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authorAl Viro <viro@zeniv.linux.org.uk>2017-05-27 00:29:34 -0400
committerAl Viro <viro@zeniv.linux.org.uk>2017-05-27 15:38:17 -0400
commitbcfe8ad8ef55a1cf3c935c2667e8e5ae598b3b7e (patch)
treeb94e3ebf18142c1c2fde4d7d1da4d68035100b86 /kernel/signal.c
parent613763a1f056211522bac77ff39f25706e678fdd (diff)
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do_sigaltstack(): lift copying to/from userland into callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'kernel/signal.c')
-rw-r--r--kernel/signal.c107
1 files changed, 46 insertions, 61 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index ca92bcfeb322..d1eed0d7ca64 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3113,78 +3113,68 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
}
static int
-do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long sp)
+do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp)
{
- stack_t oss;
- int error;
+ struct task_struct *t = current;
- oss.ss_sp = (void __user *) current->sas_ss_sp;
- oss.ss_size = current->sas_ss_size;
- oss.ss_flags = sas_ss_flags(sp) |
- (current->sas_ss_flags & SS_FLAG_BITS);
+ if (oss) {
+ memset(oss, 0, sizeof(stack_t));
+ oss->ss_sp = (void __user *) t->sas_ss_sp;
+ oss->ss_size = t->sas_ss_size;
+ oss->ss_flags = sas_ss_flags(sp) |
+ (current->sas_ss_flags & SS_FLAG_BITS);
+ }
- if (uss) {
- void __user *ss_sp;
- size_t ss_size;
- unsigned ss_flags;
+ if (ss) {
+ void __user *ss_sp = ss->ss_sp;
+ size_t ss_size = ss->ss_size;
+ unsigned ss_flags = ss->ss_flags;
int ss_mode;
- error = -EFAULT;
- if (!access_ok(VERIFY_READ, uss, sizeof(*uss)))
- goto out;
- error = __get_user(ss_sp, &uss->ss_sp) |
- __get_user(ss_flags, &uss->ss_flags) |
- __get_user(ss_size, &uss->ss_size);
- if (error)
- goto out;
-
- error = -EPERM;
- if (on_sig_stack(sp))
- goto out;
+ if (unlikely(on_sig_stack(sp)))
+ return -EPERM;
ss_mode = ss_flags & ~SS_FLAG_BITS;
- error = -EINVAL;
- if (ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
- ss_mode != 0)
- goto out;
+ if (unlikely(ss_mode != SS_DISABLE && ss_mode != SS_ONSTACK &&
+ ss_mode != 0))
+ return -EINVAL;
if (ss_mode == SS_DISABLE) {
ss_size = 0;
ss_sp = NULL;
} else {
- error = -ENOMEM;
- if (ss_size < MINSIGSTKSZ)
- goto out;
+ if (unlikely(ss_size < MINSIGSTKSZ))
+ return -ENOMEM;
}
- current->sas_ss_sp = (unsigned long) ss_sp;
- current->sas_ss_size = ss_size;
- current->sas_ss_flags = ss_flags;
- }
-
- error = 0;
- if (uoss) {
- error = -EFAULT;
- if (!access_ok(VERIFY_WRITE, uoss, sizeof(*uoss)))
- goto out;
- error = __put_user(oss.ss_sp, &uoss->ss_sp) |
- __put_user(oss.ss_size, &uoss->ss_size) |
- __put_user(oss.ss_flags, &uoss->ss_flags);
+ t->sas_ss_sp = (unsigned long) ss_sp;
+ t->sas_ss_size = ss_size;
+ t->sas_ss_flags = ss_flags;
}
-
-out:
- return error;
+ return 0;
}
+
SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)
{
- return do_sigaltstack(uss, uoss, current_user_stack_pointer());
+ stack_t new, old;
+ int err;
+ if (uss && copy_from_user(&new, uss, sizeof(stack_t)))
+ return -EFAULT;
+ err = do_sigaltstack(uss ? &new : NULL, uoss ? &old : NULL,
+ current_user_stack_pointer());
+ if (!err && uoss && copy_to_user(uoss, &old, sizeof(stack_t)))
+ err = -EFAULT;
+ return err;
}
int restore_altstack(const stack_t __user *uss)
{
- int err = do_sigaltstack(uss, NULL, current_user_stack_pointer());
+ stack_t new;
+ if (copy_from_user(&new, uss, sizeof(stack_t)))
+ return -EFAULT;
+ (void)do_sigaltstack(&new, NULL, current_user_stack_pointer());
/* squash all but EFAULT for now */
- return err == -EFAULT ? err : 0;
+ return 0;
}
int __save_altstack(stack_t __user *uss, unsigned long sp)
@@ -3207,29 +3197,24 @@ COMPAT_SYSCALL_DEFINE2(sigaltstack,
{
stack_t uss, uoss;
int ret;
- mm_segment_t seg;
if (uss_ptr) {
compat_stack_t uss32;
-
- memset(&uss, 0, sizeof(stack_t));
if (copy_from_user(&uss32, uss_ptr, sizeof(compat_stack_t)))
return -EFAULT;
uss.ss_sp = compat_ptr(uss32.ss_sp);
uss.ss_flags = uss32.ss_flags;
uss.ss_size = uss32.ss_size;
}
- seg = get_fs();
- set_fs(KERNEL_DS);
- ret = do_sigaltstack((stack_t __force __user *) (uss_ptr ? &uss : NULL),
- (stack_t __force __user *) &uoss,
+ ret = do_sigaltstack(uss_ptr ? &uss : NULL, &uoss,
compat_user_stack_pointer());
- set_fs(seg);
if (ret >= 0 && uoss_ptr) {
- if (!access_ok(VERIFY_WRITE, uoss_ptr, sizeof(compat_stack_t)) ||
- __put_user(ptr_to_compat(uoss.ss_sp), &uoss_ptr->ss_sp) ||
- __put_user(uoss.ss_flags, &uoss_ptr->ss_flags) ||
- __put_user(uoss.ss_size, &uoss_ptr->ss_size))
+ compat_stack_t old;
+ memset(&old, 0, sizeof(old));
+ old.ss_sp = ptr_to_compat(uoss.ss_sp);
+ old.ss_flags = uoss.ss_flags;
+ old.ss_size = uoss.ss_size;
+ if (copy_to_user(uoss_ptr, &old, sizeof(compat_stack_t)))
ret = -EFAULT;
}
return ret;