Commit 2c069a11 authored by Daniel Axtens's avatar Daniel Axtens Committed by Michael Ellerman

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: default avatarDaniel Axtens <dja@axtens.net>
Acked-by: default avatarMichael Neuling <mikey@neuling.org>
Acked-by: default avatarIan Munsie <imunsie@au1.ibm.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent 9958084a
...@@ -73,7 +73,7 @@ static inline void cxl_slbia_core(struct mm_struct *mm) ...@@ -73,7 +73,7 @@ static inline void cxl_slbia_core(struct mm_struct *mm)
spin_lock(&adapter->afu_list_lock); spin_lock(&adapter->afu_list_lock);
for (slice = 0; slice < adapter->slices; slice++) { for (slice = 0; slice < adapter->slices; slice++) {
afu = adapter->afu[slice]; afu = adapter->afu[slice];
if (!afu->enabled) if (!afu || !afu->enabled)
continue; continue;
rcu_read_lock(); rcu_read_lock();
idr_for_each_entry(&afu->contexts_idr, ctx, id) idr_for_each_entry(&afu->contexts_idr, ctx, id)
......
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