Patch "arc: don't leak bits of kernel stack into coredump" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

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

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
arc-don-t-leak-bits-of-kernel-stack-into-coredump.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Al Viro <[email protected]>
Date: Sat, 10 Sep 2016 16:31:04 -0400
Subject: arc: don't leak bits of kernel stack into coredump

From: Al Viro <[email protected]>

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...

---
 arch/arc/kernel/signal.c |    8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

@@ -107,13 +107,13 @@ static int restore_usr_regs(struct pt_re
 	struct user_regs_struct uregs;
 
 	err = __copy_from_user(&set, &sf->uc.uc_sigmask, sizeof(set));
-	if (!err)
-		set_current_blocked(&set);
-
 	err |= __copy_from_user(&uregs.scratch,
 				&(sf->uc.uc_mcontext.regs.scratch),
 				sizeof(sf->uc.uc_mcontext.regs.scratch));
+	if (err)
+		return err;
 
+	set_current_blocked(&set);
 	regs->bta	= uregs.scratch.bta;
 	regs->lp_start	= uregs.scratch.lp_start;
 	regs->lp_end	= uregs.scratch.lp_end;

@@ -138,7 +138,7 @@ static int restore_usr_regs(struct pt_re
 	regs->r0	= uregs.scratch.r0;
 	regs->sp	= uregs.scratch.sp;
 
-	return err;
+	return 0;
 }
 
 static inline int is_do_ss_needed(unsigned int magic)

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/fs-super.c-fix-race-between-freeze_super-and-thaw_super.patch queue-4.4/arc-don-t-leak-bits-of-kernel-stack-into-coredump.patch