36eec020fa
When use the following command to test: 1)ip link add bond0 type bond 2)ip link set bond0 up 3)tc qdisc add dev bond0 root handle ffff: mq 4)tc qdisc replace dev bond0 parent ffff:fff1 handle ffff: mq The kernel reports NULL pointer dereference issue. The stack information is as follows: Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000 Internal error: Oops: 0000000096000006 [#1] SMP Modules linked in: pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : mq_attach+0x44/0xa0 lr : qdisc_graft+0x20c/0x5cc sp : ffff80000e2236a0 x29: ffff80000e2236a0 x28: ffff0000c0e59d80 x27: ffff0000c0be19c0 x26: ffff0000cae3e800 x25: 0000000000000010 x24: 00000000fffffff1 x23: 0000000000000000 x22: ffff0000cae3e800 x21: ffff0000c9df4000 x20: ffff0000c9df4000 x19: 0000000000000000 x18: ffff80000a934000 x17: ffff8000f5b56000 x16: ffff80000bb08000 x15: 0000000000000000 x14: 0000000000000000 x13: 6b6b6b6b6b6b6b6b x12: 6b6b6b6b00000001 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff0000c0be0730 x7 : bbbbbbbbbbbbbbbb x6 : 0000000000000008 x5 : ffff0000cae3e864 x4 : 0000000000000000 x3 : 0000000000000001 x2 : 0000000000000001 x1 : ffff8000090bc23c x0 : 0000000000000000 Call trace: mq_attach+0x44/0xa0 qdisc_graft+0x20c/0x5cc tc_modify_qdisc+0x1c4/0x664 rtnetlink_rcv_msg+0x354/0x440 netlink_rcv_skb+0x64/0x144 rtnetlink_rcv+0x28/0x34 netlink_unicast+0x1e8/0x2a4 netlink_sendmsg+0x308/0x4a0 sock_sendmsg+0x64/0xac ____sys_sendmsg+0x29c/0x358 ___sys_sendmsg+0x90/0xd0 __sys_sendmsg+0x7c/0xd0 __arm64_sys_sendmsg+0x2c/0x38 invoke_syscall+0x54/0x114 el0_svc_common.constprop.1+0x90/0x174 do_el0_svc+0x3c/0xb0 el0_svc+0x24/0xec el0t_64_sync_handler+0x90/0xb4 el0t_64_sync+0x174/0x178 This is because when mq is added for the first time, qdiscs in mq is set to NULL in mq_attach(). Therefore, when replacing mq after adding mq, we need to initialize qdiscs in the mq before continuing to graft. Otherwise, it will couse NULL pointer dereference issue in mq_attach(). And the same issue will occur in the attach functions of mqprio, taprio and htb. ffff:fff1 means that the repalce qdisc is ingress. Ingress does not allow any qdisc to be attached. Therefore, ffff:fff1 is incorrectly used, and the command should be dropped. Fixes: 6ec1c69a8f64 ("net_sched: add classful multiqueue dummy scheduler") Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com> Tested-by: Peilin Ye <peilin.ye@bytedance.com> Acked-by: Jamal Hadi Salim <jhs@mojatatu.com> Link: https://lore.kernel.org/r/20230527093747.3583502-1-shaozhengchao@huawei.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.