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authorLinus Torvalds <torvalds@linux-foundation.org>2016-12-12 09:09:54 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2016-12-12 09:09:54 -0800
commit718c0ddd6aa911fd2a6fb1b6e050fbaee8060e61 (patch)
tree8f502a67605f864773d96dca7c8c6e1a9fa3f322 /lib
parent8fa3b6f9392bf6d90cb7b908e07bd90166639f0a (diff)
parentaf91a81131aee3e233a977632a23b839857a327b (diff)
downloadlinux-stericsson-718c0ddd6aa911fd2a6fb1b6e050fbaee8060e61.tar.gz
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU updates from Ingo Molnar: "The main RCU changes in this development cycle were: - Miscellaneous fixes, including a change to call_rcu()'s rcu_head alignment check. - Security-motivated list consistency checks, which are disabled by default behind DEBUG_LIST. - Torture-test updates. - Documentation updates, yet again just simple changes" * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: torture: Prevent jitter from delaying build-only runs torture: Remove obsolete files from rcutorture .gitignore rcu: Don't kick unless grace period or request rcu: Make expedited grace periods recheck dyntick idle state torture: Trace long read-side delays rcu: RCU_TRACE enables event tracing as well as debugfs rcu: Remove obsolete comment from __call_rcu() rcu: Remove obsolete rcu_check_callbacks() header comment rcu: Tighten up __call_rcu() rcu_head alignment check Documentation/RCU: Fix minor typo documentation: Present updated RCU guarantee bug: Avoid Kconfig warning for BUG_ON_DATA_CORRUPTION lib/Kconfig.debug: Fix typo in select statement lkdtm: Add tests for struct list corruption bug: Provide toggle for BUG on data corruption list: Split list_del() debug checking into separate function rculist: Consolidate DEBUG_LIST for list_add_rcu() list: Split list_add() debug checking into separate function
Diffstat (limited to 'lib')
-rw-r--r--lib/Kconfig.debug15
-rw-r--r--lib/list_debug.c99
2 files changed, 42 insertions, 72 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index a6c8db1d62f6..9bb7d825ba14 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1218,7 +1218,7 @@ config DEBUG_BUGVERBOSE
config DEBUG_LIST
bool "Debug linked list manipulation"
- depends on DEBUG_KERNEL
+ depends on DEBUG_KERNEL || BUG_ON_DATA_CORRUPTION
help
Enable this to turn on extended checks in the linked-list
walking routines.
@@ -1434,7 +1434,8 @@ config RCU_TRACE
select TRACE_CLOCK
help
This option provides tracing in RCU which presents stats
- in debugfs for debugging RCU implementation.
+ in debugfs for debugging RCU implementation. It also enables
+ additional tracepoints for ftrace-style event tracing.
Say Y here if you want to enable RCU tracing
Say N if you are unsure.
@@ -1964,6 +1965,16 @@ config TEST_STATIC_KEYS
If unsure, say N.
+config BUG_ON_DATA_CORRUPTION
+ bool "Trigger a BUG when data corruption is detected"
+ select 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 3859bf63561c..7f7bfa55eb6d 100644
--- a/lib/list_debug.c
+++ b/lib/list_debug.c
@@ -2,8 +2,7 @@
* Copyright 2006, Red Hat, Inc., Dave Jones
* Released under the General Public License (GPL).
*
- * This file contains the linked list implementations for
- * DEBUG_LIST.
+ * This file contains the linked list validation for DEBUG_LIST.
*/
#include <linux/export.h>
@@ -13,88 +12,48 @@
#include <linux/rculist.h>
/*
- * Insert a new entry between two known consecutive entries.
- *
- * This is only for internal list manipulation where we know
- * the prev/next entries already!
+ * Check that the data structures for the list manipulations are reasonably
+ * valid. Failures here indicate memory corruption (and possibly an exploit
+ * attempt).
*/
-void __list_add(struct list_head *new,
- struct list_head *prev,
- struct list_head *next)
+bool __list_add_valid(struct list_head *new, struct list_head *prev,
+ struct list_head *next)
{
- WARN(next->prev != prev,
- "list_add corruption. next->prev should be "
- "prev (%p), but was %p. (next=%p).\n",
+ 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);
- WARN(prev->next != next,
- "list_add corruption. prev->next should be "
- "next (%p), but was %p. (prev=%p).\n",
+ 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);
- WARN(new == prev || new == next,
- "list_add double add: new=%p, prev=%p, next=%p.\n",
- new, prev, next);
- next->prev = new;
- new->next = next;
- new->prev = prev;
- WRITE_ONCE(prev->next, new);
+ 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);
+EXPORT_SYMBOL(__list_add_valid);
-void __list_del_entry(struct list_head *entry)
+bool __list_del_entry_valid(struct list_head *entry)
{
struct list_head *prev, *next;
prev = entry->prev;
next = entry->next;
- if (WARN(next == LIST_POISON1,
+ CHECK_DATA_CORRUPTION(next == LIST_POISON1,
"list_del corruption, %p->next is LIST_POISON1 (%p)\n",
- entry, LIST_POISON1) ||
- WARN(prev == LIST_POISON2,
+ entry, LIST_POISON1);
+ CHECK_DATA_CORRUPTION(prev == LIST_POISON2,
"list_del corruption, %p->prev is LIST_POISON2 (%p)\n",
- entry, LIST_POISON2) ||
- WARN(prev->next != entry,
- "list_del corruption. prev->next should be %p, "
- "but was %p\n", entry, prev->next) ||
- WARN(next->prev != entry,
- "list_del corruption. next->prev should be %p, "
- "but was %p\n", entry, next->prev))
- return;
-
- __list_del(prev, next);
-}
-EXPORT_SYMBOL(__list_del_entry);
+ 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;
-/**
- * list_del - deletes entry from list.
- * @entry: the element to delete from the list.
- * Note: list_empty on entry does not return true after this, the entry is
- * in an undefined state.
- */
-void list_del(struct list_head *entry)
-{
- __list_del_entry(entry);
- entry->next = LIST_POISON1;
- entry->prev = LIST_POISON2;
-}
-EXPORT_SYMBOL(list_del);
-
-/*
- * RCU variants.
- */
-void __list_add_rcu(struct list_head *new,
- struct list_head *prev, struct list_head *next)
-{
- WARN(next->prev != prev,
- "list_add_rcu corruption. next->prev should be prev (%p), but was %p. (next=%p).\n",
- prev, next->prev, next);
- WARN(prev->next != next,
- "list_add_rcu corruption. prev->next should be next (%p), but was %p. (prev=%p).\n",
- next, prev->next, prev);
- new->next = next;
- new->prev = prev;
- rcu_assign_pointer(list_next_rcu(prev), new);
- next->prev = new;
}
-EXPORT_SYMBOL(__list_add_rcu);
+EXPORT_SYMBOL(__list_del_entry_valid);