liquidio: Adjust a NULL pointer handling path in lio_vf_rep_copy_packet

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: liquidio: Adjust a NULL pointer handling path in lio_vf_rep_copy_packet In lio_vf_rep_copy_packet() pg_info->page is compared to a NULL value, but then it is unconditionally passed to skb_add_rx_frag() which looks strange and could lead to null pointer dereference. lio_vf_rep_copy_packet() call trace looks like: octeon_droq_process_packets octeon_droq_fast_process_packets octeon_droq_dispatch_pkt octeon_create_recv_info ...search in the dispatch_list... ->disp_fn(rdisp->rinfo, ...) lio_vf_rep_pkt_recv(struct octeon_recv_info *recv_info, ...) In this path there is no code which sets pg_info->page to NULL. So this check looks unneeded and doesn't solve potential problem. But I guess the author had reason to add a check and I have no such card and can't do real test. In addition, the code in the function liquidio_push_packet() in liquidio/lio_core.c does exactly the same. Based on this, I consider the most acceptable compromise solution to adjust this issue by moving skb_add_rx_frag() into conditional scope. Found by Linux Verification Center (linuxtesting.org) with SVACE.

References

• https://git.kernel.org/stable/c/87d6bdc006f0cbf297a3b2ad6e40ede4c3ee5dc2
• https://git.kernel.org/stable/c/dcc7440f32c7a26b067aff6e7d931ec593024a79
• https://git.kernel.org/stable/c/cbf18d8128a753cb632bef39470d19befd9c7347
• https://git.kernel.org/stable/c/a86490a3712cc513113440a606a0e77130abd47c
• https://git.kernel.org/stable/c/f1ab15a09492a5ae8ab1e2c35ba2cf9e150d25ee
• https://git.kernel.org/stable/c/fd2b613bc4c508e55c1221c6595bb889812a4fea
• https://git.kernel.org/stable/c/a6f4d0ec170a46b5f453cacf55dff5989b42bbfa
• https://git.kernel.org/stable/c/c44711b78608c98a3e6b49ce91678cd0917d5349