CVE-2026-68290

Summary

In the Linux kernel, the following vulnerability has been resolved:

rds: tcp: unregister sysctl before tearing down listen socket

rds_tcp_exit_net() frees the per-netns RDS TCP listen socket via rds_tcp_kill_sock() before unregistering the per-netns sysctl table. Since rds_tcp_skbuf_handler() derives the netns from rtn->rds_tcp_listen_sock->sk, a concurrent sysctl write can race with netns teardown and dereference the freed socket/sk.

KASAN reports the race as:

BUG: KASAN: slab-use-after-free in rds_tcp_skbuf_handler+0x2aa/0x2e0 rds_tcp_skbuf_handler net/rds/tcp.c:721 proc_sys_call_handler fs/proc/proc_sysctl.c vfs_write fs/read_write.c __x64_sys_pwrite64 fs/read_write.c

Fix this by unregistering the RDS TCP sysctl table before calling rds_tcp_kill_sock(). unregister_net_sysctl_table() prevents new sysctl handlers from starting and waits for in-flight handlers to finish, so the listen socket can then be released safely. The fix was tested against the linked reproducer.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/80fffed08dc1c10e971066941d2daa56253f1552
• https://git.kernel.org/stable/c/16df2d154ec82e2f7e7585b4fa154751ba37729a
• https://git.kernel.org/stable/c/3aa13fe0c1bb7bc5312f878e61523e5d8cf3f85d
• https://git.kernel.org/stable/c/167e54c703ccd4fa028feb568b0d1002020cff86

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