Tested in fresh torvalds/master branch. Thank you!
Best regards Anatoly пн, 29 окт. 2018 г. в 19:03, Nicolas Pitre <nicolas.pi...@linaro.org>: > > On Mon, 29 Oct 2018, Anatoly Trosinenko wrote: > > > > How do I populate /vtmp? Mine is empty at this point. I imagine I > > > should put the cramfs image somewhere on the host, but I'm not that > > > familiar withkvm. > > > > Oops, forgot to say, it is the /tmp/kvm-xfstests-$USER directory on > > the host (it will be created when you first launch kvm-xfstests and it > > is "live", i.e. like NFS, not like "pack to ext4 image then boot and > > mount"). > > OK, I reproduced it. The fix is as follows: > > diff --git a/fs/cramfs/inode.c b/fs/cramfs/inode.c > index f408994fc6..6e000392e4 100644 > --- a/fs/cramfs/inode.c > +++ b/fs/cramfs/inode.c > @@ -202,7 +202,8 @@ static void *cramfs_blkdev_read(struct super_block *sb, > unsigned int offset, > continue; > blk_offset = (blocknr - buffer_blocknr[i]) << PAGE_SHIFT; > blk_offset += offset; > - if (blk_offset + len > BUFFER_SIZE) > + if (blk_offset > BUFFER_SIZE || > + blk_offset + len > BUFFER_SIZE) > continue; > return read_buffers[i] + blk_offset; > } > > User space will get a bunch of zeroes rather than an explicit error in > this case. There is just so many ways to corrupt a cramfs image without > detecting it afterwards that I don't think it is worth doing more than > making sure the system won't be compromized. > > > > Hmmm... It doesn't show up on my test system. > > > > Mounted it on my host Ubuntu 18.10 amd64, executed `cat /mnt/xyz` and > > it was "Killed". Maybe it is something freshly added or > > arch-dependent... > > It actually depends on whether there is something mapped immediately > next to the cramfs cache buffer. > > In any case, this is a nice catch. Thank you for reporting it. > > > Nicolas
