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Merge branch 'core-signals-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

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Pull core signal updates from Ingo Molnar:
 "These updates from Stas Sergeev and Andy Lutomirski, improve the
  sigaltstack interface by extending its ABI with the SS_AUTODISARM
  feature, which makes it possible to use swapcontext() in a sighandler
  that works on sigaltstack.  Without this flag, the subsequent signal
  will corrupt the state of the switched-away sighandler.

  The inspiration is more robust dosemu signal handling"

* 'core-signals-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  signals/sigaltstack: Change SS_AUTODISARM to (1U << 31)
  signals/sigaltstack: Report current flag bits in sigaltstack()
  selftests/sigaltstack: Fix the sigaltstack test on old kernels
  signals/sigaltstack: If SS_AUTODISARM, bypass on_sig_stack()
  selftests/sigaltstack: Add new testcase for sigaltstack(SS_ONSTACK|SS_AUTODISARM)
  signals/sigaltstack: Implement SS_AUTODISARM flag
  signals/sigaltstack: Prepare to add new SS_xxx flags
  signals/sigaltstack, x86/signals: Unify the x86 sigaltstack check with other architectures
This commit is contained in:
Linus Torvalds
2016-05-16 12:25:25 -07:00
parent a3871bd434 91c6180572
commit 230e51f211
9 changed files with 241 additions and 27 deletions
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20
include/linux/sched.h
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@@ -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))