[PATCH] cxl: Fix NULL pointer dereference on kernel contexts with no AFU interrupts

* [PATCH] cxl: Fix NULL pointer dereference on kernel contexts with no AFU interrupts
@ 2016-06-29 18:55 Ian Munsie
  2016-06-29 22:28 ` Andrew Donnellan
  2016-07-11 10:19 ` Michael Ellerman
  0 siblings, 2 replies; 6+ messages in thread
From: Ian Munsie @ 2016-06-29 18:55 UTC (permalink / raw)
  To: Michael Ellerman, mikey, linuxppc-dev, Frederic Barrat, Huy Nguyen
  Cc: Ian Munsie

From: Ian Munsie <imunsie@au1.ibm.com>

If a kernel context is initialised and does not have any AFU interrupts
allocated it will cause a NULL pointer dereference when the context is
detached since the irq_names list will not have been initialised.

Move the initialisation of the irq_names list into the cxl_context_init
routine so that it will be valid for the entire lifetime of the context
and will not cause a NULL pointer dereference.

Signed-off-by: Ian Munsie <imunsie@au1.ibm.com>
---
 drivers/misc/cxl/context.c | 2 ++
 drivers/misc/cxl/irq.c     | 3 ---
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 26d206b..edbb99e 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -67,6 +67,8 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master,
 	ctx->pending_fault = false;
 	ctx->pending_afu_err = false;
 
+	INIT_LIST_HEAD(&ctx->irq_names);
+
 	/*
 	 * When we have to destroy all contexts in cxl_context_detach_all() we
 	 * end up with afu_release_irqs() called from inside a
diff --git a/drivers/misc/cxl/irq.c b/drivers/misc/cxl/irq.c
index 8def455..f3a7d4a 100644
--- a/drivers/misc/cxl/irq.c
+++ b/drivers/misc/cxl/irq.c
@@ -260,9 +260,6 @@ int afu_allocate_irqs(struct cxl_context *ctx, u32 count)
 	else
 		alloc_count = count + 1;
 
-	/* Initialize the list head to hold irq names */
-	INIT_LIST_HEAD(&ctx->irq_names);
-
 	if ((rc = cxl_ops->alloc_irq_ranges(&ctx->irqs, ctx->afu->adapter,
 							alloc_count)))
 		return rc;
-- 
2.8.1

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