[PATCH v4 1/2] s390/unwind: add stack pointer alignment sanity checks

[Vasily Gorbik]

From: Miroslav Benes <mbenes@xxxxxxx>

ABI requires SP to be aligned 8 bytes, report unwinding error otherwise.

Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
---
 arch/s390/kernel/dumpstack.c | 4 ++++
 arch/s390/kernel/unwind_bc.c | 4 ++++
 2 files changed, 8 insertions(+)

diff --git a/arch/s390/kernel/dumpstack.c b/arch/s390/kernel/dumpstack.c
index d74e21a23703..d306fe04489a 100644
--- a/arch/s390/kernel/dumpstack.c
+++ b/arch/s390/kernel/dumpstack.c
@@ -94,6 +94,10 @@ int get_stack_info(unsigned long sp, struct task_struct *task,
 	if (!sp)
 		goto unknown;
 
+	/* Sanity check: ABI requires SP to be aligned 8 bytes. */
+	if (sp & 0x7)
+		goto unknown;
+
 	/* Check per-task stack */
 	if (in_task_stack(sp, task, info))
 		goto recursion_check;
diff --git a/arch/s390/kernel/unwind_bc.c b/arch/s390/kernel/unwind_bc.c
index ef42d5f77ce7..da2d4d4c5b0e 100644
--- a/arch/s390/kernel/unwind_bc.c
+++ b/arch/s390/kernel/unwind_bc.c
@@ -92,6 +92,10 @@ bool unwind_next_frame(struct unwind_state *state)
 		}
 	}
 
+	/* Sanity check: ABI requires SP to be aligned 8 bytes. */
+	if (sp & 0x7)
+		goto out_err;
+
 	ip = ftrace_graph_ret_addr(state->task, &state->graph_idx, ip, (void *) sp);
 
 	/* Update unwind state */
-- 
2.21.0