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authorLinus Torvalds <torvalds@linux-foundation.org>2016-05-16 12:25:25 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-16 12:25:25 -0700
commit230e51f21101e49c8d73018d414adbd0d57459a1 (patch)
tree95dbb338a2ae90c0f8a060836bf93d858425e00a /kernel
parenta3871bd434cfc313cdcd1edc433507298f4aa928 (diff)
parent91c6180572e2fec71701d646ffc40ad30986275c (diff)
downloadlinux-230e51f21101e49c8d73018d414adbd0d57459a1.tar.bz2
Merge branch 'core-signals-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/fork.c2
-rw-r--r--kernel/signal.c29
2 files changed, 17 insertions, 14 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index d277e83ed3e0..3e8451527cbe 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1494,7 +1494,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
* sigaltstack should be cleared when sharing the same VM
*/
if ((clone_flags & (CLONE_VM|CLONE_VFORK)) == CLONE_VM)
- p->sas_ss_sp = p->sas_ss_size = 0;
+ sas_ss_reset(p);
/*
* Syscall tracing and stepping should be turned off in the
diff --git a/kernel/signal.c b/kernel/signal.c
index aa9bf00749c1..ab122a2cee41 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3099,12 +3099,14 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
oss.ss_sp = (void __user *) current->sas_ss_sp;
oss.ss_size = current->sas_ss_size;
- oss.ss_flags = sas_ss_flags(sp);
+ oss.ss_flags = sas_ss_flags(sp) |
+ (current->sas_ss_flags & SS_FLAG_BITS);
if (uss) {
void __user *ss_sp;
size_t ss_size;
- int ss_flags;
+ unsigned ss_flags;
+ int ss_mode;
error = -EFAULT;
if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
@@ -3119,18 +3121,13 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
if (on_sig_stack(sp))
goto out;
+ ss_mode = ss_flags & ~SS_FLAG_BITS;
error = -EINVAL;
- /*
- * Note - this code used to test ss_flags incorrectly:
- * old code may have been written using ss_flags==0
- * to mean ss_flags==SS_ONSTACK (as this was the only
- * way that worked) - this fix preserves that older
- * mechanism.
- */
- if (ss_flags != SS_DISABLE && ss_flags != SS_ONSTACK && ss_flags != 0)
+ if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
+ ss_mode != 0)
goto out;
- if (ss_flags == SS_DISABLE) {
+ if (ss_mode == SS_DISABLE) {
ss_size = 0;
ss_sp = NULL;
} else {
@@ -3141,6 +3138,7 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s
current->sas_ss_sp = (unsigned long) ss_sp;
current->sas_ss_size = ss_size;
+ current->sas_ss_flags = ss_flags;
}
error = 0;
@@ -3171,9 +3169,14 @@ int restore_altstack(const stack_t __user *uss)
int __save_altstack(stack_t __user *uss, unsigned long sp)
{
struct task_struct *t = current;
- return __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
- __put_user(sas_ss_flags(sp), &uss->ss_flags) |
+ int err = __put_user((void __user *)t->sas_ss_sp, &uss->ss_sp) |
+ __put_user(t->sas_ss_flags, &uss->ss_flags) |
__put_user(t->sas_ss_size, &uss->ss_size);
+ if (err)
+ return err;
+ if (t->sas_ss_flags & SS_AUTODISARM)
+ sas_ss_reset(t);
+ return 0;
}
#ifdef CONFIG_COMPAT