From: Chen Zhongjin <chenzhongjin@xxxxxxxxxx> [ Upstream commit c42c0ffe81176940bd5dead474216b7198d77675 ] syzkaller reported a memleak: https://syzkaller.appspot.com/bug?id=62f37ff612f0021641eda5b17f056f1668aa9aed unreferenced object 0xffff88811009c7f8 (size 136): ... backtrace: [<ffffffff821db19b>] z_erofs_do_read_page+0x99b/0x1740 [<ffffffff821dee9e>] z_erofs_readahead+0x24e/0x580 [<ffffffff814bc0d6>] read_pages+0x86/0x3d0 ... syzkaller constructed a case: in z_erofs_register_pcluster(), ztailpacking = false and map->m_pa = zero. This makes pcl->obj.index be zero although pcl is not a inline pcluster. Then following path adds refcount for grp, but the refcount won't be put because pcl is inline. z_erofs_readahead() z_erofs_do_read_page() # for another page z_erofs_collector_begin() erofs_find_workgroup() erofs_workgroup_get() Since it's illegal for the block address of a non-inlined pcluster to be zero, add check here to avoid registering the pcluster which would be leaked. Fixes: cecf864d3d76 ("erofs: support inline data decompression") Reported-by: syzbot+6f8cd9a0155b366d227f@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Chen Zhongjin <chenzhongjin@xxxxxxxxxx> Reviewed-by: Yue Hu <huyue2@xxxxxxxxxxx> Reviewed-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> Reviewed-by: Chao Yu <chao@xxxxxxxxxx> Link: https://lore.kernel.org/r/Y42Kz6sVkf+XqJRB@debian Signed-off-by: Gao Xiang <hsiangkao@xxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- fs/erofs/zdata.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c index b792d424d774..cf4871834ebb 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -488,7 +488,8 @@ static int z_erofs_register_pcluster(struct z_erofs_decompress_frontend *fe) struct erofs_workgroup *grp; int err; - if (!(map->m_flags & EROFS_MAP_ENCODED)) { + if (!(map->m_flags & EROFS_MAP_ENCODED) || + (!ztailpacking && !(map->m_pa >> PAGE_SHIFT))) { DBG_BUGON(1); return -EFSCORRUPTED; } -- 2.35.1
