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; -- 2.39.3
