Hi all, On Mon, Dec 05, 2022 at 11:49:57AM +0800, Chen Zhongjin wrote: > 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 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+6f8cd9a0155b366d2...@syzkaller.appspotmail.com > Signed-off-by: Chen Zhongjin <chenzhong...@huawei.com> > --- > v1 -> v2: > As Gao's advice, we should fail to register pcluster if m_pa is zero. > Maked it this way and changed the commit message. > > v2 -> v3: > Slightly fix commit message and add -next tag.
I've updated the patch itself as below (Since we only need to fail out for non-tailpacking cases, tailpacking inline inodes could still have m_pa < EROFS_BLKSIZ): >From f5e037e760d338ca0c116e507be663cb843d42f0 Mon Sep 17 00:00:00 2001 From: Chen Zhongjin <chenzhong...@huawei.com> Date: Mon, 5 Dec 2022 11:49:57 +0800 Subject: [PATCH] erofs: Fix pcluster memleak when its block address is zero 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+6f8cd9a0155b366d2...@syzkaller.appspotmail.com Signed-off-by: Chen Zhongjin <chenzhong...@huawei.com> Reviewed-by: Yue Hu <huy...@coolpad.com> Reviewed-by: Gao Xiang <hsiang...@linux.alibaba.com> Signed-off-by: Gao Xiang <hsiang...@linux.alibaba.com> --- 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 2584a62c9d28..fa7ac499a825 100644 --- a/fs/erofs/zdata.c +++ b/fs/erofs/zdata.c @@ -496,7 +496,8 @@ 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; } -- 2.30.2
