On 6/19/20 2:47 PM, Luis Chamberlain wrote: > Its been a fun ride, but all patch series come to an end. My hope is > that this is it. The simplification of the fix is considerable now, > with only a few lines of code and with no data structure changes. > > We were only creating the debugfs_dir upon initialization only if > you had CONFIG_BLK_DEBUG_FS for for make_request block drivers > (multiqueue). That's where the UAF bug could happen. Folks liked > the idea of open coding the debugfs initialization even if > CONFIG_BLK_DEBUG_FS was disabled, given that debugfs code will > simply ignore that code if debugfs is disabled, but to make > the fix easier to backport, that shift is done now in another > patch. Likewise, although we were only creating the debugfs_dir > only for make_request block drivers (multiqueue), the same new > additional patch also creates the debugfs_dir for request-based > block drivers. That *begged* us to just rename the mutex to > clarify its for the debugfs_dir, blktrace then just becomes > its biggest user. > > The only patches changed here is the last one from the last series, > which actually fixed the UAF oops, and that one is now split in 3 > patches, which makes a secondary fix much clearer. > > I've waited a while to post these, to let 0-day give me its blessings, > both for Linus' tree and linux-next. No issues have been found. I've > also taken time to run blktests prior and after this series and I have > found no regressions. In fact, I think I should just extend blktests > with the break-blktrace tests, I'll do that later. > > Luis Chamberlain (8): > block: add docs for gendisk / request_queue refcount helpers > block: clarify context for refcount increment helpers > block: revert back to synchronous request_queue removal > blktrace: annotate required lock on do_blk_trace_setup() > loop: be paranoid on exit and prevent new additions / removals > blktrace: fix debugfs use after free > blktrace: ensure our debugfs dir exists > block: create the request_queue debugfs_dir on registration Applied for 5.9, thanks. -- Jens Axboe
