cbcvebase.
CVE-2021-46936
published 2024-02-27

CVE-2021-46936: 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…

PriorityP338high7.8CVSS 3.1
AVLACLPRLUINSUCHIHAH
EPSS
0.24%
15.7th percentile
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

Affected

22 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 5.15.15-1 (bookworm)linux 5.15.15-1 (bookworm)
linuxlinux
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < 15579e1301f856ad9385d720c9267c11032a502215579e1301f856ad9385d720c9267c11032a5022
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < e73164e89d1be561228a4534e1091369ee4ba41ae73164e89d1be561228a4534e1091369ee4ba41a
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < 5c2fe20ad37ff56070ae0acb34152333976929b45c2fe20ad37ff56070ae0acb34152333976929b4
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < a8e1944b44f94f5c5f530e434c5eaee787254566a8e1944b44f94f5c5f530e434c5eaee787254566
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < fe5838c22b986c1190f1dce9aa09bf6a491c1a69fe5838c22b986c1190f1dce9aa09bf6a491c1a69
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < 2386e81a1d277f540e1285565c9d41d531bb69d42386e81a1d277f540e1285565c9d41d531bb69d4
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < 08eacbd141e2495d2fcdde84358a06c4f95cbb1308eacbd141e2495d2fcdde84358a06c4f95cbb13
linuxlinux>= 61a7e26028b94805fd686a6dc9dbd9941f8f19b0 < e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0e22e45fc9e41bf9fcc1e92cfb78eb92786728ef0
linuxlinux_kernel>= 0 < 5.10.92-15.10.92-1
linuxlinux_kernel>= 0 < 5.15.15-15.15.15-1
linuxlinux_kernel>= 0 < 5.15.15-15.15.15-1
linuxlinux_kernel>= 0 < 5.15.15-15.15.15-1
linuxlinux_kernel>= 0 < 4.4.0-253.2874.4.0-253.287
linuxlinux_kernel>= 2.6.27 < 4.4.2984.4.298
linuxlinux_kernel>= 4.10.0 < 4.14.2614.14.261
linuxlinux_kernel>= 4.15.0 < 4.19.2244.19.224
linuxlinux_kernel>= 4.20.0 < 5.4.1705.4.170
linuxlinux_kernel>= 4.5.0 < 4.9.2964.9.296
linuxlinux_kernel>= 5.11.0 < 5.15.135.15.13
linuxlinux_kernel>= 5.5.0 < 5.10.905.10.90

CVSS provenance

nvdv3.17.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
osv7.8HIGH
vendor_debian7.8HIGH
vendor_redhat7.8HIGH
vendor_ubuntu7.0HIGH
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