sched: address a potential NULL pointer dereference in the GRED scheduler.

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: sched: address a potential NULL pointer dereference in the GRED scheduler. If kzalloc in gred_init returns a NULL pointer, the code follows the error handling path, invoking gred_destroy. This, in turn, calls gred_offload, where memset could receive a NULL pointer as input, potentially leading to a kernel crash. When table->opt is NULL in gred_init(), gred_change_table_def() is not called yet, so it is not necessary to call ->ndo_setup_tc() in gred_offload().

References

• https://git.kernel.org/stable/c/d02c9acd68950a444acda18d514e2b41f846cb7f
• https://git.kernel.org/stable/c/0f0a152957d64ce45b4c27c687e7d087e8f45079
• https://git.kernel.org/stable/c/68896dd50180b38ea552e49a6a00b685321e5769
• https://git.kernel.org/stable/c/5f996b4f80c2cef1f9c77275055e7fcba44c9199
• https://git.kernel.org/stable/c/115ef44a98220fddfab37a39a19370497cd718b9