syscal_exec16: Fix two bugs

1. Potential race on reference to hdr
2. If we tried to exec an r/o file and failed we could end up being marked
non coredumping

diff --git a/Kernel/syscall_exec16.c b/Kernel/syscall_exec16.c
index 968695f..78f4945 100644 (file)
--- a/Kernel/syscall_exec16.c
+++ b/Kernel/syscall_exec16.c
@@ -47,7 +47,7 @@ static int header_ok(uint8_t *pp)
 arg_t _execve(void)
 {
        /* We aren't re-entrant where this matters */
-       staticfast uint8_t hdr[16];
+       uint8_t hdr[16];
        staticfast inoptr ino;
        char **nargv;           /* In user space */
        char **nenvp;           /* In user space */
@@ -71,16 +71,6 @@ arg_t _execve(void)
                goto nogood;
        }
 
-       /* Core dump and ptrace permission logic */
-#ifdef CONFIG_LEVEL_2
-       /* Q: should uid == 0 mean we always allow core */
-       if ((!(getperm(ino) & OTH_RD)) ||
-               (ino->c_node.i_mode & (SET_UID | SET_GID)))
-               udata.u_flags |= U_FLAG_NOCORE;
-       else
-               udata.u_flags &= ~U_FLAG_NOCORE;
-#endif
-
        setftime(ino, A_TIME);
 
        udata.u_offset = 0;
@@ -139,6 +129,16 @@ arg_t _execve(void)
                goto nogood3;
 
        /* From this point on we are commmited to the exec() completing */
+
+       /* Core dump and ptrace permission logic */
+#ifdef CONFIG_LEVEL_2
+       /* Q: should uid == 0 mean we always allow core */
+       if ((!(getperm(ino) & OTH_RD)) ||
+               (ino->c_node.i_mode & (SET_UID | SET_GID)))
+               udata.u_flags |= U_FLAG_NOCORE;
+       else
+               udata.u_flags &= ~U_FLAG_NOCORE;
+#endif
        udata.u_top = top;
        udata.u_ptab->p_top = top;