# CVE-2021-47419: linux: In the Linux kernel, the following vulnerability has been resolved:  net/sched: sch_taprio: properly cancel timer fro...

CVE-2021-47419 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47419, released May 21, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2021-47419
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0023
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: May 21, 2024

## Description

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

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.14.12-1 | [DEBIAN-CVE-2021-47419](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47419.md) | May 21, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.14.12-1 | [DEBIAN-CVE-2021-47419](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47419.md) | May 21, 2024 |
| Linux | linux Debian 14 | 5.14.12-1 | [DEBIAN-CVE-2021-47419](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47419.md) | May 21, 2024 |

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