2020-03-25 09:19:48

by Chao Yu

Subject: [PATCH v2 3/5] f2fs: fix to avoid NULL pointer dereference

Unable to handle kernel NULL pointer dereference at virtual address 00000000
PC is at f2fs_free_dic+0x60/0x2c8
LR is at f2fs_decompress_pages+0x3c4/0x3e8
f2fs_free_dic+0x60/0x2c8
f2fs_decompress_pages+0x3c4/0x3e8
__read_end_io+0x78/0x19c
f2fs_post_read_work+0x6c/0x94
process_one_work+0x210/0x48c
worker_thread+0x2e8/0x44c
kthread+0x110/0x120
ret_from_fork+0x10/0x18

In f2fs_free_dic(), we can not use f2fs_put_page(,1) to release dic->tpages[i],
as the page's mapping is NULL.

Signed-off-by: Chao Yu <[email protected]>
---
v2:
- fix to skip release tpages[i] if it is NULL in error path.
fs/f2fs/compress.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index ef7dd04312fe..6e10800729b6 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1137,7 +1137,10 @@ void f2fs_free_dic(struct decompress_io_ctx *dic)
for (i = 0; i < dic->cluster_size; i++) {
if (dic->rpages[i])
continue;
- f2fs_put_page(dic->tpages[i], 1);
+ if (!dic->tpages[i])
+ continue;
+ unlock_page(dic->tpages[i]);
+ put_page(dic->tpages[i]);
}
kfree(dic->tpages);
}
--
2.18.0.rc1

2020-03-25 15:50:47

by Jaegeuk Kim

Subject: Re: [PATCH v2 3/5] f2fs: fix to avoid NULL pointer dereference

Hi Chao,

I don't want to rebase old commit at this moment, so applied on top of the tree.

Thanks,

On 03/25, Chao Yu wrote:
> Unable to handle kernel NULL pointer dereference at virtual address 00000000
> PC is at f2fs_free_dic+0x60/0x2c8
> LR is at f2fs_decompress_pages+0x3c4/0x3e8
> f2fs_free_dic+0x60/0x2c8
> f2fs_decompress_pages+0x3c4/0x3e8
> __read_end_io+0x78/0x19c
> f2fs_post_read_work+0x6c/0x94
> process_one_work+0x210/0x48c
> worker_thread+0x2e8/0x44c
> kthread+0x110/0x120
> ret_from_fork+0x10/0x18
>
> In f2fs_free_dic(), we can not use f2fs_put_page(,1) to release dic->tpages[i],
> as the page's mapping is NULL.
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> v2:
> - fix to skip release tpages[i] if it is NULL in error path.
> fs/f2fs/compress.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index ef7dd04312fe..6e10800729b6 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -1137,7 +1137,10 @@ void f2fs_free_dic(struct decompress_io_ctx *dic)
> for (i = 0; i < dic->cluster_size; i++) {
> if (dic->rpages[i])
> continue;
> - f2fs_put_page(dic->tpages[i], 1);
> + if (!dic->tpages[i])
> + continue;
> + unlock_page(dic->tpages[i]);
> + put_page(dic->tpages[i]);
> }
> kfree(dic->tpages);
> }
> --
> 2.18.0.rc1

2020-03-26 09:31:19

by Chao Yu

Subject: Re: [PATCH v2 3/5] f2fs: fix to avoid NULL pointer dereference

Hi Jaegeuk,

I've made that diff as a patch and changed title and commit message a
bit, let's merge the new one.

Thanks,

On 2020/3/25 23:50, Jaegeuk Kim wrote:
> Hi Chao,
>
> I don't want to rebase old commit at this moment, so applied on top of the tree.
>
> Thanks,
>
> On 03/25, Chao Yu wrote:
>> Unable to handle kernel NULL pointer dereference at virtual address 00000000
>> PC is at f2fs_free_dic+0x60/0x2c8
>> LR is at f2fs_decompress_pages+0x3c4/0x3e8
>> f2fs_free_dic+0x60/0x2c8
>> f2fs_decompress_pages+0x3c4/0x3e8
>> __read_end_io+0x78/0x19c
>> f2fs_post_read_work+0x6c/0x94
>> process_one_work+0x210/0x48c
>> worker_thread+0x2e8/0x44c
>> kthread+0x110/0x120
>> ret_from_fork+0x10/0x18
>>
>> In f2fs_free_dic(), we can not use f2fs_put_page(,1) to release dic->tpages[i],
>> as the page's mapping is NULL.
>>
>> Signed-off-by: Chao Yu <[email protected]>
>> ---
>> v2:
>> - fix to skip release tpages[i] if it is NULL in error path.
>> fs/f2fs/compress.c | 5 ++++-
>> 1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
>> index ef7dd04312fe..6e10800729b6 100644
>> --- a/fs/f2fs/compress.c
>> +++ b/fs/f2fs/compress.c
>> @@ -1137,7 +1137,10 @@ void f2fs_free_dic(struct decompress_io_ctx *dic)
>> for (i = 0; i < dic->cluster_size; i++) {
>> if (dic->rpages[i])
>> continue;
>> - f2fs_put_page(dic->tpages[i], 1);
>> + if (!dic->tpages[i])
>> + continue;
>> + unlock_page(dic->tpages[i]);
>> + put_page(dic->tpages[i]);
>> }
>> kfree(dic->tpages);
>> }
>> --
>> 2.18.0.rc1
> .
>