qed: Fix a potential use-after-free in qed_cxt_tables_alloc

qed_ilt_shadow_alloc() will call qed_ilt_shadow_free() to
free p_hwfn->p_cxt_mngr->ilt_shadow on error. However,
qed_cxt_tables_alloc() accesses the freed pointer on failure
of qed_ilt_shadow_alloc() through calling qed_cxt_mngr_free(),
which may lead to use-after-free. Fix this issue by setting
p_mngr->ilt_shadow to NULL in qed_ilt_shadow_free().

Fixes: fe56b9e6 ("qed: Add module with basic common support")
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Signed-off-by: Dinghao Liu <dinghao.liu@zju.edu.cn>
Link: https://lore.kernel.org/r/20231210045255.21383-1-dinghao.liu@zju.edu.cnSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/qlogic/qed/qed_cxt.c

@@ -933,6 +933,7 @@ static void qed_ilt_shadow_free(struct qed_hwfn *p_hwfn)
 		p_dma->virt_addr = NULL;
 	}
 	kfree(p_mngr->ilt_shadow);
+	p_mngr->ilt_shadow = NULL;
 }
 
 static int qed_ilt_blk_alloc(struct qed_hwfn *p_hwfn,