جزئیات آسیب‌پذیری

In the Linux kernel, the following vulnerability has been resolved: virtio-net: fix len check in receive_big() receive_big() bounds the device-announced length by (big_packets_num_skbfrags + 1) * PAGE_SIZE. That is still too loose: add_recvbuf_big() sets sg[1] to start at offset sizeof(struct padded_vnet_hdr) into the first page, so the chain actually carries hdr_len + (PAGE_SIZE - sizeof(padded_vnet_hdr)) + big_packets_num_skbfrags * PAGE_SIZE bytes -- 20 bytes less than the check allows for the common hdr_len == 12 case. A malicious virtio backend can announce a len in that gap. page_to_skb() then walks one frag past the page chain, storing a NULL page->private into skb_shinfo()->frags[MAX_SKB_FRAGS], which is both an out-of-bounds write past the static frag array and a NULL frag handed up the rx path. Bound len by the size add_recvbuf_big() actually advertised.

• https://git.kernel.org/stable/c/f9451d0fd5ba635dcabb49bfe456a6db734a8986
• https://git.kernel.org/stable/c/38e94d63e29f4a5c6eae87ee2c02101aaa321502
• https://git.kernel.org/stable/c/fbeb65154583879d556ea94cb2f15888e9470f3d
• https://git.kernel.org/stable/c/c7fc9adf4e006155f7f2aeda052fbcde25cdcc49
• https://git.kernel.org/stable/c/e6b8463b7d791f3886d7584259d6e9f06a69f12e
• https://git.kernel.org/stable/c/9e5ad06ea826322ce8c58b4a68442a96f600c3c4
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html