nvme-pci: add missing condition check for existence of mapped data

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: nvme-pci: add missing condition check for existence of mapped data nvme_map_data() is called when request has physical segments, hence the nvme_unmap_data() should have same condition to avoid dereference.

References

• https://git.kernel.org/stable/c/3f8ec1d6b0ebd8268307d52be8301973fa5a01ec
• https://git.kernel.org/stable/c/be23ae63080e0bf9e246ab20207200bca6585eba
• https://git.kernel.org/stable/c/7cc1f4cd90a00b6191cb8cda2d1302fdce59361c
• https://git.kernel.org/stable/c/d135c3352f7c947a922da93c8e763ee6bc208b64
• https://git.kernel.org/stable/c/77848b379e9f85a08048a2c8b3b4a7e8396f5f83
• https://git.kernel.org/stable/c/70100fe721840bf6d8e5abd25b8bffe4d2e049b7
• https://git.kernel.org/stable/c/c31fad1470389666ac7169fe43aa65bf5b7e2cfd