Messages in this thread | | | Date | Tue, 16 Aug 2016 14:26:05 -0700 | From | "Paul E. McKenney" <> | Subject | Re: [PATCH 4/5] bug: Provide toggle for BUG on data corruption |
| |
On Tue, Aug 16, 2016 at 02:11:04PM -0700, Kees Cook wrote: > The kernel checks for several cases of data structure corruption under > either normal runtime, or under various CONFIG_DEBUG_* settings. When > corruption is detected, some systems may want to BUG() immediately instead > of letting the corruption continue. Many of these manipulation primitives > can be used by security flaws to gain arbitrary memory write control. This > provides CONFIG_BUG_ON_CORRUPTION to control newly added BUG() locations. > > This is inspired by similar hardening in PaX and Grsecurity, and by > Stephen Boyd in MSM kernels. > > Signed-off-by: Kees Cook <keescook@chromium.org>
OK, I will bite... Why both the WARN() and the BUG_ON()?
Thanx, Paul
> --- > include/linux/bug.h | 7 +++++++ > kernel/locking/spinlock_debug.c | 1 + > kernel/workqueue.c | 2 ++ > lib/Kconfig.debug | 10 ++++++++++ > lib/list_debug.c | 7 +++++++ > 5 files changed, 27 insertions(+) > > diff --git a/include/linux/bug.h b/include/linux/bug.h > index e51b0709e78d..7e69758dd798 100644 > --- a/include/linux/bug.h > +++ b/include/linux/bug.h > @@ -118,4 +118,11 @@ static inline enum bug_trap_type report_bug(unsigned long bug_addr, > } > > #endif /* CONFIG_GENERIC_BUG */ > + > +#ifdef CONFIG_BUG_ON_CORRUPTION > +# define CORRUPTED_DATA_STRUCTURE true > +#else > +# define CORRUPTED_DATA_STRUCTURE false > +#endif > + > #endif /* _LINUX_BUG_H */ > diff --git a/kernel/locking/spinlock_debug.c b/kernel/locking/spinlock_debug.c > index 0374a596cffa..d5f833769feb 100644 > --- a/kernel/locking/spinlock_debug.c > +++ b/kernel/locking/spinlock_debug.c > @@ -64,6 +64,7 @@ static void spin_dump(raw_spinlock_t *lock, const char *msg) > owner ? owner->comm : "<none>", > owner ? task_pid_nr(owner) : -1, > lock->owner_cpu); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > dump_stack(); > } > > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > index ef071ca73fc3..ea0132b55eca 100644 > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -48,6 +48,7 @@ > #include <linux/nodemask.h> > #include <linux/moduleparam.h> > #include <linux/uaccess.h> > +#include <linux/bug.h> > > #include "workqueue_internal.h" > > @@ -2108,6 +2109,7 @@ __acquires(&pool->lock) > current->comm, preempt_count(), task_pid_nr(current), > worker->current_func); > debug_show_held_locks(current); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > dump_stack(); > } > > diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug > index 2307d7c89dac..d64bd6b6fd45 100644 > --- a/lib/Kconfig.debug > +++ b/lib/Kconfig.debug > @@ -1987,6 +1987,16 @@ config TEST_STATIC_KEYS > > If unsure, say N. > > +config BUG_ON_CORRUPTION > + bool "Trigger a BUG when data corruption is detected" > + help > + Select this option if the kernel should BUG when it encounters > + data corruption in various kernel memory structures during checks > + added by options like CONFIG_DEBUG_LIST, CONFIG_DEBUG_SPINLOCK, > + etc. > + > + If unsure, say N. > + > source "samples/Kconfig" > > source "lib/Kconfig.kgdb" > diff --git a/lib/list_debug.c b/lib/list_debug.c > index 80e2e40a6a4e..161c7e7d3478 100644 > --- a/lib/list_debug.c > +++ b/lib/list_debug.c > @@ -26,16 +26,19 @@ bool __list_add_debug(struct list_head *new, > 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); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > 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); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > return false; > } > if (unlikely(new == prev || new == next)) { > WARN(1, "list_add double add: new=%p, prev=%p, next=%p.\n", > new, prev, next); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > return false; > } > return true; > @@ -52,21 +55,25 @@ bool __list_del_entry_debug(struct list_head *entry) > if (unlikely(next == LIST_POISON1)) { > WARN(1, "list_del corruption, %p->next is LIST_POISON1 (%p)\n", > entry, LIST_POISON1); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > return false; > } > if (unlikely(prev == LIST_POISON2)) { > WARN(1, "list_del corruption, %p->prev is LIST_POISON2 (%p)\n", > entry, LIST_POISON2); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > return false; > } > if (unlikely(prev->next != entry)) { > WARN(1, "list_del corruption. prev->next should be %p, but was %p\n", > entry, prev->next); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > return false; > } > if (unlikely(next->prev != entry)) { > WARN(1, "list_del corruption. next->prev should be %p, but was %p\n", > entry, next->prev); > + BUG_ON(CORRUPTED_DATA_STRUCTURE); > return false; > } > return true; > -- > 2.7.4 >
| |