CVE-2021-47419

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net/sched: sch_taprio: properly cancel timer from taprio_destroy()<br /> <br /> There is a comment in qdisc_create() about us not calling ops-&gt;reset()<br /> in some cases.<br /> <br /> err_out4:<br /> /*<br /> * Any broken qdiscs that would require a ops-&gt;reset() here?<br /> * The qdisc was never in action so it shouldn&amp;#39;t be necessary.<br /> */<br /> <br /> As taprio sets a timer before actually receiving a packet, we need<br /> to cancel it from ops-&gt;destroy, just in case ops-&gt;reset has not<br /> been called.<br /> <br /> syzbot reported:<br /> <br /> ODEBUG: free active (active state 0) object type: hrtimer hint: advance_sched+0x0/0x9a0 arch/x86/include/asm/atomic64_64.h:22<br /> WARNING: CPU: 0 PID: 8441 at lib/debugobjects.c:505 debug_print_object+0x16e/0x250 lib/debugobjects.c:505<br /> Modules linked in:<br /> CPU: 0 PID: 8441 Comm: syz-executor813 Not tainted 5.14.0-rc6-syzkaller #0<br /> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011<br /> RIP: 0010:debug_print_object+0x16e/0x250 lib/debugobjects.c:505<br /> Code: ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 af 00 00 00 48 8b 14 dd e0 d3 e3 89 4c 89 ee 48 c7 c7 e0 c7 e3 89 e8 5b 86 11 05 0b 83 05 85 03 92 09 01 48 83 c4 18 5b 5d 41 5c 41 5d 41 5e c3<br /> RSP: 0018:ffffc9000130f330 EFLAGS: 00010282<br /> RAX: 0000000000000000 RBX: 0000000000000003 RCX: 0000000000000000<br /> RDX: ffff88802baeb880 RSI: ffffffff815d87b5 RDI: fffff52000261e58<br /> RBP: 0000000000000001 R08: 0000000000000000 R09: 0000000000000000<br /> R10: ffffffff815d25ee R11: 0000000000000000 R12: ffffffff898dd020<br /> R13: ffffffff89e3ce20 R14: ffffffff81653630 R15: dffffc0000000000<br /> FS: 0000000000f0d300(0000) GS:ffff8880b9d00000(0000) knlGS:0000000000000000<br /> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033<br /> CR2: 00007ffb64b3e000 CR3: 0000000036557000 CR4: 00000000001506e0<br /> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000<br /> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400<br /> Call Trace:<br /> __debug_check_no_obj_freed lib/debugobjects.c:987 [inline]<br /> debug_check_no_obj_freed+0x301/0x420 lib/debugobjects.c:1018<br /> slab_free_hook mm/slub.c:1603 [inline]<br /> slab_free_freelist_hook+0x171/0x240 mm/slub.c:1653<br /> slab_free mm/slub.c:3213 [inline]<br /> kfree+0xe4/0x540 mm/slub.c:4267<br /> qdisc_create+0xbcf/0x1320 net/sched/sch_api.c:1299<br /> tc_modify_qdisc+0x4c8/0x1a60 net/sched/sch_api.c:1663<br /> rtnetlink_rcv_msg+0x413/0xb80 net/core/rtnetlink.c:5571<br /> netlink_rcv_skb+0x153/0x420 net/netlink/af_netlink.c:2504<br /> netlink_unicast_kernel net/netlink/af_netlink.c:1314 [inline]<br /> netlink_unicast+0x533/0x7d0 net/netlink/af_netlink.c:1340<br /> netlink_sendmsg+0x86d/0xdb0 net/netlink/af_netlink.c:1929<br /> sock_sendmsg_nosec net/socket.c:704 [inline]<br /> sock_sendmsg+0xcf/0x120 net/socket.c:724<br /> ____sys_sendmsg+0x6e8/0x810 net/socket.c:2403<br /> ___sys_sendmsg+0xf3/0x170 net/socket.c:2457<br /> __sys_sendmsg+0xe5/0x1b0 net/socket.c:2486<br /> do_syscall_x64 arch/x86/entry/common.c:50 [inline]<br /> do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80