[PATCH 3.10 102/319] arc: don't leak bits of kernel stack into coredump

Willy Tarreau
2017-02-05T19:31:06Z

From: Al Viro <viro@zeniv.linux.org.uk>

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>
---
arch/arc/kernel/signal.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index 6763654..0823087 100644
--- 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)
--
2.8.0.rc2.1.gbe9624a