CVE-2021-47438

In the Linux kernel, the following vulnerability has been resolved:

net/mlx5e: Fix memory leak in mlx5_core_destroy_cq() error path

Prior to this patch in case mlx5_core_destroy_cq() failed it returns without completing all destroy operations and that leads to memory leak. Instead, complete the destroy flow before return error.

Also move mlx5_debug_cq_remove() to the beginning of mlx5_core_destroy_cq() to be symmetrical with mlx5_core_create_cq().

kmemleak complains on:

unreferenced object 0xc000000038625100 (size 64): comm ethtool, pid 28301, jiffies 4298062946 (age 785.380s) hex dump (first 32 bytes): 60 01 48 94 00 00 00 c0 b8 05 34 c3 00 00 00 c0 `.H…….4….. 02 00 00 00 00 00 00 00 00 db 7d c1 00 00 00 c0 ……….}….. backtrace: [<000000009e8643cb>] add_res_tree+0xd0/0x270 [mlx5_core] [<00000000e7cb8e6c>] mlx5_debug_cq_add+0x5c/0xc0 [mlx5_core] [<000000002a12918f>] mlx5_core_create_cq+0x1d0/0x2d0 [mlx5_core] [<00000000cef0a696>] mlx5e_create_cq+0x210/0x3f0 [mlx5_core] [<000000009c642c26>] mlx5e_open_cq+0xb4/0x130 [mlx5_core] [<0000000058dfa578>] mlx5e_ptp_open+0x7f4/0xe10 [mlx5_core] [<0000000081839561>] mlx5e_open_channels+0x9cc/0x13e0 [mlx5_core] [<0000000009cf05d4>] mlx5e_switch_priv_channels+0xa4/0x230 [mlx5_core] [<0000000042bbedd8>] mlx5e_safe_switch_params+0x14c/0x300 [mlx5_core] [<0000000004bc9db8>] set_pflag_tx_port_ts+0x9c/0x160 [mlx5_core] [<00000000a0553443>] mlx5e_set_priv_flags+0xd0/0x1b0 [mlx5_core] [<00000000a8f3d84b>] ethnl_set_privflags+0x234/0x2d0 [<00000000fd27f27c>] genl_family_rcv_msg_doit+0x108/0x1d0 [<00000000f495e2bb>] genl_family_rcv_msg+0xe4/0x1f0 [<00000000646c5c2c>] genl_rcv_msg+0x78/0x120 [<00000000d53e384e>] netlink_rcv_skb+0x74/0x1a0

Weakness

The product does not sufficiently track and release allocated memory after it has been used, making the memory unavailable for reallocation and reuse.

Affected Software

Potential Mitigations

• Choose a language or tool that provides automatic memory management, or makes manual memory management less error-prone.
• For example, glibc in Linux provides protection against free of invalid pointers.
• When using Xcode to target OS X or iOS, enable automatic reference counting (ARC) [REF-391].
• To help correctly and consistently manage memory when programming in C++, consider using a smart pointer class such as std::auto_ptr (defined by ISO/IEC ISO/IEC 14882:2003), std::shared_ptr and std::unique_ptr (specified by an upcoming revision of the C++ standard, informally referred to as C++ 1x), or equivalent solutions such as Boost.

References

• https://git.kernel.org/stable/c/4f7bddf8c5c01cac74373443b13a68e1c6723a94
• https://git.kernel.org/stable/c/94b960b9deffc02fc0747afc01f72cc62ab099e3
• https://git.kernel.org/stable/c/ed8aafea4fec9c654e63445236e0b505e27ed3a7
• https://git.kernel.org/stable/c/4f7bddf8c5c01cac74373443b13a68e1c6723a94
• https://git.kernel.org/stable/c/94b960b9deffc02fc0747afc01f72cc62ab099e3
• https://git.kernel.org/stable/c/ed8aafea4fec9c654e63445236e0b505e27ed3a7