On Mon, 2018-12-10 at 08:32 -0700, Keith Busch wrote: > On Sun, Dec 09, 2018 at 07:08:14PM -0800, Bart Van Assche wrote: > > According to what I found in > > https://bugzilla.kernel.org/show_bug.cgi?id=201935 patch "block: > > Clear > > kernel memory before copying to user" broke tape access. Hence > > revert > > that patch. > > Instead of reverting back to the leaking arbitrary kernel memory, why > not just make a fix on top of it? This should do it: > > --- > diff --git a/block/bio.c b/block/bio.c > index c4ef8aa46452..55a5386fd431 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -1262,7 +1262,8 @@ struct bio *bio_copy_user_iov(struct > request_queue *q, > if (ret) > goto cleanup; > } else { > - zero_fill_bio(bio); > + if (bmd->is_our_pages) > + zero_fill_bio(bio); > iov_iter_advance(iter, bio->bi_iter.bi_size); > } > > -- Reproduced on 4.20-rc6 # tar cvf /dev/st0 /etc ... Showed data was written in tar However listing is empty, data not actually written # tar tvf /dev/st0 # Then: Applied Keith Patch # tar cvf /dev/st0 /etc ... # tar tvf /dev/st0 Data was written and can be read ..drwxr-xr-x root/root 0 2018-10-31 08:41 etc/fwupd/ -rw-r--r-- root/root 292 2018-06-07 08:27 etc/fwupd/daemon.conf drwxr-xr-x root/root 0 2018-10-31 08:41 etc/fwupd/remotes.d/ -rw-r--r-- root/root 181 2018-09-05 06:00 etc/fwupd/remotes.d/fwupd.conf -rw-r--r-- root/root 327 2018-06-07 08:27 etc/fwupd/remotes.d/lvfs-testing.conf -rw-r--r-- root/root 283 2018-09-05 06:00 etc/fwupd/remotes.d/lvfs.conf -rw-r--r-- root/root 283 2018-09-05 06:00 etc/fwupd/remotes.d/vendor.conf -rw-r--r-- root/root 118 2018-09-05 06:00 etc/fwupd/uefi.conf -r--r----- root/root 4328 2018-09-25 01:57 etc/sudoers.rpmnew -rw-r--r-- root/root 2331 2018-11-02 14:50 etc/hercules.cnf -rw-r--r-- root/root 147 2018-11-06 17:08 etc/minirc.p2000 [ 96.272548] st 2:0:0:0: [st0] Block limits 1 - 16777215 bytes. [ 96.300782] st 2:0:0:0: [st0] Mode sense. Length 11, medium 0, WBS 10, BLL 8 [ 96.334985] st 2:0:0:0: [st0] Density 58, tape length: 0, drv buffer: 1 [ 96.367366] st 2:0:0:0: [st0] Block size: 0, buffer size: 4096 (1 blocks). [ 97.197209] st 2:0:0:0: [st0] Rewinding tape. [ 103.104429] st 2:0:0:0: [st0] Block limits 1 - 16777215 bytes. [ 103.133142] st 2:0:0:0: [st0] Mode sense. Length 11, medium 0, WBS 10, BLL 8 [ 103.167421] st 2:0:0:0: [st0] Density 58, tape length: 0, drv buffer: 1 [ 103.199711] st 2:0:0:0: [st0] Block size: 0, buffer size: 4096 (1 blocks). [ 104.109081] st 2:0:0:0: [st0] Rewinding tape. Tested and works fine. Thanks All Tested-by: Laurence Oberman <loberman@xxxxxxxxxx>
