From: Chen Zhongjin <chenzhongjin@huawei.com> To: <syzbot+6f8cd9a0155b366d227f@syzkaller.appspotmail.com>, <linux-erofs@lists.ozlabs.org>, <linux-kernel@vger.kernel.org> Cc: <chenzhongjin@huawei.com>, <xiang@kernel.org>, <chao@kernel.org>, <huyue2@coolpad.com>, <jefflexu@linux.alibaba.com> Subject: [PATCH v2] erofs: Fix pcluster memleak when m_pa is zero Date: Mon, 5 Dec 2022 09:50:24 +0800 [thread overview] Message-ID: <20221205015024.66868-1-chenzhongjin@huawei.com> (raw) 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 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> --- 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
WARNING: multiple messages have this Message-ID (diff)
From: Chen Zhongjin via Linux-erofs <linux-erofs@lists.ozlabs.org> To: <syzbot+6f8cd9a0155b366d227f@syzkaller.appspotmail.com>, <linux-erofs@lists.ozlabs.org>, <linux-kernel@vger.kernel.org> Cc: chenzhongjin@huawei.com, huyue2@coolpad.com Subject: [PATCH v2] erofs: Fix pcluster memleak when m_pa is zero Date: Mon, 5 Dec 2022 09:50:24 +0800 [thread overview] Message-ID: <20221205015024.66868-1-chenzhongjin@huawei.com> (raw) 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 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> --- 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
next reply other threads:[~2022-12-05 1:53 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-12-05 1:50 Chen Zhongjin [this message] 2022-12-05 1:50 ` [PATCH v2] erofs: Fix pcluster memleak when m_pa is zero Chen Zhongjin via Linux-erofs 2022-12-05 3:46 ` Gao Xiang 2022-12-05 3:46 ` Gao Xiang
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