From: Jason Baron register_kprobe() downs the 'text_mutex' and then calls jump_label_text_reserved(), which downs the 'jump_label_mutex'. However, the jump label code takes those mutexes in the reverse order. Fix by requiring the caller of jump_label_text_reserved() to do the jump label locking via the newly added: jump_label_lock(), jump_label_unlock(). Currently, kprobes is the only user of jump_label_text_reserved(). Reported-by: Ingo Molnar Acked-by: Masami Hiramatsu Signed-off-by: Jason Baron LKML-Reference: <759032c48d5e30c27f0bba003d09bffa8e9f28bb.1285965957.git.jbaron@redhat.com> Signed-off-by: Steven Rostedt --- include/linux/jump_label.h | 5 +++++ kernel/jump_label.c | 33 +++++++++++++++++++++------------ kernel/kprobes.c | 6 ++++++ 3 files changed, 32 insertions(+), 12 deletions(-) diff --git a/include/linux/jump_label.h b/include/linux/jump_label.h index b72cd9f..cf213d1 100644 --- a/include/linux/jump_label.h +++ b/include/linux/jump_label.h @@ -18,6 +18,8 @@ struct module; extern struct jump_entry __start___jump_table[]; extern struct jump_entry __stop___jump_table[]; +extern void jump_label_lock(void); +extern void jump_label_unlock(void); extern void arch_jump_label_transform(struct jump_entry *entry, enum jump_label_type type); extern void arch_jump_label_text_poke_early(jump_label_t addr); @@ -59,6 +61,9 @@ static inline int jump_label_text_reserved(void *start, void *end) return 0; } +static inline void jump_label_lock(void) {} +static inline void jump_label_unlock(void) {} + #endif #endif diff --git a/kernel/jump_label.c b/kernel/jump_label.c index be9e105..12cce78 100644 --- a/kernel/jump_label.c +++ b/kernel/jump_label.c @@ -39,6 +39,16 @@ struct jump_label_module_entry { struct module *mod; }; +void jump_label_lock(void) +{ + mutex_lock(&jump_label_mutex); +} + +void jump_label_unlock(void) +{ + mutex_unlock(&jump_label_mutex); +} + static int jump_label_cmp(const void *a, const void *b) { const struct jump_entry *jea = a; @@ -152,7 +162,7 @@ void jump_label_update(unsigned long key, enum jump_label_type type) struct jump_label_module_entry *e_module; int count; - mutex_lock(&jump_label_mutex); + jump_label_lock(); entry = get_jump_label_entry((jump_label_t)key); if (entry) { count = entry->nr_entries; @@ -175,7 +185,7 @@ void jump_label_update(unsigned long key, enum jump_label_type type) } } } - mutex_unlock(&jump_label_mutex); + jump_label_unlock(); } static int addr_conflict(struct jump_entry *entry, void *start, void *end) @@ -232,6 +242,7 @@ out: * overlaps with any of the jump label patch addresses. Code * that wants to modify kernel text should first verify that * it does not overlap with any of the jump label addresses. + * Caller must hold jump_label_mutex. * * returns 1 if there is an overlap, 0 otherwise */ @@ -242,7 +253,6 @@ int jump_label_text_reserved(void *start, void *end) struct jump_entry *iter_stop = __start___jump_table; int conflict = 0; - mutex_lock(&jump_label_mutex); iter = iter_start; while (iter < iter_stop) { if (addr_conflict(iter, start, end)) { @@ -257,7 +267,6 @@ int jump_label_text_reserved(void *start, void *end) conflict = module_conflict(start, end); #endif out: - mutex_unlock(&jump_label_mutex); return conflict; } @@ -268,7 +277,7 @@ static __init int init_jump_label(void) struct jump_entry *iter_stop = __stop___jump_table; struct jump_entry *iter; - mutex_lock(&jump_label_mutex); + jump_label_lock(); ret = build_jump_label_hashtable(__start___jump_table, __stop___jump_table); iter = iter_start; @@ -276,7 +285,7 @@ static __init int init_jump_label(void) arch_jump_label_text_poke_early(iter->code); iter++; } - mutex_unlock(&jump_label_mutex); + jump_label_unlock(); return ret; } early_initcall(init_jump_label); @@ -409,21 +418,21 @@ jump_label_module_notify(struct notifier_block *self, unsigned long val, switch (val) { case MODULE_STATE_COMING: - mutex_lock(&jump_label_mutex); + jump_label_lock(); ret = add_jump_label_module(mod); if (ret) remove_jump_label_module(mod); - mutex_unlock(&jump_label_mutex); + jump_label_unlock(); break; case MODULE_STATE_GOING: - mutex_lock(&jump_label_mutex); + jump_label_lock(); remove_jump_label_module(mod); - mutex_unlock(&jump_label_mutex); + jump_label_unlock(); break; case MODULE_STATE_LIVE: - mutex_lock(&jump_label_mutex); + jump_label_lock(); remove_jump_label_module_init(mod); - mutex_unlock(&jump_label_mutex); + jump_label_unlock(); break; } return ret; diff --git a/kernel/kprobes.c b/kernel/kprobes.c index ec4210c..d45d72e 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1145,13 +1145,16 @@ int __kprobes register_kprobe(struct kprobe *p) return ret; preempt_disable(); + jump_label_lock(); if (!kernel_text_address((unsigned long) p->addr) || in_kprobes_functions((unsigned long) p->addr) || ftrace_text_reserved(p->addr, p->addr) || jump_label_text_reserved(p->addr, p->addr)) { preempt_enable(); + jump_label_unlock(); return -EINVAL; } + jump_label_unlock(); /* User can pass only KPROBE_FLAG_DISABLED to register_kprobe */ p->flags &= KPROBE_FLAG_DISABLED; @@ -1186,6 +1189,8 @@ int __kprobes register_kprobe(struct kprobe *p) INIT_LIST_HEAD(&p->list); mutex_lock(&kprobe_mutex); + jump_label_lock(); /* needed to call jump_label_text_reserved() */ + get_online_cpus(); /* For avoiding text_mutex deadlock. */ mutex_lock(&text_mutex); @@ -1213,6 +1218,7 @@ int __kprobes register_kprobe(struct kprobe *p) out: mutex_unlock(&text_mutex); put_online_cpus(); + jump_label_unlock(); mutex_unlock(&kprobe_mutex); if (probed_mod) -- 1.7.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/