On Mon, May 27, 2024 at 08:23:59AM +0200, Takashi Iwai wrote: > commit 4a63bd179fa8d3fcc44a0d9d71d941ddd62f0c4e upstream. > > Currently ALSA timer doesn't have the lower limit of the start tick > time, and it allows a very small size, e.g. 1 tick with 1ns resolution > for hrtimer. Such a situation may lead to an unexpected RCU stall, > where the callback repeatedly queuing the expire update, as reported > by fuzzer. > > This patch introduces a sanity check of the timer start tick time, so > that the system returns an error when a too small start size is set. > As of this patch, the lower limit is hard-coded to 100us, which is > small enough but can still work somehow. > > [ backport note: the error handling is changed, as the original commit > is based on the recent cleanup with guard() in commit beb45974dd49 > -- tiwai ] > > Reported-by: syzbot+43120c2af6ca2938cc38@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://lore.kernel.org/r/000000000000fa00a1061740ab6d@xxxxxxxxxx > Cc: <stable@xxxxxxxxxxxxxxx> > Link: https://lore.kernel.org/r/20240514182745.4015-1-tiwai@xxxxxxx > Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> > --- > > Greg, this is an alternative fix to the original cherry-pick; apply > to 6.8.y and older stable kernels. Thanks! Now queued up, thanks! greg k-h
