CVE-2025-68742

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix invalid prog->stats access when updateeffectiveprogs fails

Syzkaller triggers an invalid memory access issue following fault injection in updateeffectiveprogs. The issue can be described as follows:

_cgroupbpfdetach updateeffectiveprogs computeeffectiveprogs bpfprogarrayalloc <-- fault inject purgeeffectiveprogs /* change to dummybpfprog */ array->items[index] = &dummybpfprog.prog

---softirq start--- __do_softirq ... __cgroupbpfrunfilterskb __bpfprogrunsavecb bpfprogrun stats = thiscpuptr(prog->stats) /* invalid memory access */ flags = u64statsupdatebeginirqsave(&stats->syncp) ---softirq end---

staticbranchdec(&cgroupbpfenabled_key[atype])

The reason is that fault injection caused updateeffectiveprogs to fail and then changed the original prog into dummybpfprog.prog in purgeeffectiveprogs. Then a softirq came, and accessing the members of dummybpfprog.prog in the softirq triggers invalid mem access.

To fix it, skip updating stats when stats is NULL.