bnxt_en: Fix memory corruption when FW resources change during ifdown

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bnxt_en: Fix memory corruption when FW resources change during ifdown bnxt_set_dflt_rings() assumes that it is always called before any TC has been created. So it doesn't take bp->num_tc into account and assumes that it is always 0 or 1. In the FW resource or capability change scenario, the FW will return flags in bnxt_hwrm_if_change() that will cause the driver to reinitialize and call bnxt_cancel_reservations(). This will lead to bnxt_init_dflt_ring_mode() calling bnxt_set_dflt_rings() and bp->num_tc may be greater than 1. This will cause bp->tx_ring[] to be sized too small and cause memory corruption in bnxt_alloc_cp_rings(). Fix it by properly scaling the TX rings by bp->num_tc in the code paths mentioned above. Add 2 helper functions to determine bp->tx_nr_rings and bp->tx_nr_rings_per_tc.

References

• https://git.kernel.org/stable/c/d00e98977ef519280b075d783653e2c492fffbb6
• https://git.kernel.org/stable/c/9ab6a9950f152e094395d2e3967f889857daa185
• https://git.kernel.org/stable/c/2747328ba2714f1a7454208dbbc1dc0631990b4a