# CVE-2021-47014: linux: In the Linux kernel, the following vulnerability has been resolved:  net/sched: act_ct: fix wild memory access when c...

CVE-2021-47014 is fixed in linux on 1 platform, first by DEBIAN-CVE-2021-47014, released February 28, 2024. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2021-47014
- Priority: High
- CVSS: 7.8 (high)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Feb 28, 2024

## Description

In the Linux kernel, the following vulnerability has been resolved:  net/sched: act_ct: fix wild memory access when clearing fragments  while testing re-assembly/re-fragmentation using act_ct, it's possible to observe a crash like the following one:   KASAN: maybe wild-memory-access in range [0x0001000000000448-0x000100000000044f]  CPU: 50 PID: 0 Comm: swapper/50 Tainted: G S                5.12.0-rc7+ #424  Hardware name: Dell Inc. PowerEdge R730/072T6D, BIOS 2.4.3 01/17/2017  RIP: 0010:inet_frag_rbtree_purge+0x50/0xc0  Code: 00 fc ff df 48 89 c3 31 ed 48 89 df e8 a9 7a 38 ff 4c 89 fe 48 89 df 49 89 c6 e8 5b 3a 38 ff 48 8d 7b 40 48 89 f8 48 c1 e8 03 <42> 80 3c 20 00 75 59 48 8d bb d0 00 00 00 4c 8b 6b 40 48 89 f8 48  RSP: 0018:ffff888c31449db8 EFLAGS: 00010203  RAX: 0000200000000089 RBX: 000100000000040e RCX: ffffffff989eb960  RDX: 0000000000000140 RSI: ffffffff97cfb977 RDI: 000100000000044e  RBP: 0000000000000900 R08: 0000000000000000 R09: ffffed1186289350  R10: 0000000000000003 R11: ffffed1186289350 R12: dffffc0000000000  R13: 000100000000040e R14: 0000000000000000 R15: ffff888155e02160  FS:  0000000000000000(0000) GS:ffff888c31440000(0000) knlGS:0000000000000000  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033  CR2: 00005600cb70a5b8 CR3: 0000000a2c014005 CR4: 00000000003706e0  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000  DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400  Call Trace:   <IRQ>   inet_frag_destroy+0xa9/0x150   call_timer_fn+0x2d/0x180   run_timer_softirq+0x4fe/0xe70   __do_softirq+0x197/0x5a0   irq_exit_rcu+0x1de/0x200   sysvec_apic_timer_interrupt+0x6b/0x80   </IRQ>  when act_ct temporarily stores an IP fragment, restoring the skb qdisc cb results in putting random data in FRAG_CB(), and this causes those "wild" memory accesses later, when the rbtree is purged. Never overwrite the skb cb in case tcf_ct_handle_fragments() returns -EINPROGRESS.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 12.15 (bookworm) | 5.14.6-1 | [DEBIAN-CVE-2021-47014](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47014.md) | Feb 28, 2024 |
| Linux | linux Debian 13.5 (trixie) | 5.14.6-1 | [DEBIAN-CVE-2021-47014](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47014.md) | Feb 28, 2024 |
| Linux | linux Debian 14 | 5.14.6-1 | [DEBIAN-CVE-2021-47014](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47014.md) | Feb 28, 2024 |

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