From 2c069a118fe1d80c47dca84e1561045fc7f3cc9e Mon Sep 17 00:00:00 2001 From: Daniel Axtens Date: Fri, 10 Jul 2015 09:04:25 +1000 Subject: [PATCH] cxl: Check if afu is not null in cxl_slbia The pointer to an AFU in the adapter's list of AFUs can be null if we're in the process of removing AFUs. The afu_list_lock doesn't guard against this. Say we have 2 slices, and we're in the process of removing cxl. - We remove the AFUs in order (see cxl_remove). In cxl_remove_afu for AFU 0, we take the lock, set adapter->afu[0] = NULL, and release the lock. - Then we get an slbia. In cxl_slbia we take the lock, and set afu = adapter->afu[0], which is NULL. - Therefore our attempt to check afu->enabled will blow up. Therefore, check if afu is a null pointer before dereferencing it. Cc: stable@vger.kernel.org Signed-off-by: Daniel Axtens Acked-by: Michael Neuling Acked-by: Ian Munsie Signed-off-by: Michael Ellerman --- drivers/misc/cxl/main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c index 833348e2c9cb..4a164ab8b35a 100644 --- a/drivers/misc/cxl/main.c +++ b/drivers/misc/cxl/main.c @@ -73,7 +73,7 @@ static inline void cxl_slbia_core(struct mm_struct *mm) spin_lock(&adapter->afu_list_lock); for (slice = 0; slice < adapter->slices; slice++) { afu = adapter->afu[slice]; - if (!afu->enabled) + if (!afu || !afu->enabled) continue; rcu_read_lock(); idr_for_each_entry(&afu->contexts_idr, ctx, id) -- 2.11.0