From bf018ee644897d7982e1b8dd8b15e97db6e1a4da Mon Sep 17 00:00:00 2001 From: Vasily Gorbik Date: Wed, 27 Nov 2019 18:12:04 +0100 Subject: s390/unwind: filter out unreliable bogus %r14 Currently unwinder unconditionally returns %r14 from the first frame pointed by %r15 from pt_regs. A task could be interrupted when a function already allocated this frame (if it needs it) for its callees or to store local variables. In that case this frame would contain random values from stack or values stored there by a callee. As we are only interested in %r14 to get potential return address, skip bogus return addresses which doesn't belong to kernel text. This helps to avoid duplicating filtering logic in unwider users, most of which use unwind_get_return_address() and would choke on bogus 0 address returned by it otherwise. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- arch/s390/kernel/unwind_bc.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'arch/s390') diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c index e1371cdf9fa5..ef42d5f77ce7 100644 --- a/arch/s390/kernel/unwind_bc.c +++ b/arch/s390/kernel/unwind_bc.c @@ -57,6 +57,11 @@ bool unwind_next_frame(struct unwind_state *state) ip = READ_ONCE_NOCHECK(sf->gprs[8]); reliable = false; regs = NULL; + if (!__kernel_text_address(ip)) { + /* skip bogus %r14 */ + state->regs = NULL; + return unwind_next_frame(state); + } } else { sf = (struct stack_frame *) state->sp; sp = READ_ONCE_NOCHECK(sf->back_chain); -- cgit v1.2.3