[v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

[PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Jeongjun Park 1 month ago

The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
To fix this, we need to add validation on a.data_type in 
alloc_lru_idx_fragmentation().

Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
---
 fs/bcachefs/alloc_background.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
index f8e87c6721b1..163a67b97a40 100644
--- a/fs/bcachefs/alloc_background.h
+++ b/fs/bcachefs/alloc_background.h
@@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
 static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
 					      struct bch_dev *ca)
 {
+	if (a.data_type >= BCH_DATA_NR)
+		return 0;
+
 	if (!data_type_movable(a.data_type) ||
 	    !bch2_bucket_sectors_fragmented(ca, a))
 		return 0;
--

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Kent Overstreet 1 month ago

On Tue, Oct 22, 2024 at 12:43:56AM +0900, Jeongjun Park wrote:
> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
> To fix this, we need to add validation on a.data_type in 
> alloc_lru_idx_fragmentation().
> 
> Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
> Signed-off-by: Jeongjun Park <aha310510@gmail.com>

Thanks, applied

> ---
>  fs/bcachefs/alloc_background.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
> index f8e87c6721b1..163a67b97a40 100644
> --- a/fs/bcachefs/alloc_background.h
> +++ b/fs/bcachefs/alloc_background.h
> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>  static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>  					      struct bch_dev *ca)
>  {
> +	if (a.data_type >= BCH_DATA_NR)
> +		return 0;
> +
>  	if (!data_type_movable(a.data_type) ||
>  	    !bch2_bucket_sectors_fragmented(ca, a))
>  		return 0;
> --

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Hongbo Li 1 month ago


On 2024/10/21 23:43, Jeongjun Park wrote:
> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
> To fix this, we need to add validation on a.data_type in
> alloc_lru_idx_fragmentation().
> 
> Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
> ---
>   fs/bcachefs/alloc_background.h | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
> index f8e87c6721b1..163a67b97a40 100644
> --- a/fs/bcachefs/alloc_background.h
> +++ b/fs/bcachefs/alloc_background.h
> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>   static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>   					      struct bch_dev *ca)
>   {
> +	if (a.data_type >= BCH_DATA_NR)
> +		return 0;
> +

oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?] 
UBSAN: shift-out-of-bounds in bch2_alloc_to_text"). But in my humble 
opinion, the validation changes also should be added. And in addition, 
move the condition about a.data_type into data_type_movable will be 
better. Just my personal opinion.:)

[1] https://www.spinics.net/lists/kernel/msg5412619.html

Thanks,
Hongbo

>   	if (!data_type_movable(a.data_type) ||
>   	    !bch2_bucket_sectors_fragmented(ca, a))
>   		return 0;
> --
>

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Kent Overstreet 1 month ago

On Tue, Oct 22, 2024 at 10:26:18AM +0800, Hongbo Li wrote:
> 
> 
> On 2024/10/21 23:43, Jeongjun Park wrote:
> > The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
> > To fix this, we need to add validation on a.data_type in
> > alloc_lru_idx_fragmentation().
> > 
> > Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
> > Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
> > Signed-off-by: Jeongjun Park <aha310510@gmail.com>
> > ---
> >   fs/bcachefs/alloc_background.h | 3 +++
> >   1 file changed, 3 insertions(+)
> > 
> > diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
> > index f8e87c6721b1..163a67b97a40 100644
> > --- a/fs/bcachefs/alloc_background.h
> > +++ b/fs/bcachefs/alloc_background.h
> > @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
> >   static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
> >   					      struct bch_dev *ca)
> >   {
> > +	if (a.data_type >= BCH_DATA_NR)
> > +		return 0;
> > +
> 
> oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?]
> UBSAN: shift-out-of-bounds in bch2_alloc_to_text"). But in my humble
> opinion, the validation changes also should be added. And in addition, move
> the condition about a.data_type into data_type_movable will be better. Just
> my personal opinion.:)

Unknown data types (and key types, btree IDs, etc.) are allowed for
forwards compatibility - they should just be ignored

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Jeongjun Park 1 month ago


> Hongbo Li <lihongbo22@huawei.com> wrote:
> 
> 
> 
>> On 2024/10/21 23:43, Jeongjun Park wrote:
>> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
>> To fix this, we need to add validation on a.data_type in
>> alloc_lru_idx_fragmentation().
>> Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
>> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
>> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
>> ---
>>  fs/bcachefs/alloc_background.h | 3 +++
>>  1 file changed, 3 insertions(+)
>> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
>> index f8e87c6721b1..163a67b97a40 100644
>> --- a/fs/bcachefs/alloc_background.h
>> +++ b/fs/bcachefs/alloc_background.h
>> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>>  static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>>                            struct bch_dev *ca)
>>  {
>> +    if (a.data_type >= BCH_DATA_NR)
>> +        return 0;
>> +
> 
> oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_alloc_to_text"). But in my humble opinion, the validation changes also should be added. And in addition, move the condition about a.data_type into data_type_movable will be better. Just my personal opinion.:)
> 
> [1] https://www.spinics.net/lists/kernel/msg5412619.html

I still disagree with the fix to make data_type_movable() do the validation, 
but I think [1] is definitely a patch that needs to be added. 

However, [1] is far from preventing the shift oob vulnerability described 
in that syzbot report. Therefore, I think [1] should be written as a 
standalone patch and committed, rather than as a patch for that 
syzbot report.

> 
> Thanks,
> Hongbo
> 
>>      if (!data_type_movable(a.data_type) ||
>>          !bch2_bucket_sectors_fragmented(ca, a))
>>          return 0;
>> --

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Hongbo Li 1 month ago


On 2024/10/22 12:05, Jeongjun Park wrote:
> 
> 
>> Hongbo Li <lihongbo22@huawei.com> wrote:
>>
>> 
>>
>>> On 2024/10/21 23:43, Jeongjun Park wrote:
>>> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
>>> To fix this, we need to add validation on a.data_type in
>>> alloc_lru_idx_fragmentation().
>>> Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
>>> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
>>> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
>>> ---
>>>   fs/bcachefs/alloc_background.h | 3 +++
>>>   1 file changed, 3 insertions(+)
>>> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
>>> index f8e87c6721b1..163a67b97a40 100644
>>> --- a/fs/bcachefs/alloc_background.h
>>> +++ b/fs/bcachefs/alloc_background.h
>>> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>>>   static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>>>                             struct bch_dev *ca)
>>>   {
>>> +    if (a.data_type >= BCH_DATA_NR)
>>> +        return 0;
>>> +
>>
>> oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_alloc_to_text"). But in my humble opinion, the validation changes also should be added. And in addition, move the condition about a.data_type into data_type_movable will be better. Just my personal opinion.:)
>>
>> [1] https://www.spinics.net/lists/kernel/msg5412619.html
> 
> I still disagree with the fix to make data_type_movable() do the validation,
> but I think [1] is definitely a patch that needs to be added.
> 
> However, [1] is far from preventing the shift oob vulnerability described
> in that syzbot report. Therefore, I think [1] should be written as a
> standalone patch and committed, rather than as a patch for that

I'm fine for this.:)

Thanks,
Hongbo

> syzbot report.
> 
>>
>> Thanks,
>> Hongbo
>>
>>>       if (!data_type_movable(a.data_type) ||
>>>           !bch2_bucket_sectors_fragmented(ca, a))
>>>           return 0;
>>> --

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Alan Huang 1 month ago

On Oct 22, 2024, at 10:26, Hongbo Li <lihongbo22@huawei.com> wrote:
> 
> 
> 
> On 2024/10/21 23:43, Jeongjun Park wrote:
>> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
>> To fix this, we need to add validation on a.data_type in
>> alloc_lru_idx_fragmentation().
>> Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
>> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
>> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
>> ---
>>  fs/bcachefs/alloc_background.h | 3 +++
>>  1 file changed, 3 insertions(+)
>> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
>> index f8e87c6721b1..163a67b97a40 100644
>> --- a/fs/bcachefs/alloc_background.h
>> +++ b/fs/bcachefs/alloc_background.h
>> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>>  static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>>         struct bch_dev *ca)
>>  {
>> + if (a.data_type >= BCH_DATA_NR)
>> + return 0;
>> +
> 
> oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_alloc_to_text"). But

Your patch there is still triggering the issue.

> in my humble opinion, the validation changes also should be added. And in addition, move the condition about a.data_type into

There is already the validation:

bkey_fsck_err_on(alloc_data_type(a, a.data_type) != a.data_type

And the unknown data type is already printed in bch2_prt_data_type, additional validation doesn’t help much.

> data_type_movable will be better. Just my personal opinion.:)

In my personal opinion, I don’t think so :)

> 
> [1] https://www.spinics.net/lists/kernel/msg5412619.html
> 
> Thanks,
> Hongbo
> 
>>   if (!data_type_movable(a.data_type) ||
>>       !bch2_bucket_sectors_fragmented(ca, a))
>>   return 0;
>> --

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Hongbo Li 1 month ago


On 2024/10/22 10:38, Alan Huang wrote:
> On Oct 22, 2024, at 10:26, Hongbo Li <lihongbo22@huawei.com> wrote:
>>
>>
>>
>> On 2024/10/21 23:43, Jeongjun Park wrote:
>>> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
>>> To fix this, we need to add validation on a.data_type in
>>> alloc_lru_idx_fragmentation().
>>> Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
>>> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
>>> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
>>> ---
>>>   fs/bcachefs/alloc_background.h | 3 +++
>>>   1 file changed, 3 insertions(+)
>>> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
>>> index f8e87c6721b1..163a67b97a40 100644
>>> --- a/fs/bcachefs/alloc_background.h
>>> +++ b/fs/bcachefs/alloc_background.h
>>> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>>>   static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>>>          struct bch_dev *ca)
>>>   {
>>> + if (a.data_type >= BCH_DATA_NR)
>>> + return 0;
>>> +
>>
>> oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_alloc_to_text"). But
> 
> Your patch there is still triggering the issue.
Yeah, it just notify the issue and not prevent the issue. So I found it 
should add a.data_type condition indeed. :)
> 
>> in my humble opinion, the validation changes also should be added. And in addition, move the condition about a.data_type into
> 
> There is already the validation:
> 
> bkey_fsck_err_on(alloc_data_type(a, a.data_type) != a.data_type

This is actually not enough. This only do some transition check. For 
example, if a.data_type break when bch2_bucket_sectors_dirty (the data 
corruption can lead to various situations occurring) is true, the helper 
does noting.

Thanks,
Hongbo

> 
> And the unknown data type is already printed in bch2_prt_data_type, additional validation doesn’t help much.
> 
>> data_type_movable will be better. Just my personal opinion.:)
> 
> In my personal opinion, I don’t think so :)
> 
>>
>> [1] https://www.spinics.net/lists/kernel/msg5412619.html
>>
>> Thanks,
>> Hongbo
>>
>>>    if (!data_type_movable(a.data_type) ||
>>>        !bch2_bucket_sectors_fragmented(ca, a))
>>>    return 0;
>>> --
> 
>

Re: [PATCH v3] bcachefs: fix shift oob in alloc_lru_idx_fragmentation

Posted by Alan Huang 1 month ago

On Oct 22, 2024, at 11:05, Hongbo Li <lihongbo22@huawei.com> wrote:
> 
> 
> 
> On 2024/10/22 10:38, Alan Huang wrote:
>> On Oct 22, 2024, at 10:26, Hongbo Li <lihongbo22@huawei.com> wrote:
>>> 
>>> 
>>> 
>>> On 2024/10/21 23:43, Jeongjun Park wrote:
>>>> The size of a.data_type is set abnormally large, causing shift-out-of-bounds.
>>>> To fix this, we need to add validation on a.data_type in
>>>> alloc_lru_idx_fragmentation().
>>>> Reported-by: syzbot+7f45fa9805c40db3f108@syzkaller.appspotmail.com
>>>> Fixes: 260af1562ec1 ("bcachefs: Kill alloc_v4.fragmentation_lru")
>>>> Signed-off-by: Jeongjun Park <aha310510@gmail.com>
>>>> ---
>>>>  fs/bcachefs/alloc_background.h | 3 +++
>>>>  1 file changed, 3 insertions(+)
>>>> diff --git a/fs/bcachefs/alloc_background.h b/fs/bcachefs/alloc_background.h
>>>> index f8e87c6721b1..163a67b97a40 100644
>>>> --- a/fs/bcachefs/alloc_background.h
>>>> +++ b/fs/bcachefs/alloc_background.h
>>>> @@ -168,6 +168,9 @@ static inline bool data_type_movable(enum bch_data_type type)
>>>>  static inline u64 alloc_lru_idx_fragmentation(struct bch_alloc_v4 a,
>>>>         struct bch_dev *ca)
>>>>  {
>>>> + if (a.data_type >= BCH_DATA_NR)
>>>> + return 0;
>>>> +
>>> 
>>> oh, I found I have done the same thing in [1]("Re: [syzbot] [bcachefs?] UBSAN: shift-out-of-bounds in bch2_alloc_to_text"). But
>> Your patch there is still triggering the issue.
> Yeah, it just notify the issue and not prevent the issue. So I found it should add a.data_type condition indeed. :)
>>> in my humble opinion, the validation changes also should be added. And in addition, move the condition about a.data_type into
>> There is already the validation:
>> bkey_fsck_err_on(alloc_data_type(a, a.data_type) != a.data_type
> 
> This is actually not enough. This only do some transition check. For example, if a.data_type break when bch2_bucket_sectors_dirty (the data corruption can lead to various situations occurring) is true, the helper does noting.

Make sense.

> 
> Thanks,
> Hongbo
> 
>> And the unknown data type is already printed in bch2_prt_data_type, additional validation doesn’t help much.
>>> data_type_movable will be better. Just my personal opinion.:)
>> In my personal opinion, I don’t think so :)
>>> 
>>> [1] https://www.spinics.net/lists/kernel/msg5412619.html
>>> 
>>> Thanks,
>>> Hongbo
>>> 
>>>>   if (!data_type_movable(a.data_type) ||
>>>>       !bch2_bucket_sectors_fragmented(ca, a))
>>>>   return 0;
>>>> --