On Mon, 4 Mar 2024 11:53:39 +0800 Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> wrote: > syzbot reports a KMSAN reproducer [1] which generates a crafted > filesystem image and causes IMA to read uninitialized page cache. > > Later, (rq->outputsize > rq->inputsize) will be formally supported > after either large uncompressed pclusters (> block size) or big > lclusters are landed. However, currently there is no way to generate > such filesystems by using mkfs.erofs. > > Thus, let's mark this condition as unsupported for now. > > [1] https://lore.kernel.org/r/0000000000002be12a0611ca7ff8@xxxxxxxxxx > > Reported-by: syzbot+7bc44a489f0ef0670bd5@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 1ca01520148a ("erofs: refine z_erofs_transform_plain() for sub-page block support") > Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> > --- > fs/erofs/decompressor.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/fs/erofs/decompressor.c b/fs/erofs/decompressor.c > index d4cee95af14c..2ec9b2bb628d 100644 > --- a/fs/erofs/decompressor.c > +++ b/fs/erofs/decompressor.c > @@ -323,7 +323,8 @@ static int z_erofs_transform_plain(struct z_erofs_decompress_req *rq, > unsigned int cur = 0, ni = 0, no, pi, po, insz, cnt; > u8 *kin; > > - DBG_BUGON(rq->outputsize > rq->inputsize); > + if (rq->outputsize > rq->inputsize) > + return -EOPNOTSUPP; > if (rq->alg == Z_EROFS_COMPRESSION_INTERLACED) { > cur = bs - (rq->pageofs_out & (bs - 1)); > pi = (rq->pageofs_in + rq->inputsize - cur) & ~PAGE_MASK; Reviewed-by: Yue Hu <huyue2@xxxxxxxxxxx>
