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Subject[PATCH 3.12 44/72] arc: don't leak bits of kernel stack into coredump
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From: Al Viro <viro@zeniv.linux.org.uk>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

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: Jiri Slaby <jslaby@suse.cz>
---
arch/arc/kernel/signal.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/arc/kernel/signal.c b/arch/arc/kernel/signal.c
index a0c63fc48457..ca6bcd132a14 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.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)
--
2.10.2
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