cxl/features: Add check for no entries in cxl_feature_info

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: cxl/features: Add check for no entries in cxl_feature_info cxl EDAC calls cxl_feature_info() to get the feature information and if the hardware has no Features support, cxlfs may be passed in as NULL. [ 51.957498] BUG: kernel NULL pointer dereference, address: 0000000000000008 [ 51.965571] #PF: supervisor read access in kernel mode [ 51.971559] #PF: error_code(0x0000) - not-present page [ 51.977542] PGD 17e4f6067 P4D 0 [ 51.981384] Oops: Oops: 0000 [#1] SMP NOPTI [ 51.986300] CPU: 49 UID: 0 PID: 3782 Comm: systemd-udevd Not tainted 6.17.0dj test+ #64 PREEMPT(voluntary) [ 51.997355] Hardware name: <removed> [ 52.009790] RIP: 0010:cxl_feature_info+0xa/0x80 [cxl_core] Add a check for cxlfs before dereferencing it and return -EOPNOTSUPP if there is no cxlfs created due to no hardware support.

References

• https://git.kernel.org/stable/c/b8a69e3b1a460bf5d96dd53cbd121aa2cd346886
• https://git.kernel.org/stable/c/a375246fcf2bbdaeb1df7fa7ee5a8b884a89085e