bnxt_en: Mask the bd_cnt field in the TX BD properly

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bnxt_en: Mask the bd_cnt field in the TX BD properly The bd_cnt field in the TX BD specifies the total number of BDs for the TX packet. The bd_cnt field has 5 bits and the maximum number supported is 32 with the value 0. CONFIG_MAX_SKB_FRAGS can be modified and the total number of SKB fragments can approach or exceed the maximum supported by the chip. Add a macro to properly mask the bd_cnt field so that the value 32 will be properly masked and set to 0 in the bd_cnd field. Without this patch, the out-of-range bd_cnt value will corrupt the TX BD and may cause TX timeout. The next patch will check for values exceeding 32.

References

• https://git.kernel.org/stable/c/f60b41b815826f15c4d0323f923f398c423178d0
• https://git.kernel.org/stable/c/107b25db61122d8f990987895c2912927b8b6e3f