cbcvebase.
CVE-2024-44991
published 2024-09-04

CVE-2024-44991: In the Linux kernel, the following vulnerability has been resolved: tcp: prevent concurrent execution of tcp_sk_exit_batch Its possible that two threads call…

PriorityP420medium5.5CVSS 3.1
AVLACLPRLUINSUCNINAH
EPSS
0.24%
15.8th percentile
In the Linux kernel, the following vulnerability has been resolved: tcp: prevent concurrent execution of tcp_sk_exit_batch Its possible that two threads call tcp_sk_exit_batch() concurrently, once from the cleanup_net workqueue, once from a task that failed to clone a new netns. In the latter case, error unwinding calls the exit handlers in reverse order for the 'failed' netns. tcp_sk_exit_batch() calls tcp_twsk_purge(). Problem is that since commit b099ce2602d8 ("net: Batch inet_twsk_purge"), this function picks up twsk in any dying netns, not just the one passed in via exit_batch list. This means that the error unwind of setup_net() can "steal" and destroy timewait sockets belonging to the exiting netns. This allows the netns exit worker to proceed to call WARN_ON_ONCE(!refcount_dec_and_test(&net->ipv4.tcp_death_row.tw_refcount)); without the expected 1 -> 0 transition, which then splats. At same time, error unwind path that is also running inet_twsk_purge() will splat as well: WARNING: .. at lib/refcount.c:31 refcount_warn_saturate+0x1ed/0x210 ... refcount_dec include/linux/refcount.h:351 [inline] inet_twsk_kill+0x758/0x9c0 net/ipv4/inet_timewait_sock.c:70 inet_twsk_deschedule_put net/ipv4/inet_timewait_sock.c:221 inet_twsk_purge+0x725/0x890 net/ipv4/inet_timewait_sock.c:304 tcp_sk_exit_batch+0x1c/0x170 net/ipv4/tcp_ipv4.c:3522 ops_exit_list+0x128/0x180 net/core/net_namespace.c:178 setup_net+0x714/0xb40 net/core/net_namespace.c:375 copy_net_ns+0x2f0/0x670 net/core/net_namespace.c:508 create_new_namespaces+0x3ea/0xb10 kernel/nsproxy.c:110 ... because refcount_dec() of tw_refcount unexpectedly dropped to 0. This doesn't seem like an actual bug (no tw sockets got lost and I don't see a use-after-free) but as erroneous trigger of debug check. Add a mutex to force strict ordering: the task that calls tcp_twsk_purge() blocks other task from doing final _dec_and_test before mutex-owner has removed all tw sockets of dying netns.

Affected

19 ranges
VendorProductVersion rangeFixed in
debianlinux< linux 6.1.112-1 (bookworm)linux 6.1.112-1 (bookworm)
debianlinux-6.1< linux 6.1.112-1 (bookworm)linux 6.1.112-1 (bookworm)
linuxlinux
linuxlinux>= e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8 < e3d9de3742f4d5c47ae35f888d3023a5b54fcd2fe3d9de3742f4d5c47ae35f888d3023a5b54fcd2f
linuxlinux>= e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8 < 99580ae890ec8bd98b21a2a9c6668f8f1555b62e99580ae890ec8bd98b21a2a9c6668f8f1555b62e
linuxlinux>= e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8 < f6fd2dbf584a4047ba88d1369ff91c9851261ec1f6fd2dbf584a4047ba88d1369ff91c9851261ec1
linuxlinux>= e9bd0cca09d13ac2f08d25e195203e42d4ad1ce8 < 565d121b69980637f040eb4d84289869cdaabedf565d121b69980637f040eb4d84289869cdaabedf
linuxlinux_kernel
linuxlinux_kernel>= 0 < 6.1.112-16.1.112-1
linuxlinux_kernel>= 0 < 6.10.7-16.10.7-1
linuxlinux_kernel>= 0 < 6.10.7-16.10.7-1
linuxlinux_kernel>= 0 < 6.8.0-50.516.8.0-50.51
linuxlinux_kernel>= 6.1 < 6.1.1076.1.107
linuxlinux_kernel>= 6.2 < 6.6.486.6.48
linuxlinux_kernel>= 6.7 < 6.10.76.10.7
msrcazl3_kernel_6.6.47.1-1_on_azure_linux_3.0
msrcazl3_kernel_6.6.51.1-5_on_azure_linux_3.0
msrcazure_linux_3.0_arm
msrcazure_linux_3.0_x64

CVSS provenance

nvdv3.15.5MEDIUMCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
osv5.5MEDIUM
vendor_debian5.5MEDIUM
vendor_msrc5.5MEDIUM
vendor_redhat5.5MEDIUM
vendor_ubuntu5.5MEDIUM
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