From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755021AbcKNRzs (ORCPT ); Mon, 14 Nov 2016 12:55:48 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:44416 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754030AbcKNRzm (ORCPT ); Mon, 14 Nov 2016 12:55:42 -0500 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, Kees Cook , "Paul E. McKenney" Subject: [PATCH tip/core/rcu 4/7] bug: Provide toggle for BUG on data corruption Date: Mon, 14 Nov 2016 09:55:30 -0800 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20161114175500.GA21637@linux.vnet.ibm.com> References: <20161114175500.GA21637@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16111417-0016-0000-0000-0000052B7674 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006077; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000189; SDB=6.00780621; UDB=6.00376448; IPR=6.00558123; BA=6.00004878; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013322; XFM=3.00000011; UTC=2016-11-14 17:55:40 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16111417-0017-0000-0000-000034A2D74F Message-Id: <1479146133-23058-4-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-14_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1611140360 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kees Cook The kernel checks for cases of data structure corruption under some CONFIGs (e.g. CONFIG_DEBUG_LIST). When corruption is detected, some systems may want to BUG() immediately instead of letting the system run with known corruption. Usually these kinds of manipulation primitives can be used by security flaws to gain arbitrary memory write control. This provides a new config CONFIG_BUG_ON_DATA_CORRUPTION and a corresponding macro CHECK_DATA_CORRUPTION for handling these situations. Notably, even if not BUGing, the kernel should not continue processing the corrupted structure. This is inspired by similar hardening by Syed Rameez Mustafa in MSM kernels, and in PaX and Grsecurity, which is likely in response to earlier removal of the BUG calls in commit 924d9addb9b1 ("list debugging: use WARN() instead of BUG()"). Signed-off-by: Kees Cook Acked-by: Steven Rostedt Signed-off-by: Paul E. McKenney Acked-by: Rik van Riel --- include/linux/bug.h | 17 ++++++++++++++++ lib/Kconfig.debug | 10 ++++++++++ lib/list_debug.c | 57 +++++++++++++++++++++-------------------------------- 3 files changed, 49 insertions(+), 35 deletions(-) diff --git a/include/linux/bug.h b/include/linux/bug.h index 292d6a10b0c2..baff2e8fc8a8 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -121,4 +121,21 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr, } #endif /* CONFIG_GENERIC_BUG */ + +/* + * Since detected data corruption should stop operation on the affected + * structures, this returns false if the corruption condition is found. + */ +#define CHECK_DATA_CORRUPTION(condition, fmt, ...) \ + do { \ + if (unlikely(condition)) { \ + if (IS_ENABLED(CONFIG_BUG_ON_DATA_CORRUPTION)) { \ + pr_err(fmt, ##__VA_ARGS__); \ + BUG(); \ + } else \ + WARN(1, fmt, ##__VA_ARGS__); \ + return false; \ + } \ + } while (0) + #endif /* _LINUX_BUG_H */ diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 33bc56cf60d7..07a6fac930c5 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1960,6 +1960,16 @@ config TEST_STATIC_KEYS If unsure, say N. +config BUG_ON_DATA_CORRUPTION + bool "Trigger a BUG when data corruption is detected" + select CONFIG_DEBUG_LIST + help + Select this option if the kernel should BUG when it encounters + data corruption in kernel memory structures when they get checked + for validity. + + If unsure, say N. + source "samples/Kconfig" source "lib/Kconfig.kgdb" diff --git a/lib/list_debug.c b/lib/list_debug.c index 276565fca2a6..7f7bfa55eb6d 100644 --- a/lib/list_debug.c +++ b/lib/list_debug.c @@ -20,21 +20,16 @@ bool __list_add_valid(struct list_head *new, struct list_head *prev, struct list_head *next) { - if (unlikely(next->prev != prev)) { - WARN(1, "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n", - prev, next->prev, next); - return false; - } - if (unlikely(prev->next != next)) { - WARN(1, "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n", - next, prev->next, prev); - return false; - } - if (unlikely(new == prev || new == next)) { - WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n", - new, prev, next); - return false; - } + CHECK_DATA_CORRUPTION(next->prev != prev, + "list_add corruption. next->prev should be prev (%p), but was %p. (next=%p).\n", + prev, next->prev, next); + CHECK_DATA_CORRUPTION(prev->next != next, + "list_add corruption. prev->next should be next (%p), but was %p. (prev=%p).\n", + next, prev->next, prev); + CHECK_DATA_CORRUPTION(new == prev || new == next, + "list_add double add: new=%p, prev=%p, next=%p.\n", + new, prev, next); + return true; } EXPORT_SYMBOL(__list_add_valid); @@ -46,26 +41,18 @@ bool __list_del_entry_valid(struct list_head *entry) prev = entry->prev; next = entry->next; - if (unlikely(next == LIST_POISON1)) { - WARN(1, "list_del corruption, %p->next is LIST_POISON1 (%p)\n", - entry, LIST_POISON1); - return false; - } - if (unlikely(prev == LIST_POISON2)) { - WARN(1, "list_del corruption, %p->prev is LIST_POISON2 (%p)\n", - entry, LIST_POISON2); - return false; - } - if (unlikely(prev->next != entry)) { - WARN(1, "list_del corruption. prev->next should be %p, but was %p\n", - entry, prev->next); - return false; - } - if (unlikely(next->prev != entry)) { - WARN(1, "list_del corruption. next->prev should be %p, but was %p\n", - entry, next->prev); - return false; - } + CHECK_DATA_CORRUPTION(next == LIST_POISON1, + "list_del corruption, %p->next is LIST_POISON1 (%p)\n", + entry, LIST_POISON1); + CHECK_DATA_CORRUPTION(prev == LIST_POISON2, + "list_del corruption, %p->prev is LIST_POISON2 (%p)\n", + entry, LIST_POISON2); + CHECK_DATA_CORRUPTION(prev->next != entry, + "list_del corruption. prev->next should be %p, but was %p\n", + entry, prev->next); + CHECK_DATA_CORRUPTION(next->prev != entry, + "list_del corruption. next->prev should be %p, but was %p\n", + entry, next->prev); return true; } -- 2.5.2