signal: Add an optional check for altstack size

[mirror_ubuntu-jammy-kernel.git] / kernel / signal.c

diff --git a/kernel/signal.c b/kernel/signal.c
index 6e3dbb3d12170c02ab5d768269de9c9626d2219c..0b6a9ab634ccf8e4e8632a0ddb9785242d4288b2 100644 (file)
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -4165,11 +4165,29 @@ int do_sigaction(int sig, struct k_sigaction *act, struct k_sigaction *oact)
        return 0;
 }
 
+#ifdef CONFIG_DYNAMIC_SIGFRAME
+static inline void sigaltstack_lock(void)
+       __acquires(&current->sighand->siglock)
+{
+       spin_lock_irq(&current->sighand->siglock);
+}
+
+static inline void sigaltstack_unlock(void)
+       __releases(&current->sighand->siglock)
+{
+       spin_unlock_irq(&current->sighand->siglock);
+}
+#else
+static inline void sigaltstack_lock(void) { }
+static inline void sigaltstack_unlock(void) { }
+#endif
+
 static int
 do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
                size_t min_ss_size)
 {
        struct task_struct *t = current;
+       int ret = 0;
 
        if (oss) {
                memset(oss, 0, sizeof(stack_t));
@@ -4193,19 +4211,24 @@ do_sigaltstack (const stack_t *ss, stack_t *oss, unsigned long sp,
                                ss_mode != 0))
                        return -EINVAL;
 
+               sigaltstack_lock();
                if (ss_mode == SS_DISABLE) {
                        ss_size = 0;
                        ss_sp = NULL;
                } else {
                        if (unlikely(ss_size < min_ss_size))
-                               return -ENOMEM;
+                               ret = -ENOMEM;
+                       if (!sigaltstack_size_valid(ss_size))
+                               ret = -ENOMEM;
                }
-
-               t->sas_ss_sp = (unsigned long) ss_sp;
-               t->sas_ss_size = ss_size;
-               t->sas_ss_flags = ss_flags;
+               if (!ret) {
+                       t->sas_ss_sp = (unsigned long) ss_sp;
+                       t->sas_ss_size = ss_size;
+                       t->sas_ss_flags = ss_flags;
+               }
+               sigaltstack_unlock();
        }
-       return 0;
+       return ret;
 }
 
 SYSCALL_DEFINE2(sigaltstack,const stack_t __user *,uss, stack_t __user *,uoss)