Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Add bpf_prog_run_data_pointers() syzbot found that cls_bpf_classify() is able to change tc_skb_cb(skb)->drop_reason triggering a warning in sk_skb_reason_drop(). WARNING: CPU: 0 PID: 5965 at net/core/skbuff.c:1192 __sk_skb_reason_drop net/core/skbuff.c:1189 [inline] WARNING: CPU: 0 PID: 5965 at net/core/skbuff.c:1192 sk_skb_reason_drop+0x76/0x170 net/core/skbuff.c:1214 struct tc_skb_cb has been added in commit ec624fe740b4 ("net/sched: Extend qdisc control block with tc control block"), which added a wrong interaction with db58ba459202 ("bpf: wire in data and data_end for cls_act_bpf"). drop_reason was added later. Add bpf_prog_run_data_pointers() helper to save/restore the net_sched storage colliding with BPF data_meta/data_end.

References 6

• git.kernel.org https://git.kernel.org/stable/c/4ef92743625818932b9c320152b58274c05e5053
• git.kernel.org https://git.kernel.org/stable/c/5e149d8a8e732126fb6014efd60075cf63a73f91
• git.kernel.org https://git.kernel.org/stable/c/6392e5f4b1a3cce10e828309baf35d22abd3457d
• git.kernel.org https://git.kernel.org/stable/c/8dd2fe5f5d586c8e87307b7a271f6b994afcc006
• git.kernel.org https://git.kernel.org/stable/c/baa61dcaa50b7141048c8d2aede7fe9ed8f21d11
• git.kernel.org https://git.kernel.org/stable/c/c4cdd143c35974a2cedd000fa9eb3accc3023b20

Remediation