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net: ena: ena-com.c: prevent NULL pointer dereference

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comp_ctx can be NULL in a very rare case when an admin command is executed
during the execution of ena_remove().

The bug scenario is as follows:

* ena_destroy_device() sets the comp_ctx to be NULL
* An admin command is executed before executing unregister_netdev(),
  this can still happen because our device can still receive callbacks
  from the netdev infrastructure such as ethtool commands.
* When attempting to access the comp_ctx, the bug occurs since it's set
  to NULL

Fix:
Added a check that comp_ctx is not NULL

Fixes: 1738cd3ed3 ("net: ena: Add a driver for Amazon Elastic Network Adapters (ENA)")
Signed-off-by: Sameeh Jubran <sameehj@amazon.com>
Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Arthur Kiyanovski 2020-02-11 15:17:51 +00:00 committed by David S. Miller
parent 886d208927
commit c207979f5a
1 changed files with 5 additions and 0 deletions
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5
drivers/net/ethernet/amazon/ena/ena_com.c
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@ -200,6 +200,11 @@ static void comp_ctxt_release(struct ena_com_admin_queue *queue,
static struct ena_comp_ctx *get_comp_ctxt(struct ena_com_admin_queue *queue,
u16 command_id, bool capture)
{
if (unlikely(!queue->comp_ctx)) {
pr_err("Completion context is NULL\n");
return NULL;
}
if (unlikely(command_id >= queue->q_depth)) {
pr_err("command id is larger than the queue size. cmd_id: %u queue size %d\n",
command_id, queue->q_depth);