* [PATCH v2] f2fs: avoid out-of-range memory access
@ 2019-07-02 8:05 Ocean Chen
2019-07-03 2:07 ` Chao Yu
0 siblings, 1 reply; 5+ messages in thread
From: Ocean Chen @ 2019-07-02 8:05 UTC (permalink / raw)
To: jaegeuk, yuchao0, linux-f2fs-devel, linux-kernel; +Cc: oceanchen
blk_off might over 512 due to fs corrupt.
Use ENTRIES_IN_SUM to protect invalid memory access.
v2:
- fix typo
Signed-off-by: Ocean Chen <oceanchen@google.com>
---
fs/f2fs/segment.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8dee063c833f..a5e8af0bd62e 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3403,6 +3403,8 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
for (j = 0; j < blk_off; j++) {
struct f2fs_summary *s;
+ if (j >= ENTRIES_IN_SUM)
+ return -EFAULT;
s = (struct f2fs_summary *)(kaddr + offset);
seg_i->sum_blk->entries[j] = *s;
offset += SUMMARY_SIZE;
--
2.22.0.410.gd8fdbe21b5-goog
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH v2] f2fs: avoid out-of-range memory access
2019-07-02 8:05 [PATCH v2] f2fs: avoid out-of-range memory access Ocean Chen
@ 2019-07-03 2:07 ` Chao Yu
2019-07-03 15:03 ` Ocean Chen
0 siblings, 1 reply; 5+ messages in thread
From: Chao Yu @ 2019-07-03 2:07 UTC (permalink / raw)
To: Ocean Chen, jaegeuk, linux-f2fs-devel, linux-kernel
Hi Ocean,
If filesystem is corrupted, it should fail mount due to below check in
f2fs_sanity_check_ckpt(), so we are safe in read_compacted_summaries() to access
entries[0,blk_off], right?
for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) {
if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs ||
le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg)
return 1;
Thanks,
On 2019/7/2 16:05, Ocean Chen wrote:
> blk_off might over 512 due to fs corrupt.
> Use ENTRIES_IN_SUM to protect invalid memory access.
>
> v2:
> - fix typo
> Signed-off-by: Ocean Chen <oceanchen@google.com>
> ---
> fs/f2fs/segment.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> index 8dee063c833f..a5e8af0bd62e 100644
> --- a/fs/f2fs/segment.c
> +++ b/fs/f2fs/segment.c
> @@ -3403,6 +3403,8 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
>
> for (j = 0; j < blk_off; j++) {
> struct f2fs_summary *s;
> + if (j >= ENTRIES_IN_SUM)
> + return -EFAULT;
> s = (struct f2fs_summary *)(kaddr + offset);
> seg_i->sum_blk->entries[j] = *s;
> offset += SUMMARY_SIZE;
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] f2fs: avoid out-of-range memory access
2019-07-03 2:07 ` Chao Yu
@ 2019-07-03 15:03 ` Ocean Chen
2019-07-04 7:11 ` Chao Yu
0 siblings, 1 reply; 5+ messages in thread
From: Ocean Chen @ 2019-07-03 15:03 UTC (permalink / raw)
To: yuchao0, jaegeuk, linux-f2fs-devel, linux-kernel
Hi Yu Chao,
The cur_data_segno only was checked in mount process. In terms of
security concern, it's better to check value before using it. I know the
risk is low. IMHO, it can be safer.
BTW, I found we can only check blk_off before for loop instead of
checking 'j' in each iteratoin.
On Wed, Jul 03, 2019 at 10:07:11AM +0800, Chao Yu wrote:
> Hi Ocean,
>
> If filesystem is corrupted, it should fail mount due to below check in
> f2fs_sanity_check_ckpt(), so we are safe in read_compacted_summaries() to access
> entries[0,blk_off], right?
>
> for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) {
> if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs ||
> le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg)
> return 1;
>
> Thanks,
>
> On 2019/7/2 16:05, Ocean Chen wrote:
> > blk_off might over 512 due to fs corrupt.
> > Use ENTRIES_IN_SUM to protect invalid memory access.
> >
> > v2:
> > - fix typo
> > Signed-off-by: Ocean Chen <oceanchen@google.com>
> > ---
> > fs/f2fs/segment.c | 2 ++
> > 1 file changed, 2 insertions(+)
> >
> > diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> > index 8dee063c833f..a5e8af0bd62e 100644
> > --- a/fs/f2fs/segment.c
> > +++ b/fs/f2fs/segment.c
> > @@ -3403,6 +3403,8 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
> >
> > for (j = 0; j < blk_off; j++) {
> > struct f2fs_summary *s;
> > + if (j >= ENTRIES_IN_SUM)
> > + return -EFAULT;
> > s = (struct f2fs_summary *)(kaddr + offset);
> > seg_i->sum_blk->entries[j] = *s;
> > offset += SUMMARY_SIZE;
> >
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] f2fs: avoid out-of-range memory access
2019-07-03 15:03 ` Ocean Chen
@ 2019-07-04 7:11 ` Chao Yu
2019-07-08 3:21 ` Ocean Chen
0 siblings, 1 reply; 5+ messages in thread
From: Chao Yu @ 2019-07-04 7:11 UTC (permalink / raw)
To: Ocean Chen, jaegeuk, linux-f2fs-devel, linux-kernel
Hi Ocean,
On 2019/7/3 23:03, Ocean Chen wrote:
> Hi Yu Chao,
>
> The cur_data_segno only was checked in mount process. In terms of
> security concern, it's better to check value before using it. I know the
Could you explain more about security concern.. Do you get any report from user
or tools that complaining f2fs issue/codes?
I'm not against sanity check for basic core data of filesystem in run-time, but,
in order to troubleshoot root cause of this issue we can trigger panic directly
to dump more info under F2FS_CHECK_FS macro.
So, maybe we can change as below?
blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
+if (blk_off > ENTRIES_IN_SUM) {
+ f2fs_bug_on(1);
+ f2fs_put_page(page, 1);
+ return -EFAULT;
+}
Thanks,
> risk is low. IMHO, it can be safer.
> BTW, I found we can only check blk_off before for loop instead of
> checking 'j' in each iteratoin.
>
> On Wed, Jul 03, 2019 at 10:07:11AM +0800, Chao Yu wrote:
>> Hi Ocean,
>>
>> If filesystem is corrupted, it should fail mount due to below check in
>> f2fs_sanity_check_ckpt(), so we are safe in read_compacted_summaries() to access
>> entries[0,blk_off], right?
>>
>> for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) {
>> if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs ||
>> le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg)
>> return 1;
>>
>> Thanks,
>>
>> On 2019/7/2 16:05, Ocean Chen wrote:
>>> blk_off might over 512 due to fs corrupt.
>>> Use ENTRIES_IN_SUM to protect invalid memory access.
>>>
>>> v2:
>>> - fix typo
>>> Signed-off-by: Ocean Chen <oceanchen@google.com>
>>> ---
>>> fs/f2fs/segment.c | 2 ++
>>> 1 file changed, 2 insertions(+)
>>>
>>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
>>> index 8dee063c833f..a5e8af0bd62e 100644
>>> --- a/fs/f2fs/segment.c
>>> +++ b/fs/f2fs/segment.c
>>> @@ -3403,6 +3403,8 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
>>>
>>> for (j = 0; j < blk_off; j++) {
>>> struct f2fs_summary *s;
>>> + if (j >= ENTRIES_IN_SUM)
>>> + return -EFAULT;
>>> s = (struct f2fs_summary *)(kaddr + offset);
>>> seg_i->sum_blk->entries[j] = *s;
>>> offset += SUMMARY_SIZE;
>>>
> .
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH v2] f2fs: avoid out-of-range memory access
2019-07-04 7:11 ` Chao Yu
@ 2019-07-08 3:21 ` Ocean Chen
0 siblings, 0 replies; 5+ messages in thread
From: Ocean Chen @ 2019-07-08 3:21 UTC (permalink / raw)
To: yuchao0, jaegeuk, linux-f2fs-devel, linux-kernel
Hi YuChao,
Yes, we got externel researcher reports this security vulnerability.
And dump info is better when blk_off is invalid. I'll prepare the next
patch for it.
On Thu, Jul 04, 2019 at 03:11:27PM +0800, Chao Yu wrote:
> Hi Ocean,
>
> On 2019/7/3 23:03, Ocean Chen wrote:
> > Hi Yu Chao,
> >
> > The cur_data_segno only was checked in mount process. In terms of
> > security concern, it's better to check value before using it. I know the
>
> Could you explain more about security concern.. Do you get any report from user
> or tools that complaining f2fs issue/codes?
>
> I'm not against sanity check for basic core data of filesystem in run-time, but,
> in order to troubleshoot root cause of this issue we can trigger panic directly
> to dump more info under F2FS_CHECK_FS macro.
>
> So, maybe we can change as below?
>
> blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
> +if (blk_off > ENTRIES_IN_SUM) {
> + f2fs_bug_on(1);
> + f2fs_put_page(page, 1);
> + return -EFAULT;
> +}
>
> Thanks,
>
> > risk is low. IMHO, it can be safer.
> > BTW, I found we can only check blk_off before for loop instead of
> > checking 'j' in each iteratoin.
> >
> > On Wed, Jul 03, 2019 at 10:07:11AM +0800, Chao Yu wrote:
> >> Hi Ocean,
> >>
> >> If filesystem is corrupted, it should fail mount due to below check in
> >> f2fs_sanity_check_ckpt(), so we are safe in read_compacted_summaries() to access
> >> entries[0,blk_off], right?
> >>
> >> for (i = 0; i < NR_CURSEG_DATA_TYPE; i++) {
> >> if (le32_to_cpu(ckpt->cur_data_segno[i]) >= main_segs ||
> >> le16_to_cpu(ckpt->cur_data_blkoff[i]) >= blocks_per_seg)
> >> return 1;
> >>
> >> Thanks,
> >>
> >> On 2019/7/2 16:05, Ocean Chen wrote:
> >>> blk_off might over 512 due to fs corrupt.
> >>> Use ENTRIES_IN_SUM to protect invalid memory access.
> >>>
> >>> v2:
> >>> - fix typo
> >>> Signed-off-by: Ocean Chen <oceanchen@google.com>
> >>> ---
> >>> fs/f2fs/segment.c | 2 ++
> >>> 1 file changed, 2 insertions(+)
> >>>
> >>> diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
> >>> index 8dee063c833f..a5e8af0bd62e 100644
> >>> --- a/fs/f2fs/segment.c
> >>> +++ b/fs/f2fs/segment.c
> >>> @@ -3403,6 +3403,8 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
> >>>
> >>> for (j = 0; j < blk_off; j++) {
> >>> struct f2fs_summary *s;
> >>> + if (j >= ENTRIES_IN_SUM)
> >>> + return -EFAULT;
> >>> s = (struct f2fs_summary *)(kaddr + offset);
> >>> seg_i->sum_blk->entries[j] = *s;
> >>> offset += SUMMARY_SIZE;
> >>>
> > .
> >
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2019-07-08 3:21 UTC | newest]
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2019-07-02 8:05 [PATCH v2] f2fs: avoid out-of-range memory access Ocean Chen
2019-07-03 2:07 ` Chao Yu
2019-07-03 15:03 ` Ocean Chen
2019-07-04 7:11 ` Chao Yu
2019-07-08 3:21 ` Ocean Chen
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