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[PATCH -next v3] erofs: Fix pcluster memleak when its block address is zero

Chen Zhongjin posted 1 patch 1 year, 4 months ago 
fs/erofs/zdata.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
[PATCH -next v3] erofs: Fix pcluster memleak when its block address is zero
Posted by Chen Zhongjin 1 year, 4 months ago 
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+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
Signed-off-by: Chen Zhongjin <chenzhongjin@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.
---
 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
Re: [PATCH -next v3] erofs: Fix pcluster memleak when its block address is zero
Posted by Gao Xiang 1 year, 4 months ago 
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+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
> Signed-off-by: Chen Zhongjin <chenzhongjin@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 <chenzhongjin@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+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Gao Xiang <hsiangkao@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
Re: [PATCH -next v3] erofs: Fix pcluster memleak when its block address is zero
Posted by Chao Yu 1 year, 4 months ago 
On 2022/12/5 14:08, Gao Xiang wrote:
> 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+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
>> Signed-off-by: Chen Zhongjin <chenzhongjin@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 <chenzhongjin@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+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
> Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
> Reviewed-by: Yue Hu <huyue2@coolpad.com>
> Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
> Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Reviewed-by: Chao Yu <chao@kernel.org>

Thanks,
Re: [PATCH -next v3] erofs: Fix pcluster memleak when its block address is zero
Posted by Yue Hu 1 year, 4 months ago 
On Mon, 5 Dec 2022 11:49:57 +0800
Chen Zhongjin via Linux-erofs <linux-erofs@lists.ozlabs.org> 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+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
> Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>

Reviewed-by: Yue Hu <huyue2@coolpad.com>

Thanks.

> ---
> 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.
> ---
>  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;
>  	}
Re: [PATCH -next v3] erofs: Fix pcluster memleak when its block address is zero
Posted by Gao Xiang 1 year, 4 months ago 
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+6f8cd9a0155b366d227f@syzkaller.appspotmail.com
> Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>

Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>

Thanks,
Gao Xiang

Patchew 2.1-devel-0870f84

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