From aedcade6f4fa9a1e65f327fc42de3fb47660646c Mon Sep 17 00:00:00 2001 From: Stephen Boyd Date: Fri, 14 Aug 2020 17:40:26 -0700 Subject: debugobjects: Allow debug_obj_descr to be const The debugobject core could be slightly harder to corrupt if the debug_obj_descr would be a pointer to const memory. Depending on the architecture, const data structures are placed into read-only memory and thus are harder to corrupt or hijack. This descriptor is used to fix up stuff like timers and workqueues when core kernel data structures are busted, so moving the descriptors to read-only memory will make debugobjects more resilient to something going wrong and then corrupting the function pointers inside struct debug_obj_descr. Signed-off-by: Stephen Boyd Signed-off-by: Thomas Gleixner Reviewed-by: Kees Cook Link: https://lore.kernel.org/r/20200815004027.2046113-2-swboyd@chromium.org --- include/linux/debugobjects.h | 32 ++++++++++++++++---------------- 1 file changed, 16 insertions(+), 16 deletions(-) (limited to 'include') diff --git a/include/linux/debugobjects.h b/include/linux/debugobjects.h index afc416e5dcab..8d2dde23e9fb 100644 --- a/include/linux/debugobjects.h +++ b/include/linux/debugobjects.h @@ -30,7 +30,7 @@ struct debug_obj { enum debug_obj_state state; unsigned int astate; void *object; - struct debug_obj_descr *descr; + const struct debug_obj_descr *descr; }; /** @@ -64,14 +64,14 @@ struct debug_obj_descr { }; #ifdef CONFIG_DEBUG_OBJECTS -extern void debug_object_init (void *addr, struct debug_obj_descr *descr); +extern void debug_object_init (void *addr, const struct debug_obj_descr *descr); extern void -debug_object_init_on_stack(void *addr, struct debug_obj_descr *descr); -extern int debug_object_activate (void *addr, struct debug_obj_descr *descr); -extern void debug_object_deactivate(void *addr, struct debug_obj_descr *descr); -extern void debug_object_destroy (void *addr, struct debug_obj_descr *descr); -extern void debug_object_free (void *addr, struct debug_obj_descr *descr); -extern void debug_object_assert_init(void *addr, struct debug_obj_descr *descr); +debug_object_init_on_stack(void *addr, const struct debug_obj_descr *descr); +extern int debug_object_activate (void *addr, const struct debug_obj_descr *descr); +extern void debug_object_deactivate(void *addr, const struct debug_obj_descr *descr); +extern void debug_object_destroy (void *addr, const struct debug_obj_descr *descr); +extern void debug_object_free (void *addr, const struct debug_obj_descr *descr); +extern void debug_object_assert_init(void *addr, const struct debug_obj_descr *descr); /* * Active state: @@ -79,26 +79,26 @@ extern void debug_object_assert_init(void *addr, struct debug_obj_descr *descr); * - Must return to 0 before deactivation. */ extern void -debug_object_active_state(void *addr, struct debug_obj_descr *descr, +debug_object_active_state(void *addr, const struct debug_obj_descr *descr, unsigned int expect, unsigned int next); extern void debug_objects_early_init(void); extern void debug_objects_mem_init(void); #else static inline void -debug_object_init (void *addr, struct debug_obj_descr *descr) { } +debug_object_init (void *addr, const struct debug_obj_descr *descr) { } static inline void -debug_object_init_on_stack(void *addr, struct debug_obj_descr *descr) { } +debug_object_init_on_stack(void *addr, const struct debug_obj_descr *descr) { } static inline int -debug_object_activate (void *addr, struct debug_obj_descr *descr) { return 0; } +debug_object_activate (void *addr, const struct debug_obj_descr *descr) { return 0; } static inline void -debug_object_deactivate(void *addr, struct debug_obj_descr *descr) { } +debug_object_deactivate(void *addr, const struct debug_obj_descr *descr) { } static inline void -debug_object_destroy (void *addr, struct debug_obj_descr *descr) { } +debug_object_destroy (void *addr, const struct debug_obj_descr *descr) { } static inline void -debug_object_free (void *addr, struct debug_obj_descr *descr) { } +debug_object_free (void *addr, const struct debug_obj_descr *descr) { } static inline void -debug_object_assert_init(void *addr, struct debug_obj_descr *descr) { } +debug_object_assert_init(void *addr, const struct debug_obj_descr *descr) { } static inline void debug_objects_early_init(void) { } static inline void debug_objects_mem_init(void) { } -- cgit From 88451f2cd3cec2abc30debdf129422d2699d1eba Mon Sep 17 00:00:00 2001 From: Zqiang Date: Tue, 8 Sep 2020 14:27:09 +0800 Subject: debugobjects: Free per CPU pool after CPU unplug If a CPU is offlined the debug objects per CPU pool is not cleaned up. If the CPU is never onlined again then the objects in the pool are wasted. Add a CPU hotplug callback which is invoked after the CPU is dead to free the pool. [ tglx: Massaged changelog and added comment about remote access safety ] Signed-off-by: Zqiang Signed-off-by: Thomas Gleixner Cc: Waiman Long Link: https://lore.kernel.org/r/20200908062709.11441-1-qiang.zhang@windriver.com --- include/linux/cpuhotplug.h | 1 + lib/debugobjects.c | 25 +++++++++++++++++++++++++ 2 files changed, 26 insertions(+) (limited to 'include') diff --git a/include/linux/cpuhotplug.h b/include/linux/cpuhotplug.h index bf9181cef444..6f524bbf71a2 100644 --- a/include/linux/cpuhotplug.h +++ b/include/linux/cpuhotplug.h @@ -36,6 +36,7 @@ enum cpuhp_state { CPUHP_X86_MCE_DEAD, CPUHP_VIRT_NET_DEAD, CPUHP_SLUB_DEAD, + CPUHP_DEBUG_OBJ_DEAD, CPUHP_MM_WRITEBACK_DEAD, CPUHP_MM_VMSTAT_DEAD, CPUHP_SOFTIRQ_DEAD, diff --git a/lib/debugobjects.c b/lib/debugobjects.c index e2a3171b6c63..9e14ae02306b 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -19,6 +19,7 @@ #include #include #include +#include #define ODEBUG_HASH_BITS 14 #define ODEBUG_HASH_SIZE (1 << ODEBUG_HASH_BITS) @@ -433,6 +434,25 @@ static void free_object(struct debug_obj *obj) } } +#ifdef CONFIG_HOTPLUG_CPU +static int object_cpu_offline(unsigned int cpu) +{ + struct debug_percpu_free *percpu_pool; + struct hlist_node *tmp; + struct debug_obj *obj; + + /* Remote access is safe as the CPU is dead already */ + percpu_pool = per_cpu_ptr(&percpu_obj_pool, cpu); + hlist_for_each_entry_safe(obj, tmp, &percpu_pool->free_objs, node) { + hlist_del(&obj->node); + kmem_cache_free(obj_cache, obj); + } + percpu_pool->obj_free = 0; + + return 0; +} +#endif + /* * We run out of memory. That means we probably have tons of objects * allocated. @@ -1367,6 +1387,11 @@ void __init debug_objects_mem_init(void) } else debug_objects_selftest(); +#ifdef CONFIG_HOTPLUG_CPU + cpuhp_setup_state_nocalls(CPUHP_DEBUG_OBJ_DEAD, "object:offline", NULL, + object_cpu_offline); +#endif + /* * Increase the thresholds for allocating and freeing objects * according to the number of possible CPUs available in the system. -- cgit