In the Linux kernel, the following vulnerability has been resolved: net: fix use-after-free in tw_timer_handler A real world panic issue was found as follow in Linux 5.4. BUG: unable to handle page fault for address: ffffde49a863de28 PGD 7e6fe62067 P4D 7e6fe62067 PUD 7e6fe63067 PMD f51e064067 PTE 0 RIP: 0010:tw_timer_handler+0x20/0x40 Call Trace: call_timer_fn+0x2b/0x120 run_timer_softirq+0x1ef/0x450 __do_softirq+0x10d/0x2b8 irq_exit+0xc7/0xd0 smp_apic_timer_interrupt+0x68/0x120 apic_timer_interrupt+0xf/0x20 This issue was also reported since 2017 in the thread [1], unfortunately, the issue was still can be reproduced after fixing DCCP. The ipv4_mib_exit_net is called before tcp_sk_exit_batch when a net namespace is destroyed since tcp_sk_ops is registered befrore ipv4_mib_ops, which means tcp_sk_ops is in the front of ipv4_mib_ops in the list of pernet_list. There will be a use-after-free on net->mib.net_statistics in tw_timer_handler after ipv4_mib_exit_net if there are some inflight time-wait timers. This bug is not introduced by commit f2bf415cfed7 (mib: add net to NET_ADD_STATS_BH) since the net_statistics is a global variable instead of dynamic allocation and freeing. Actually, commit 61a7e26028b9 (mib: put net statistics on struct net) introduces the bug since it put net statistics on struct net and free it when net namespace is destroyed. Moving init_ipv4_mibs() to the front of tcp_init() to fix this bug and replace pr_crit() with panic() since continuing is meaningless when init_ipv4_mibs() fails. [1] https://groups.google.com/g/syzkaller/c/p1tn-_Kc6l4/m/smuL_FMAAgAJ?pli=1
Priority: --
CVSS v3: 7.8
Component: linux
Publish Date: Feb 27, 2024
Related ID: --
CVSS v2: HIGH
Modified Date: Feb 27, 2024
Find out more about CVE-2021-46936 from the MITRE-CVE dictionary and NIST NVD
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| Product Name |
Status |
Defect |
Fixed |
Downloads |
| Linux |
| Wind River Linux LTS 17 |
Requires LTSS |
-- |
-- |
-- |
| Wind River Linux 8 |
Requires LTSS |
-- |
-- |
-- |
| Wind River Linux 9 |
Requires LTSS |
-- |
-- |
-- |
| Wind River Linux 7 |
Requires LTSS |
-- |
-- |
-- |
| Wind River Linux LTS 21 |
Fixed |
LIN1021-7413
|
10.21.20.11 |
-- |
| Wind River Linux LTS 22 |
Fixed |
LIN1022-6700
|
10.22.33.9 |
-- |
| Wind River Linux LTS 18 |
Requires LTSS |
-- |
-- |
-- |
| Wind River Linux LTS 19 |
Won't Fix |
-- |
-- |
-- |
| Wind River Linux CD release |
N/A |
-- |
-- |
-- |
| Wind River Linux 6 |
Requires LTSS |
-- |
-- |
-- |
| Wind River Linux LTS 23 |
Not Vulnerable |
-- |
-- |
-- |
| VxWorks |
| VxWorks 7 |
Not Vulnerable |
-- |
-- |
-- |
| VxWorks 6.9 |
Not Vulnerable |
-- |
-- |
-- |
| Helix Virtualization Platform Cert Edition |
| Helix Virtualization Platform Cert Edition |
Not Vulnerable |
-- |
-- |
-- |
| Product Name |
Status |
Defect |
Fixed |
Downloads |
Notes
Requires LTSS - customers must have active LTSS (Long Term Security Shield) Support to receive up-to-date information about vulnerabilities that may affect legacy software. Please contact your Wind River account team or see https://docs.windriver.com/bundle/Support_and_Maintenance_Supplemental_Terms_and_Conditions and https://support2.windriver.com/index.php?page=plc for more information.
