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CVE-2026-90140

cuse: wait for pending RCU callbacks on module exit

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.15.221, 6.1.188, 6.6.157, 6.12.110, 6.18.52, and 1 more
None on Exploit-DB, Metasploit or GitHub

Summary

In the Linux kernel, the following vulnerability has been resolved: cuse: wait for pending RCU callbacks on module exit Since commit 053fc4f755ad ("fuse: fix UAF in rcu pathwalks"), fuse_conn_put() frees the fuse_conn through call_rcu() rather than synchronously. For cuse, fc->release is cuse_fc_release(), which lives in the cuse module. If the module is removed before the RCU grace period ends, the callback jumps into freed module memory: userspace / module unload | RCU softirq ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ close(/dev/cuse) | cuse_channel_release() | fuse_dev_release() | fuse_conn_put(fch->conn) | call_rcu(delayed_release) ------+---> callback queued | rmmod cuse | cuse_exit() | cuse_channel_destroy() | ... | return | | <module text freed> | | rcu_do_batch() | delayed_release() | fc->release() | -> cuse_fc_release() | ^^^ freed text! The freed module text is unmapped by vfree(), so the jump into the stale callback triggers a page-fault Oops. If the virtual address is subsequently reused, the callback could execute unrelated code (undefined behaviour). Fix this by calling rcu_barrier() in cuse_exit() so that any pending fuse_conn release callback completes before the module is removed.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From bfbab62ca69f72bcd14ea30de1fb98f6080ad464 · fixed in 7fe415e1cd8fa875be263670c0ab47109818abb6; From a8f650b93e55764ca9ff8e1ddebc151f57024086 · fixed in 45ae914b2f6ea56fc2f1c017fdee4e995bcb4c0e; From 535e9bd0e8f8d8cfdc29de7cdb902b5041427fe6 · fixed in ac5c499413385cea3e0220d6050408d50842891d; From 053fc4f755ad43cf35210677bcba798ccdc48d0c · fixed in a1b46aee33d83f14ed62d7fdef1a91d3e0b732a9; From 053fc4f755ad43cf35210677bcba798ccdc48d0c · fixed in 389bd349ddbcf90dbd8a4f2a4ab6e552d53df134; From 053fc4f755ad43cf35210677bcba798ccdc48d0c · fixed in c40f3f24839f8404325a2099e26c2a04786ae309; From 053fc4f755ad43cf35210677bcba798ccdc48d0c · fixed in 4deb3edead0c0e172cc7349e8855d741d3c5e162; From 5.15.166 · fixed in 5.15.221; From 6.1.107 · fixed in 6.1.188; From 6.6.48 · fixed in 6.6.157

  • Linux Linux

    6.8

  • KernelLinux

    fixed in 5.15.221; From 5.16.0 · fixed in 6.1.188; From 6.2.0 · fixed in 6.6.157; From 6.7.0 · fixed in 6.12.110; From 6.8.0 · fixed in 6.18.52; From 6.13.0 · fixed in 7.2.6

References 7

git.kernel.org