AZL-97140

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

net/ncsi: fix heap OOB read in NCSICMDSEND_CMD payload length

ncsisendcmdnl() takes the number of bytes to copy from the attacker-controlled ncsipkthdr.length field of the in-band packet header, while the source buffer is the NCSIATTRDATA netlink attribute whose readable size is nlalen() - sizeof(ncsipkthdr). The two length sources are never cross-checked: only nlalen() >= sizeof(struct ncsipkt_hdr) is enforced.

With hdr->length set larger than the attribute payload (up to 65535 against at most 2032 readable bytes), ncsicmdhandleroem() copies past the end of the netlink attribute buffer with unsafememcpy(), leaking up to ~64KB of kernel heap memory into the transmitted NCSI command packet. The destination skb is sized by the declared payload, so the write side does not overflow - this is a pure OOB read / information leak, reachable with CAPNETADMIN on systems with a registered NCSI device (e.g. OpenBMC on Aspeed BMC SoCs, where NET_NCSI=y is standard).

Reject commands whose declared payload extends past the end of the data attribute.

The issue was found by the autokbug dynamic kernel fuzzer at Tencent Yunding Lab.