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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id g14sm11222856pgo.88.2021.12.13.14.33.36 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 13 Dec 2021 14:33:36 -0800 (PST) From: Kees Cook To: linux-hardening@vger.kernel.org Cc: Kees Cook , Saeed Mahameed , Leon Romanovsky , "David S. Miller" , Jakub Kicinski , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 02/17] net/mlx5e: Avoid field-overflowing memcpy() Date: Mon, 13 Dec 2021 14:33:16 -0800 Message-Id: <20211213223331.135412-3-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20211213223331.135412-1-keescook@chromium.org> References: <20211213223331.135412-1-keescook@chromium.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=5948; h=from:subject; bh=EppcbcSPKk/Rd6MsdVLuv/qMCS6eKKFQ506lkSpOmRU=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBht8o3POvClLvKHN/lynYrq7OpZm6VGeDuqqGw1AJE Ty8tY7KJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYbfKNwAKCRCJcvTf3G3AJtaMD/ 0R0sbrtwDATl2p4FnXCY0lXP3LfdvTHLLPHMDy9Nq7ZlgTZTwzQqUVm0LjNfkF+fbSbdcAMhSlr8rV qvqaLdvRPNFtz2D6GohM/GfKfoZ1UjJNiOvgfbJ0ilYRRRG4anuYYl1gMfZ3Ko6QO1EtU3Y1qU8YIa xB5f2mXDTs6OZHvPIDSqbTlxjeVSn5fJjvjtabbElOkFTLszEQ0UQnA0PBAS2UiOWbuthNCuaEt16N vA8qms5FddqfDqm5c9FAKCkAu8eNkspw7nIIiGoY5PqxV1TrhSUrnrsbrVvtTFFmOGxrTLGUdyHq0Q kFEJEgcTU72q9mnFGzW8TByHYgbW/8fYRA/kPyQVBpzI8m86xwBkTw4DNGmAhZcDV8veSnziKAJl8k HyC0qNQQYpe38vZ3NzMc7JGRX3fXdbgk449asLBRJE7Azx6MN89EkyuZBTJIQxL7tXBBWVTTWe/9su 6eT0b5aESPNrhJMR8xcGgkRFLbr6qI8oXVKS/06GOasghrwozIwW/jojcsEtdmB/RiWPRkXGNvez2j bt2cNM+2zXmFhtf0XPQJmUrYulpa0tiq5LQIvf0koDFyKxZ0JaA56ZdGBXzrQY9JMqXd1ueG6nE3Gh MimlG1ooMCxRn0fxoY4Nma91cdEOpRa+XeYuM9BQ7dGs8BEwVL4o7u8wFibw== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid intentionally writing across neighboring fields. Use flexible arrays instead of zero-element arrays (which look like they are always overflowing) and split the cross-field memcpy() into two halves that can be appropriately bounds-checked by the compiler. We were doing: #define ETH_HLEN 14 #define VLAN_HLEN 4 ... #define MLX5E_XDP_MIN_INLINE (ETH_HLEN + VLAN_HLEN) ... struct mlx5e_tx_wqe *wqe = mlx5_wq_cyc_get_wqe(wq, pi); ... struct mlx5_wqe_eth_seg *eseg = &wqe->eth; struct mlx5_wqe_data_seg *dseg = wqe->data; ... memcpy(eseg->inline_hdr.start, xdptxd->data, MLX5E_XDP_MIN_INLINE); target is wqe->eth.inline_hdr.start (which the compiler sees as being 2 bytes in size), but copying 18, intending to write across start (really vlan_tci, 2 bytes). The remaining 16 bytes get written into wqe->data[0], covering byte_count (4 bytes), lkey (4 bytes), and addr (8 bytes). struct mlx5e_tx_wqe { struct mlx5_wqe_ctrl_seg ctrl; /* 0 16 */ struct mlx5_wqe_eth_seg eth; /* 16 16 */ struct mlx5_wqe_data_seg data[]; /* 32 0 */ /* size: 32, cachelines: 1, members: 3 */ /* last cacheline: 32 bytes */ }; struct mlx5_wqe_eth_seg { u8 swp_outer_l4_offset; /* 0 1 */ u8 swp_outer_l3_offset; /* 1 1 */ u8 swp_inner_l4_offset; /* 2 1 */ u8 swp_inner_l3_offset; /* 3 1 */ u8 cs_flags; /* 4 1 */ u8 swp_flags; /* 5 1 */ __be16 mss; /* 6 2 */ __be32 flow_table_metadata; /* 8 4 */ union { struct { __be16 sz; /* 12 2 */ u8 start[2]; /* 14 2 */ } inline_hdr; /* 12 4 */ struct { __be16 type; /* 12 2 */ __be16 vlan_tci; /* 14 2 */ } insert; /* 12 4 */ __be32 trailer; /* 12 4 */ }; /* 12 4 */ /* size: 16, cachelines: 1, members: 9 */ /* last cacheline: 16 bytes */ }; struct mlx5_wqe_data_seg { __be32 byte_count; /* 0 4 */ __be32 lkey; /* 4 4 */ __be64 addr; /* 8 8 */ /* size: 16, cachelines: 1, members: 3 */ /* last cacheline: 16 bytes */ }; So, split the memcpy() so the compiler can reason about the buffer sizes. "pahole" shows no size nor member offset changes to struct mlx5e_tx_wqe nor struct mlx5e_umr_wqe. "objdump -d" shows no meaningful object code changes (i.e. only source line number induced differences and optimizations). Cc: Saeed Mahameed Cc: Leon Romanovsky Cc: "David S. Miller" Cc: Jakub Kicinski Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: Jesper Dangaard Brouer Cc: John Fastabend Cc: netdev@vger.kernel.org Cc: linux-rdma@vger.kernel.org Cc: bpf@vger.kernel.org Signed-off-by: Kees Cook --- drivers/net/ethernet/mellanox/mlx5/core/en.h | 6 +++--- drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c | 4 +++- 2 files changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h index e77c4159713f..5d8e0a712313 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en.h +++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h @@ -225,7 +225,7 @@ static inline int mlx5e_get_max_num_channels(struct mlx5_core_dev *mdev) struct mlx5e_tx_wqe { struct mlx5_wqe_ctrl_seg ctrl; struct mlx5_wqe_eth_seg eth; - struct mlx5_wqe_data_seg data[0]; + struct mlx5_wqe_data_seg data[]; }; struct mlx5e_rx_wqe_ll { @@ -242,8 +242,8 @@ struct mlx5e_umr_wqe { struct mlx5_wqe_umr_ctrl_seg uctrl; struct mlx5_mkey_seg mkc; union { - struct mlx5_mtt inline_mtts[0]; - struct mlx5_klm inline_klms[0]; + DECLARE_FLEX_ARRAY(struct mlx5_mtt, inline_mtts); + DECLARE_FLEX_ARRAY(struct mlx5_klm, inline_klms); }; }; diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c index 2f0df5cc1a2d..efae2444c26f 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en/xdp.c @@ -341,8 +341,10 @@ mlx5e_xmit_xdp_frame(struct mlx5e_xdpsq *sq, struct mlx5e_xmit_data *xdptxd, /* copy the inline part if required */ if (sq->min_inline_mode != MLX5_INLINE_MODE_NONE) { - memcpy(eseg->inline_hdr.start, xdptxd->data, MLX5E_XDP_MIN_INLINE); + memcpy(eseg->inline_hdr.start, xdptxd->data, sizeof(eseg->inline_hdr.start)); eseg->inline_hdr.sz = cpu_to_be16(MLX5E_XDP_MIN_INLINE); + memcpy(dseg, xdptxd->data + sizeof(eseg->inline_hdr.start), + MLX5E_XDP_MIN_INLINE - sizeof(eseg->inline_hdr.start)); dma_len -= MLX5E_XDP_MIN_INLINE; dma_addr += MLX5E_XDP_MIN_INLINE; dseg++;