From: Joonsoo Kim <[email protected]> Since there is a different callpath even in the vchecker, static skip value doesn't always exclude vchecker's stacktrace. Fix it through checking stacktrace dynamically.
v2: skip two depth of stack at default, it's safe! Signed-off-by: Joonsoo Kim <[email protected]> --- mm/kasan/vchecker.c | 41 +++++++++++++++++++++++++---------------- 1 file changed, 25 insertions(+), 16 deletions(-) diff --git a/mm/kasan/vchecker.c b/mm/kasan/vchecker.c index df480d5..dc3a9a7 100644 --- a/mm/kasan/vchecker.c +++ b/mm/kasan/vchecker.c @@ -23,6 +23,7 @@ #include "kasan.h" #define VCHECKER_STACK_DEPTH (16) +#define VCHECKER_SKIP_DEPTH (2) struct vchecker { bool enabled; @@ -48,7 +49,7 @@ struct vchecker_type { void (*show)(struct kmem_cache *s, struct seq_file *f, struct vchecker_cb *cb, void *object, bool verbose); bool (*check)(struct kmem_cache *s, struct vchecker_cb *cb, - void *object, bool write, + void *object, bool write, unsigned long ret_ip, unsigned long begin, unsigned long end); }; @@ -276,7 +277,7 @@ bool vchecker_check(unsigned long addr, size_t size, continue; checked = true; - if (cb->type->check(s, cb, object, write, begin, end)) + if (cb->type->check(s, cb, object, write, ret_ip, begin, end)) continue; vchecker_report(addr, size, write, ret_ip, s, cb, object); @@ -292,14 +293,29 @@ bool vchecker_check(unsigned long addr, size_t size, return vchecker_poisoned((void *)addr, size); } -static noinline depot_stack_handle_t save_stack(int skip, bool *is_new) +static void filter_vchecker_stacks(struct stack_trace *trace, + unsigned long ret_ip) +{ + int i; + + for (i = 0; i < trace->nr_entries; i++) { + if (trace->entries[i] == ret_ip) { + trace->entries = &trace->entries[i]; + trace->nr_entries -= i; + break; + } + } +} + +static noinline depot_stack_handle_t save_stack(unsigned long ret_ip, + bool *is_new) { unsigned long entries[VCHECKER_STACK_DEPTH]; struct stack_trace trace = { .nr_entries = 0, .entries = entries, .max_entries = VCHECKER_STACK_DEPTH, - .skip = skip, + .skip = VCHECKER_SKIP_DEPTH, }; depot_stack_handle_t handle; @@ -311,6 +327,7 @@ static noinline depot_stack_handle_t save_stack(int skip, bool *is_new) if (trace.nr_entries == 0) return 0; + filter_vchecker_stacks(&trace, ret_ip); handle = depot_save_stack(NULL, &trace, __GFP_ATOMIC, is_new); WARN_ON(!handle); @@ -542,7 +559,7 @@ static void show_value(struct kmem_cache *s, struct seq_file *f, } static bool check_value(struct kmem_cache *s, struct vchecker_cb *cb, - void *object, bool write, + void *object, bool write, unsigned long ret_ip, unsigned long begin, unsigned long end) { struct vchecker_value_arg *arg; @@ -553,7 +570,7 @@ static bool check_value(struct kmem_cache *s, struct vchecker_cb *cb, if (!write) goto check; - handle = save_stack(0, NULL); + handle = save_stack(ret_ip, NULL); if (!handle) { pr_err("VCHECKER: %s: fail at addr %p\n", __func__, object); dump_stack(); @@ -679,16 +696,8 @@ static void show_callstack(struct kmem_cache *s, struct seq_file *f, } } -/* - * number of stacks to skip (at least). - * - * __asan_loadX -> vchecker_check -> cb->check() -> save_stack - * -> save_stack_trace - */ -#define STACK_SKIP 5 - static bool check_callstack(struct kmem_cache *s, struct vchecker_cb *cb, - void *object, bool write, + void *object, bool write, unsigned long ret_ip, unsigned long begin, unsigned long end) { u32 handle; @@ -696,7 +705,7 @@ static bool check_callstack(struct kmem_cache *s, struct vchecker_cb *cb, struct vchecker_callstack_arg *arg = cb->arg; int idx; - handle = save_stack(STACK_SKIP, &is_new); + handle = save_stack(ret_ip, &is_new); if (!is_new) return true; -- 2.7.4
