CVE-2024-26815: Out-of-bounds Write

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

net/sched: taprio: proper TCA_TAPRIO_TC_ENTRY_INDEX check

taprio_parse_tc_entry() is not correctly checking TCA_TAPRIO_TC_ENTRY_INDEX attribute:

int tc; // Signed value

tc = nla_get_u32(tb[TCA_TAPRIO_TC_ENTRY_INDEX]); if (tc >= TC_QOPT_MAX_QUEUE) { NL_SET_ERR_MSG_MOD(extack, "TC entry index out of range"); return -ERANGE; }

syzbot reported that it could fed arbitary negative values:

UBSAN: shift-out-of-bounds in net/sched/sch_taprio.c:1722:18 shift exponent -2147418108 is negative CPU: 0 PID: 5066 Comm: syz-executor367 Not tainted 6.8.0-rc7-syzkaller-00136-gc8a5c731fd12 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/29/2024 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106 ubsan_epilogue lib/ubsan.c:217 [inline] __ubsan_handle_shift_out_of_bounds+0x3c7/0x420 lib/ubsan.c:386 taprio_parse_tc_entry net/sched/sch_taprio.c:1722 [inline] taprio_parse_tc_entries net/sched/sch_taprio.c:1768 [inline] taprio_change+0xb87/0x57d0 net/sched/sch_taprio.c:1877 taprio_init+0x9da/0xc80 net/sched/sch_taprio.c:2134 qdisc_create+0x9d4/0x1190 net/sched/sch_api.c:1355 tc_modify_qdisc+0xa26/0x1e40 net/sched/sch_api.c:1776 rtnetlink_rcv_msg+0x885/0x1040 net/core/rtnetlink.c:6617 netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2543 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline] netlink_unicast+0x7ea/0x980 net/netlink/af_netlink.c:1367 netlink_sendmsg+0xa3b/0xd70 net/netlink/af_netlink.c:1908 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0x221/0x270 net/socket.c:745 ____sys_sendmsg+0x525/0x7d0 net/socket.c:2584 ___sys_sendmsg net/socket.c:2638 [inline] __sys_sendmsg+0x2b0/0x3a0 net/socket.c:2667 do_syscall_64+0xf9/0x240 entry_SYSCALL_64_after_hwframe+0x6f/0x77 RIP: 0033:0x7f1b2dea3759 Code: 48 83 c4 28 c3 e8 d7 19 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd4de452f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 00007f1b2def0390 RCX: 00007f1b2dea3759 RDX: 0000000000000000 RSI: 00000000200007c0 RDI: 0000000000000004 RBP: 0000000000000003 R08: 0000555500000000 R09: 0000555500000000 R10: 0000555500000000 R11: 0000000000000246 R12: 00007ffd4de45340 R13: 00007ffd4de45310 R14: 0000000000000001 R15: 00007ffd4de45340