On Wed, Nov 24, 2021 at 05:21:26PM +0100, Miklos Szeredi wrote: > On Wed, Nov 24, 2021 at 1:04 PM Greg Kroah-Hartman > <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > From: Miklos Szeredi <mszeredi@xxxxxxxxxx> > > > > commit 712a951025c0667ff00b25afc360f74e639dfabe upstream. > > > > It is possible to trigger a crash by splicing anon pipe bufs to the fuse > > device. > > > > The reason for this is that anon_pipe_buf_release() will reuse buf->page if > > the refcount is 1, but that page might have already been stolen and its > > flags modified (e.g. PG_lru added). > > > > This happens in the unlikely case of fuse_dev_splice_write() getting around > > to calling pipe_buf_release() after a page has been stolen, added to the > > page cache and removed from the page cache. > > > > Fix by calling pipe_buf_release() right after the page was inserted into > > the page cache. In this case the page has an elevated refcount so any > > release function will know that the page isn't reusable. > > > > Reported-by: Frank Dinoff <fdinoff@xxxxxxxxxx> > > Link: https://lore.kernel.org/r/CAAmZXrsGg2xsP1CK+cbuEMumtrqdvD-NKnWzhNcvn71RV3c1yw@xxxxxxxxxxxxxx/ > > Fixes: dd3bb14f44a6 ("fuse: support splice() writing to fuse device") > > Cc: <stable@xxxxxxxxxxxxxxx> # v2.6.35 > > Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> > > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > > Hi Greg, > > This patch turned out to have a bug, so stable releases that didn't > yet have it released might be better off backing it out for now and > releasing only together with the fix to avoid regressions. Good idea, now dropped from all of those queues. greg k-h
