From 7de5ae52b126f4f2c0ff614a9906eb12529f5b08 Mon Sep 17 00:00:00 2001 From: Gao Xiang Date: Mon, 4 Mar 2024 11:53:39 +0800 Subject: [PATCH] UPSTREAM: erofs: fix uninitialized page cache reported by KMSAN 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@google.com Bug: 353575918 Reported-and-tested-by: syzbot+7bc44a489f0ef0670bd5@syzkaller.appspotmail.com Fixes: 1ca01520148a ("erofs: refine z_erofs_transform_plain() for sub-page block support") Reviewed-by: Sandeep Dhavale Reviewed-by: Yue Hu Reviewed-by: Chao Yu Change-Id: I7a8e0bc81c1f4512d3640b243e8124a61d849028 Signed-off-by: Gao Xiang Link: https://lore.kernel.org/r/20240304035339.425857-1-hsiangkao@linux.alibaba.com (cherry picked from commit 893e5e9b7369a02e7ceaa6d98db6739162005b03) Signed-off-by: Sandeep Dhavale --- 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 943a35ccc953..7e87c43cf27e 100644 --- a/fs/erofs/decompressor.c +++ b/fs/erofs/decompressor.c @@ -330,7 +330,8 @@ 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;