mmc: vub300: fix use-after-free on probe failure

Summary

In the Linux kernel, the following vulnerability has been resolved: mmc: vub300: fix use-after-free on probe failure The vub300 driver lifetime-manages its controller state using vub300->kref, with vub300_delete() freeing the mmc host when the last reference is dropped. The probe error path after the inactivity timer has been armed still bypasses that lifetime rule, however, and falls through to mmc_free_host() directly if mmc_add_host() fails. The race window is between arming the inactivity timer and reaching the probe error unwind after mmc_add_host() fails: probe thread timer/workqueue ------------ --------------- kref_init(&vub300->kref) ref = 1 kref_get(&vub300->kref) ref = 2, timer ref add_timer(inactivity_timer) fires after one second | | race window |<----------------------------------------------------> | mmc_add_host(mmc) inactivity timer fires vub300_queue_dead_work() kref_get() ref = 3 queue_work(deadwork) mmc_add_host() fails timer_delete_sync() mmc_free_host(mmc) frees vub300 deadwork runs use-after-free The inactivity timeout is one second, so this would require mmc_add_host() to both fail and take more than one second to do so. This is unlikely to happen in practice, but the error path is still wrong. timer_delete_sync() only waits for the timer callback itself. It does not flush deadwork that the callback may already have queued. As a result, queued deadwork can still hold a kref while the probe error path directly frees the backing mmc host, including the vub300 storage. Fix this by using the same lifetime mechanism as disconnect. Clear vub300->interface so that the timer callback and any queued deadwork return early and drop their references, then drop the initial probe reference and return without falling through to err_free_host.

Timeline

1. Aug 15, 2026, 5:52 AM UTCCVE published
2. Oct 21, 2026, 12:44 PM UTCRecord last updated

Affected versions

• Linux Linux

  From 0613ad2401f88bdeae5594c30afe318e93b14676 · fixed in face65f80c6946c631ca3490b4ebd2c016a4fd2c; From 0613ad2401f88bdeae5594c30afe318e93b14676 · fixed in 6c66653dac9b25272d5fd4ed42a34aa5249e16df; From 0613ad2401f88bdeae5594c30afe318e93b14676 · fixed in 5b82af744e06cd741938c3da54fdbe564a7e52d9; From 0613ad2401f88bdeae5594c30afe318e93b14676 · fixed in 618cf6b139503ec18ef93ffd663396aaf99b763a; From 0613ad2401f88bdeae5594c30afe318e93b14676 · fixed in a3b5f242997a3be7404112fd48784881560aea57; From 4.9.337 · fixed in 4.10; From 4.14.303 · fixed in 4.15; From 4.19.270 · fixed in 4.20; From 5.4.229 · fixed in 5.5; From 5.10.163 · fixed in 5.11; From 5.15.86 · fixed in 5.16; From 6.0.16 · fixed in 6.1; From 6.1.2 · fixed in 6.2

• Linux Linux

  6.2

• KernelLinux

  From 6.2.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.114; From 6.13.0 · fixed in 6.18.42; From 6.19.0 · fixed in 7.1.5

References 5