[PATCH] [v3] qed: Fix a potential use-after-free in qed_cxt_tables_alloc

[Dinghao Liu]

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: fe56b9e6a8d9 ("qed: Add module with basic common support")
Signed-off-by: Dinghao Liu <dinghao.liu@xxxxxxxxxx>
---

Changelog:

v2: -Change the bug type from double-free to use-after-free.
    -Move the null check against p_mngr->ilt_shadow to the beginning
     of the function qed_ilt_shadow_free().
    -When kcalloc() fails in qed_ilt_shadow_alloc(), just return
     because there is nothing to free.
v3: -Remove refactoring unrelated to bug fixing.
    -Set p_mngr->ilt_shadow to null instead of
     p_hwfn->p_cxt_mngr->ilt_shadow.
---
 drivers/net/ethernet/qlogic/qed/qed_cxt.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/qlogic/qed/qed_cxt.c b/drivers/net/ethernet/qlogic/qed/qed_cxt.c
index 65e20693c549..33f4f58ee51c 100644
--- a/drivers/net/ethernet/qlogic/qed/qed_cxt.c
+++ b/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,
-- 
2.17.1