlde4h9JutVx6+Ixevpy3mOthxU9jEKYGqHPby j1eA/WNrik1YarPf8eVlJhm6ziEDsEfgvkwE1kNfgHriA+7IqFv0T/u6OOI6W7qT42G8 xqNIiKsTO2pAr640giC+gkKy212nKo7wB78sv3EmSyQGkMHI8IF6v84/Txlpru3Viv2u JVOJkVucsImhCIOkM/GVhCCMjyjDoW0luB9Lrf5O409Bx5GuBQDRt7hPghOJsTRpaZAN ST4g== X-Gm-Message-State: ACgBeo2+hz32ToXKb60EVruj9g9ccAOdwaaQifdxYyF3CQi+ZRCvZLdW XceRXf3BNyHg5s+B9amy2+KSBNTZE88= X-Google-Smtp-Source: AA6agR4mQQNFmEgVYN7X2/LANotTJ/QIMRRFfD7L/MO50ymq0vfCSKCuMncm7i/c02baCigU27aXPo0cYqA= X-Received: from glider.muc.corp.google.com ([2a00:79e0:9c:201:b808:8d07:ab4a:554c]) (user=glider job=sendgmr) by 2002:a50:ff13:0:b0:43e:76d3:63e1 with SMTP id a19-20020a50ff13000000b0043e76d363e1mr42442604edu.271.1662380810584; Mon, 05 Sep 2022 05:26:50 -0700 (PDT) Date: Mon, 5 Sep 2022 14:24:49 +0200 In-Reply-To: <20220905122452.2258262-1-glider@google.com> Mime-Version: 1.0 References: <20220905122452.2258262-1-glider@google.com> X-Mailer: git-send-email 2.37.2.789.g6183377224-goog Message-ID: <20220905122452.2258262-42-glider@google.com> Subject: [PATCH v6 41/44] entry: kmsan: introduce kmsan_unpoison_entry_regs() From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Alexei Starovoitov , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org ARC-Authentication-Results: i=1; imf10.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=S7wqzmIT; spf=pass (imf10.hostedemail.com: domain of 3CusVYwYKCFc5A723G5DD5A3.1DBA7CJM-BB9Kz19.DG5@flex--glider.bounces.google.com designates 209.85.208.73 as permitted sender) smtp.mailfrom=3CusVYwYKCFc5A723G5DD5A3.1DBA7CJM-BB9Kz19.DG5@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1662380811; a=rsa-sha256; cv=none; b=CSAchlNU6ZxTp3Nu/ixN66kHx5mWlVhDy/pIFUNZijjjKbaPdxsObqSoGXCj8GoG56O85v Hw0iigbKNwHBqx7qxl4yOVJ2ofXKShsOsAXrjf+Pn58BsAwhI2BY1KCsItuUHiLESAap1l F4wrvVa8T7K0INGsKCqO7Ll5i824GYM= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1662380811; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=S+kwzH5LfDyg6tc+T47KWRR4zTWxpHjqyuN2TRvGEwc=; b=pY3AearT/G84z4bX+cE3Rnhw2eNuZ3BmBIjCr0N1DBiGkXurVnbHr2sKu9c2ffa1lRa5VV DeivWtzzV9PSRngqhZj0d0JoMaRnenFU1XleQ+W6QOU1XMLaab12CR0+UiTJH3eghjkunh AJp15pIUJjF/fmRcrxh5rQeDrlYnjQk= X-Rspam-User: Authentication-Results: imf10.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=S7wqzmIT; spf=pass (imf10.hostedemail.com: domain of 3CusVYwYKCFc5A723G5DD5A3.1DBA7CJM-BB9Kz19.DG5@flex--glider.bounces.google.com designates 209.85.208.73 as permitted sender) smtp.mailfrom=3CusVYwYKCFc5A723G5DD5A3.1DBA7CJM-BB9Kz19.DG5@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: C0906C005D X-Stat-Signature: xxrsaj8gwp4pikjgbxwxdprobcnh8u6o X-HE-Tag: 1662380811-941810 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: struct pt_regs passed into IRQ entry code is set up by uninstrumented asm functions, therefore KMSAN may not notice the registers are initialized. kmsan_unpoison_entry_regs() unpoisons the contents of struct pt_regs, preventing potential false positives. Unlike kmsan_unpoison_memory(), it can be called under kmsan_in_runtime(), which is often the case in IRQ entry code. Signed-off-by: Alexander Potapenko --- Link: https://linux-review.googlesource.com/id/Ibfd7018ac847fd8e5491681f508ba5d14e4669cf --- include/linux/kmsan.h | 15 +++++++++++++++ kernel/entry/common.c | 5 +++++ mm/kmsan/hooks.c | 26 ++++++++++++++++++++++++++ 3 files changed, 46 insertions(+) diff --git a/include/linux/kmsan.h b/include/linux/kmsan.h index c473e0e21683c..e38ae3c346184 100644 --- a/include/linux/kmsan.h +++ b/include/linux/kmsan.h @@ -214,6 +214,17 @@ void kmsan_handle_dma_sg(struct scatterlist *sg, int nents, */ void kmsan_handle_urb(const struct urb *urb, bool is_out); +/** + * kmsan_unpoison_entry_regs() - Handle pt_regs in low-level entry code. + * @regs: struct pt_regs pointer received from assembly code. + * + * KMSAN unpoisons the contents of the passed pt_regs, preventing potential + * false positive reports. Unlike kmsan_unpoison_memory(), + * kmsan_unpoison_entry_regs() can be called from the regions where + * kmsan_in_runtime() returns true, which is the case in early entry code. + */ +void kmsan_unpoison_entry_regs(const struct pt_regs *regs); + #else static inline void kmsan_init_shadow(void) @@ -310,6 +321,10 @@ static inline void kmsan_handle_urb(const struct urb *urb, bool is_out) { } +static inline void kmsan_unpoison_entry_regs(const struct pt_regs *regs) +{ +} + #endif #endif /* _LINUX_KMSAN_H */ diff --git a/kernel/entry/common.c b/kernel/entry/common.c index 063068a9ea9b3..846add8394c41 100644 --- a/kernel/entry/common.c +++ b/kernel/entry/common.c @@ -5,6 +5,7 @@ #include #include #include +#include #include #include #include @@ -24,6 +25,7 @@ static __always_inline void __enter_from_user_mode(struct pt_regs *regs) user_exit_irqoff(); instrumentation_begin(); + kmsan_unpoison_entry_regs(regs); trace_hardirqs_off_finish(); instrumentation_end(); } @@ -352,6 +354,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) lockdep_hardirqs_off(CALLER_ADDR0); ct_irq_enter(); instrumentation_begin(); + kmsan_unpoison_entry_regs(regs); trace_hardirqs_off_finish(); instrumentation_end(); @@ -367,6 +370,7 @@ noinstr irqentry_state_t irqentry_enter(struct pt_regs *regs) */ lockdep_hardirqs_off(CALLER_ADDR0); instrumentation_begin(); + kmsan_unpoison_entry_regs(regs); rcu_irq_enter_check_tick(); trace_hardirqs_off_finish(); instrumentation_end(); @@ -452,6 +456,7 @@ irqentry_state_t noinstr irqentry_nmi_enter(struct pt_regs *regs) ct_nmi_enter(); instrumentation_begin(); + kmsan_unpoison_entry_regs(regs); trace_hardirqs_off_finish(); ftrace_nmi_enter(); instrumentation_end(); diff --git a/mm/kmsan/hooks.c b/mm/kmsan/hooks.c index 79d7e73e2cfd8..35f6b6e6a908c 100644 --- a/mm/kmsan/hooks.c +++ b/mm/kmsan/hooks.c @@ -348,6 +348,32 @@ void kmsan_unpoison_memory(const void *address, size_t size) } EXPORT_SYMBOL(kmsan_unpoison_memory); +/* + * Version of kmsan_unpoison_memory() that can be called from within the KMSAN + * runtime. + * + * Non-instrumented IRQ entry functions receive struct pt_regs from assembly + * code. Those regs need to be unpoisoned, otherwise using them will result in + * false positives. + * Using kmsan_unpoison_memory() is not an option in entry code, because the + * return value of in_task() is inconsistent - as a result, certain calls to + * kmsan_unpoison_memory() are ignored. kmsan_unpoison_entry_regs() ensures that + * the registers are unpoisoned even if kmsan_in_runtime() is true in the early + * entry code. + */ +void kmsan_unpoison_entry_regs(const struct pt_regs *regs) +{ + unsigned long ua_flags; + + if (!kmsan_enabled) + return; + + ua_flags = user_access_save(); + kmsan_internal_unpoison_memory((void *)regs, sizeof(*regs), + KMSAN_POISON_NOCHECK); + user_access_restore(ua_flags); +} + void kmsan_check_memory(const void *addr, size_t size) { if (!kmsan_enabled)