cifs: Fix server use-after-free in cifs_chan_skip_or_disable()

Summary

In the Linux kernel, the following vulnerability has been resolved: cifs: Fix server use-after-free in cifs_chan_skip_or_disable() When a secondary channel is no longer supported by the server, cifs_chan_skip_or_disable() drops the channel reference with cifs_put_tcp_session() and then continues to use the server pointer by calling cifs_signal_cifsd_for_reconnect() on it and reading its primary_server pointer. cifs_put_tcp_session() can drop the last reference of the channel and tear it down, so both the channel and the primary server (whose reference is also dropped by cifs_put_tcp_session()) can be freed before they are signaled for reconnect. Signal the channel and the primary server and capture the primary server pointer before dropping the channel reference with cifs_put_tcp_session().

Timeline

1. Oct 6, 2026, 8:45 AM UTCCVE published
2. Oct 19, 2026, 9:16 AM UTCRecord last updated

Affected versions

• Linux Linux

  From 50e8363ecc85da49764781da90ebffe1a657b370 · fixed in 0338489960ddad6368bce55e8adbc176c523093d; From f591062bdbf4742b7f1622173017f19e927057b0 · fixed in edd52eae5fcfb8433b6bb0e7cd98db438fe01227; From f591062bdbf4742b7f1622173017f19e927057b0 · fixed in fcc0a935bb6e37ecbf7e4335061309f896f35780; From f591062bdbf4742b7f1622173017f19e927057b0 · fixed in 7a1b27780b113583a94256d58dabfe7c0d9286e7; From f591062bdbf4742b7f1622173017f19e927057b0 · fixed in 717e0a25036b6c92cecace30913b2d874a4c22b8; From 6.6.15 · fixed in 6.6.158; From 6.7.3 · fixed in 6.8

• Linux Linux

  6.8

• KernelLinux

  fixed in 6.6.158; From 6.7.0 · fixed in 6.12.112; From 6.8.0 · fixed in 6.18.54; From 6.13.0 · fixed in 7.2.8

References 5