wifi: mac80211: Set n_channels after allocating struct cfg80211_scan_request

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: Set n_channels after allocating struct cfg80211_scan_request Make sure that n_channels is set after allocating the struct cfg80211_registered_device::int_scan_req member. Seen with syzkaller: UBSAN: array-index-out-of-bounds in net/mac80211/scan.c:1208:5 index 0 is out of range for type 'struct ieee80211_channel *[] __counted_by(n_channels)' (aka 'struct ieee80211_channel *[]') This was missed in the initial conversions because I failed to locate the allocation likely due to the "sizeof(void *)" not matching the "channels" array type.

References

• https://git.kernel.org/stable/c/fde33ab3c052a302ee8a0b739094b88ceae4dd67
• https://git.kernel.org/stable/c/07c737d9ab02c07b562aefcca16aa95077368e24
• https://git.kernel.org/stable/c/e3192e999a0d05ea0ba2c59c09afaf0b8ee70b81
• https://git.kernel.org/stable/c/82bbe02b2500ef0a62053fe2eb84773fe31c5a0a