diff options
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/sched.h | 20 | ||||
| -rw-r--r-- | include/linux/signal.h | 4 | ||||
| -rw-r--r-- | include/uapi/linux/signal.h | 5 |
3 files changed, 28 insertions, 1 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index 8db05e4e06a6..e8dfa6f0d843 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1595,6 +1595,7 @@ struct task_struct { unsigned long sas_ss_sp; size_t sas_ss_size; + unsigned sas_ss_flags; struct callback_head *task_works; @@ -2574,6 +2575,18 @@ static inline int kill_cad_pid(int sig, int priv) */ static inline int on_sig_stack(unsigned long sp) { + /* + * If the signal stack is SS_AUTODISARM then, by construction, we + * can't be on the signal stack unless user code deliberately set + * SS_AUTODISARM when we were already on it. + * + * This improves reliability: if user state gets corrupted such that + * the stack pointer points very close to the end of the signal stack, + * then this check will enable the signal to be handled anyway. + */ + if (current->sas_ss_flags & SS_AUTODISARM) + return 0; + #ifdef CONFIG_STACK_GROWSUP return sp >= current->sas_ss_sp && sp - current->sas_ss_sp < current->sas_ss_size; @@ -2591,6 +2604,13 @@ static inline int sas_ss_flags(unsigned long sp) return on_sig_stack(sp) ? SS_ONSTACK : 0; } +static inline void sas_ss_reset(struct task_struct *p) +{ + p->sas_ss_sp = 0; + p->sas_ss_size = 0; + p->sas_ss_flags = SS_DISABLE; +} + static inline unsigned long sigsp(unsigned long sp, struct ksignal *ksig) { if (unlikely((ksig->ka.sa.sa_flags & SA_ONSTACK)) && ! sas_ss_flags(sp)) diff --git a/include/linux/signal.h b/include/linux/signal.h index 92557bbce7e7..3fbe81444d31 100644 --- a/include/linux/signal.h +++ b/include/linux/signal.h @@ -432,8 +432,10 @@ int __save_altstack(stack_t __user *, unsigned long); stack_t __user *__uss = uss; \ struct task_struct *t = current; \ put_user_ex((void __user *)t->sas_ss_sp, &__uss->ss_sp); \ - put_user_ex(sas_ss_flags(sp), &__uss->ss_flags); \ + put_user_ex(t->sas_ss_flags, &__uss->ss_flags); \ put_user_ex(t->sas_ss_size, &__uss->ss_size); \ + if (t->sas_ss_flags & SS_AUTODISARM) \ + sas_ss_reset(t); \ } while (0); #ifdef CONFIG_PROC_FS diff --git a/include/uapi/linux/signal.h b/include/uapi/linux/signal.h index e1bd50c29ded..cd0804b6bfa2 100644 --- a/include/uapi/linux/signal.h +++ b/include/uapi/linux/signal.h @@ -7,4 +7,9 @@ #define SS_ONSTACK 1 #define SS_DISABLE 2 +/* bit-flags */ +#define SS_AUTODISARM (1U << 31) /* disable sas during sighandling */ +/* mask for all SS_xxx flags */ +#define SS_FLAG_BITS SS_AUTODISARM + #endif /* _UAPI_LINUX_SIGNAL_H */ |