net: sched: cake: fix null pointer access issue when cake_init() fails

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: net: sched: cake: fix null pointer access issue when cake_init() fails When the default qdisc is cake, if the qdisc of dev_queue fails to be inited during mqprio_init(), cake_reset() is invoked to clear resources. In this case, the tins is NULL, and it will cause gpf issue. The process is as follows: qdisc_create_dflt() cake_init() q->tins = kvcalloc(...) --->failed, q->tins is NULL ... qdisc_put() ... cake_reset() ... cake_dequeue_one() b = &q->tins[...] --->q->tins is NULL The following is the Call Trace information: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] RIP: 0010:cake_dequeue_one+0xc9/0x3c0 Call Trace: <TASK> cake_reset+0xb1/0x140 qdisc_reset+0xed/0x6f0 qdisc_destroy+0x82/0x4c0 qdisc_put+0x9e/0xb0 qdisc_create_dflt+0x2c3/0x4a0 mqprio_init+0xa71/0x1760 qdisc_create+0x3eb/0x1000 tc_modify_qdisc+0x408/0x1720 rtnetlink_rcv_msg+0x38e/0xac0 netlink_rcv_skb+0x12d/0x3a0 netlink_unicast+0x4a2/0x740 netlink_sendmsg+0x826/0xcc0 sock_sendmsg+0xc5/0x100 ____sys_sendmsg+0x583/0x690 ___sys_sendmsg+0xe8/0x160 __sys_sendmsg+0xbf/0x160 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x46/0xb0 RIP: 0033:0x7f89e5122d04 </TASK>

References

• https://git.kernel.org/stable/c/86aa1390898146f1de277bb6d2a8ed7fc7a43f12
• https://git.kernel.org/stable/c/bc8301ea7e7f1bb9d2ba2fcdf7b5ec2f0792b47e
• https://git.kernel.org/stable/c/ae48bee2830bf216800e1447baca39541e27a12e
• https://git.kernel.org/stable/c/154f4c06d9dbec1a14e91286c70b6305810302e0
• https://git.kernel.org/stable/c/1dc0a019550fd38ec6cab2d73c90df2bd659c96b
• https://git.kernel.org/stable/c/51f9a8921ceacd7bf0d3f47fa867a64988ba1dcb