On Mon, 2019-06-24 at 14:41:48 UTC, Frederic Barrat wrote: > If an ocxl device is unbound through sysfs at the same time its AFU is > being opened by a user process, the open code may dereference freed > stuctures, which can lead to kernel oops messages. You'd have to hit a > tiny time window, but it's possible. It's fairly easy to test by > making the time window bigger artificially. > > Fix it with a combination of 2 changes: > - when an AFU device is found in the IDR by looking for the device > minor number, we should hold a reference on the device until after the > context is allocated. A reference on the AFU structure is kept when > the context is allocated, so we can release the reference on the > device after the context allocation. > - with the fix above, there's still another even tinier window, > between the time the AFU device is found in the IDR and the reference > on the device is taken. We can fix this one by removing the IDR entry > earlier, when the device setup is removed, instead of waiting for the > 'release' device callback. With proper locking around the IDR. > > Fixes: 75ca758adbaf ("ocxl: Create a clear delineation between ocxl backend & > frontend") > Signed-off-by: Frederic Barrat <fbar...@linux.ibm.com>
Applied to powerpc fixes, thanks. https://git.kernel.org/powerpc/c/a58d37bce0d21cf7fbd589384c619e465ef2f927 cheers