In the Linux kernel, the following vulnerability has been resolved:
skbuff: Account for tail adjustment during pull operations
Extending the tail can have some unexpected side effects if a program uses a helper like BPFFUNCskbpulldata to read partial content beyond the head skb headlen when all the skbs in the gso fraglist are linear with no headfrag -
kernel BUG at net/core/skbuff.c:4219! pc : skbsegment+0xcf4/0xd2c lr : skbsegment+0x63c/0xd2c Call trace: skbsegment+0xcf4/0xd2c _udpgsosegment+0xa4/0x544 udp4ufofragment+0x184/0x1c0 inetgsosegment+0x16c/0x3a4 skbmacgsosegment+0xd4/0x1b0 _skbgsosegment+0xcc/0x12c udprcvsegment+0x54/0x16c udpqueuercvskb+0x78/0x144 udpunicastrcvskb+0x8c/0xa4 _udp4librcv+0x490/0x68c udprcv+0x20/0x30 ipprotocoldeliverrcu+0x1b0/0x33c iplocaldeliver+0xd8/0x1f0 iprcv+0x98/0x1a4 deliverptypelistskb+0x98/0x1ec _netifreceiveskb_core+0x978/0xc60
Fix this by marking these skbs as GSO_DODGY so segmentation can handle the tail updates accordingly.