On Fri, 2015-07-10 at 09:04 +1000, Daniel Axtens wrote:
> 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
FYI This needs to be (see Documentation/stable_kernel_rules.txt):
Cc: sta...@vger.kernel.org
Other than that, looks good. Thanks.
Acked-by: Michael Neuling <mi...@neuling.org>
> Signed-off-by: Daniel Axtens <d...@axtens.net>
> ---
> 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 11a2044d6b0f..5bcd676bfd59 100644
> --- a/drivers/misc/cxl/main.c
> +++ b/drivers/misc/cxl/main.c
> @@ -86,7 +86,7 @@ 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)
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