arc: don't leak bits of kernel stack into coredump

commit 7798bf2140ebcc36eafec6a4194fffd8d585d471 upstream.

On faulting sigreturn we do get SIGSEGV, all right, but anything
we'd put into pt_regs could end up in the coredump.  And since
__copy_from_user() never zeroed on arc, we'd better bugger off
on its failure without copying random uninitialized bits of
kernel stack into pt_regs...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index 6763654239a22979bbf21649f07e9bb2edfbdf5c..0823087dc9c0809e38e8eca7b28c1c82ae2d399d 100644 (file)
--- a/arch/arc/kernel/signal.c
+++ b/arch/arc/kernel/signal.c
@@ -80,13 +80,14 @@ static int restore_usr_regs(struct pt_regs *regs, struct rt_sigframe __user *sf)
        int err;
 
        err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
-       if (!err)
-               set_current_blocked(&set);
-
-       err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs),
+       err |= __copy_from_user(regs, &(sf->uc.uc_mcontext.regs.scratch),
                                sizeof(sf->uc.uc_mcontext.regs.scratch));
+       if (err)
+               return err;
 
-       return err;
+       set_current_blocked(&set);
+
+       return 0;
 }
 
 static inline int is_do_ss_needed(unsigned int magic)