net: fix crash when config small gso_max_size/gso_ipv4_max_size

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: fix crash when config small gso_max_size/gso_ipv4_max_size Config a small gso_max_size/gso_ipv4_max_size will lead to an underflow in sk_dst_gso_max_size(), which may trigger a BUG_ON crash, because sk->sk_gso_max_size would be much bigger than device limits. Call Trace: tcp_write_xmit tso_segs = tcp_init_tso_segs(skb, mss_now); tcp_set_skb_tso_segs tcp_skb_pcount_set // skb->len = 524288, mss_now = 8 // u16 tso_segs = 524288/8 = 65535 -> 0 tso_segs = DIV_ROUND_UP(skb->len, mss_now) BUG_ON(!tso_segs) Add check for the minimum value of gso_max_size and gso_ipv4_max_size.

References

• https://git.kernel.org/stable/c/90c8482a5d9791259ba77bfdc1849fc5128b4be7
• https://git.kernel.org/stable/c/e9365368b483328639c03fc730448dccd5a25b6b
• https://git.kernel.org/stable/c/ac5977001eee7660c643f8e07a2de9001990b7b8
• https://git.kernel.org/stable/c/e72fd1389a5364bc6aa6312ecf30bdb5891b9486
• https://git.kernel.org/stable/c/9ab5cf19fb0e4680f95e506d6c544259bf1111c4