Messages in this thread |  | | Date | Mon, 5 Dec 2022 11:46:30 +0800 | From | Gao Xiang <> | Subject | Re: [PATCH v2] erofs: Fix pcluster memleak when m_pa is zero |
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On Mon, Dec 05, 2022 at 09:50:24AM +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 map->m_pa to be zero, add check here to avoid
the block address of a pcluster to be zero,
not just map->m_pa == 0.
Also subject line needs to be updated as well, "Fix pcluster memleak when its block address is zero"
> registering the pcluster which would be leaked. > > Fixes: cecf864d3d76 ("erofs: support inline data decompression") > Reported-by: syzbot+6f8cd9a0155b366d227f@syzkaller.appspotmail.com > Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Otherwise it looks good to me,
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
(Would you mind sending a next version for this so I can apply it?)
Thanks, Gao Xiang
> --- > As Gao's advice, we should fail to register pcluster if m_pa is zero. > Maked it this way and changed the commit message. > --- > 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..7826634f4f51 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) || > + !(map->m_pa >> PAGE_SHIFT)) { > DBG_BUGON(1); > return -EFSCORRUPTED; > } > -- > 2.17.1
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