CVE-2026-53256

Summary

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

Bluetooth: RFCOMM: hold listener socket in rfcomm_connect_ind()

rfcomm_get_sock_by_channel() scans rfcomm_sk_list under the list lock, but returns the selected listener after dropping that lock without taking a reference. rfcomm_connect_ind() then locks the listener, queues a child socket on it, and may notify it after unlocking it.

The buggy scenario involves two paths, with each column showing the order within that path:

rfcomm_connect_ind(): listener close:

  1. Find parent in 1. close() enters rfcomm_get_sock_by_channel() rfcomm_sock_release().
  2. Drop rfcomm_sk_list.lock 2. rfcomm_sock_shutdown() without pinning parent. closes the listener.
  3. Call lock_sock(parent) and 3. rfcomm_sock_kill() bt_accept_enqueue(parent, unlinks and puts parent. sk, true).
  4. Read parent flags and may 4. parent can be freed. call sk_state_change().

If close wins the race, parent can be freed before rfcomm_connect_ind() reaches lock_sock(), bt_accept_enqueue(), or the deferred-setup callback.

Take a reference on the listener before leaving rfcomm_sk_list.lock. After lock_sock() succeeds, recheck that it is still in BT_LISTEN before queueing a child, cache the deferred-setup bit while the parent is locked, and drop the reference after the last parent use.

KASAN reported a slab-use-after-free in lock_sock_nested() from rfcomm_connect_ind(), with the freeing stack going through rfcomm_sock_kill() and rfcomm_sock_release().

Affected Software

VendorProductVersion RangeStatus
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < f5ec76bdbeb80f75ad0be204371afffee0f8fac8affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < a07d741c077d4e34b16458241a94d29039386553affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 1f73f92f66251065a5f39b09a47cf05ea14d3107affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < de31973ef00e5aa55496f84cf6a44bb157a34e02affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < b0e33e409715c617e2a20f46f99aa5403a14dfdaaffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 8802413ce63175fb522a2bd609fb043a3550c720affected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 6f4462d12133106460d7c046b95aad2491e3fddfaffected
LinuxLinux1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 43c441edacf953b39517a44f5e5e10a93618b226affected
LinuxLinux2.6.12affected
LinuxLinux0 < 2.6.12unaffected
LinuxLinux5.10.259 <= 5.10.*unaffected
LinuxLinux5.15.210 <= 5.15.*unaffected
LinuxLinux6.1.176 <= 6.1.*unaffected
LinuxLinux6.6.143 <= 6.6.*unaffected
LinuxLinux6.12.94 <= 6.12.*unaffected
LinuxLinux6.18.36 <= 6.18.*unaffected
LinuxLinux7.0.13 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References