From e461a9816a1ac5b4aeb61621b817225b61e46a68 Mon Sep 17 00:00:00 2001 From: Zhou Qingyang Date: Wed, 1 Dec 2021 00:44:38 +0800 Subject: [PATCH] net/mlx4_en: Fix an use-after-free bug in mlx4_en_try_alloc_resources() commit addad7643142f500080417dd7272f49b7a185570 upstream. In mlx4_en_try_alloc_resources(), mlx4_en_copy_priv() is called and tmp->tx_cq will be freed on the error path of mlx4_en_copy_priv(). After that mlx4_en_alloc_resources() is called and there is a dereference of &tmp->tx_cq[t][i] in mlx4_en_alloc_resources(), which could lead to a use after free problem on failure of mlx4_en_copy_priv(). Fix this bug by adding a check of mlx4_en_copy_priv() This bug was found by a static analyzer. The analysis employs differential checking to identify inconsistent security operations (e.g., checks or kfrees) between two code paths and confirms that the inconsistent operations are not recovered in the current function or the callers, so they constitute bugs. Note that, as a bug found by static analysis, it can be a false positive or hard to trigger. Multiple researchers have cross-reviewed the bug. Builds with CONFIG_MLX4_EN=m show no new warnings, and our static analyzer no longer warns about this code. Fixes: ec25bc04ed8e ("net/mlx4_en: Add resilience in low memory systems") Signed-off-by: Zhou Qingyang Reviewed-by: Leon Romanovsky Link: https://lore.kernel.org/r/20211130164438.190591-1-zhou1615@umn.edu Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/mellanox/mlx4/en_netdev.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c index d029179a4804..91334229c120 100644 --- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c +++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c @@ -2281,9 +2281,14 @@ int mlx4_en_try_alloc_resources(struct mlx4_en_priv *priv, bool carry_xdp_prog) { struct bpf_prog *xdp_prog; - int i, t; + int i, t, ret; - mlx4_en_copy_priv(tmp, priv, prof); + ret = mlx4_en_copy_priv(tmp, priv, prof); + if (ret) { + en_warn(priv, "%s: mlx4_en_copy_priv() failed, return\n", + __func__); + return ret; + } if (mlx4_en_alloc_resources(tmp)) { en_warn(priv,