CVE-2026-72393: eth: fbnic: don't cache shinfo across skb realloc

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

eth: fbnic: don't cache shinfo across skb realloc

fbnictxlso() calls skbcowhead() which may reallocate the skb including the shared info. We can't use the pointer calculated before the call.

BUG: KASAN: slab-use-after-free in fbnictxlso.isra.0+0x668/0x8e0 Read of size 4 at addr ff110000262edd98 by task swapper/5/0 Call Trace: fbnictxlso.isra.0+0x668/0x8e0 fbnicxmitframe+0x622/0xba0 devhardstartxmit+0xf4/0x620

Allocated by task 8653: allocskb+0x11e/0x5f0 allocskbwithfrags+0xcc/0x6c0 sockallocsendpskb+0x327/0x3f0 ipappenddata+0x188b/0x47a0 ipmakeskb+0x24a/0x300 udpsendmsg+0x14d2/0x21e0

Freed by task 0: kfree+0x123/0x5a0 pskbexpandhead+0x36c/0xfa0 fbnictxlso.isra.0+0x500/0x8e0 fbnicxmitframe+0x622/0xba0 devhardstartxmit+0xf4/0x620 schdirectxmit+0x25b/0x1100

The buggy address belongs to the object at ff110000262edc40 which belongs to the cache skbuffsmallhead of size 640 The buggy address is located 344 bytes inside of freed 640-byte region [ff110000262edc40, ff110000262ede