Re: [PATCH] f2fs: fix to avoid accessing uninitialized field of inode page in is_alive()

[Jaegeuk Kim]

On 09/09, Chao Yu wrote:
> On 2019/9/9 17:33, Jaegeuk Kim wrote:
> > On 09/09, Chao Yu wrote:
> >> On 2019/9/9 16:37, Jaegeuk Kim wrote:
> >>> On 09/09, Chao Yu wrote:
> >>>> On 2019/9/9 15:58, Chao Yu wrote:
> >>>>> On 2019/9/9 15:44, Jaegeuk Kim wrote:
> >>>>>> On 09/07, Chao Yu wrote:
> >>>>>>> On 2019-9-7 7:48, Jaegeuk Kim wrote:
> >>>>>>>> On 09/06, Chao Yu wrote:
> >>>>>>>>> If inode is newly created, inode page may not synchronize with inode cache,
> >>>>>>>>> so fields like .i_inline or .i_extra_isize could be wrong, in below call
> >>>>>>>>> path, we may access such wrong fields, result in failing to migrate valid
> >>>>>>>>> target block.
> >>>>>>>>
> >>>>>>>> If data is valid, how can we get new inode page?
> >>>>>>
> >>>>>> Let me rephrase the question. If inode is newly created, is this data block
> >>>>>> really valid to move in GC?
> >>>>>
> >>>>> I guess it's valid, let double check that.
> >>>>
> >>>> We can see inode page:
> >>>>
> >>>> - f2fs_create
> >>>>  - f2fs_add_link
> >>>>   - f2fs_add_dentry
> >>>>    - f2fs_init_inode_metadata
> >>>>     - f2fs_add_inline_entry
> >>>>      - ipage = f2fs_new_inode_page
> >>>>      - f2fs_put_page(ipage)   <---- after this
> >>>
> >>> Can you print out how many block was assigned to this inode?

Can we update inode before finally putting ipage?

> >>
> >> Add log like this:
> >>
> >> 		if (!test_and_set_bit(segno, SIT_I(sbi)->invalid_segmap)) {
> >> 			if (is_inode) {
> >> 				for (i = 0; i < 923 - 50; i++) {
> >> 					__le32 *base = blkaddr_in_node(node);
> >> 					unsigned ofs = offset_in_addr(inode);
> >>
> >> 					printk("i:%u, addr:%x\n", i,
> >> 						le32_to_cpu(*(base + i)));
> >> 				}
> >> 				printk("i_inline: %u\n", inode->i_inline);
> >> 			}
> >>
> >> It shows:
> >> ...
> >> i:10, addr:e66a
> >> ...
> >> i:46, addr:e66c
> >> i:47, addr:e66d
> >> i:48, addr:e66e
> >> i:49, addr:e66f
> >> i:50, addr:e670
> >> i:51, addr:e671
> >> i:52, addr:e672
> >> i:53, addr:e673
> >> i:54, addr:e674
> >> i:55, addr:e675
> >> i:56, addr:e676
> >> ...
> >> i:140, addr:2c35    <--- we want to migrate this block, however, without correct
> >> .i_inline and .i_extra_isize value, we can just find i_addr[i:140-6] = NULL_ADDR
> > 
> > So, the theory is the block is indeed valid and the address was updated before
> > write_inode()?
> 
> I guess so. :)
> 
> Thanks,
> 
> > 
> >> i:141, addr:2c38
> >> i:142, addr:2c39
> >> i:143, addr:2c3b
> >> i:144, addr:2c3e
> >> i:145, addr:2c40
> >> i:146, addr:2c44
> >> i:147, addr:2c48
> >> i:148, addr:2c4a
> >> i:149, addr:2c4c
> >> i:150, addr:2c4f
> >> i:151, addr:2c59
> >> i:152, addr:2c5d
> >> ...
> >> i:188, addr:e677
> >> i:189, addr:e678
> >> i:190, addr:e679
> >> i:191, addr:e67a
> >> i:192, addr:e67b
> >> i:193, addr:e67c
> >> i:194, addr:e67d
> >> i:195, addr:e67e
> >> i:196, addr:e67f
> >> i:197, addr:e680
> >> i:198, addr:ffffffff
> >> i:199, addr:ffffffff
> >> i:200, addr:ffffffff
> >> i:201, addr:ffffffff
> >> i:202, addr:ffffffff
> >> i:203, addr:ffffffff
> >> i:204, addr:ffffffff
> >> i:205, addr:ffffffff
> >> i:206, addr:ffffffff
> >> i:207, addr:ffffffff
> >> i:208, addr:ffffffff
> >> i:209, addr:ffffffff
> >> i:210, addr:ffffffff
> >> i:211, addr:ffffffff
> >> i:212, addr:ffffffff
> >> i:213, addr:ffffffff
> >> i:214, addr:ffffffff
> >> i:215, addr:ffffffff
> >> i:216, addr:ffffffff
> >> i:217, addr:ffffffff
> >> i:218, addr:ffffffff
> >> i:219, addr:ffffffff
> >> i:220, addr:ffffffff
> >> i:221, addr:ffffffff
> >> i:222, addr:ffffffff
> >> i:223, addr:ffffffff
> >> i:224, addr:ffffffff
> >> i:225, addr:ffffffff
> >> i:226, addr:ffffffff
> >> i:227, addr:ffffffff
> >> i:228, addr:ffffffff
> >> i:229, addr:ffffffff
> >> i:230, addr:ffffffff
> >> i:231, addr:ffffffff
> >> i:232, addr:ffffffff
> >> i:233, addr:ffffffff
> >> i:234, addr:b032
> >> i:235, addr:b033
> >> i:236, addr:b034
> >> i:237, addr:b035
> >> i:238, addr:b036
> >> i:239, addr:b038
> >> ...
> >> i:283, addr:e681
> >> ...
> >> i_inline: 0
> >>
> >> F2FS-fs (zram1): summary nid: 360, ofs: 134, ver: 0
> >> F2FS-fs (zram1): blkaddr 2c35 (blkaddr in node 0) <-blkaddr in node is NULL_ADDR
> >> F2FS-fs (zram1): expect: seg 14, ofs_in_seg: 53
> >> F2FS-fs (zram1): real: seg 4294967295, ofs_in_seg: 0
> >> F2FS-fs (zram1): ofs: 53, 0
> >> F2FS-fs (zram1): node info ino:360, nid:360, nofs:0
> >> F2FS-fs (zram1): ofs_in_addr: 0
> >> F2FS-fs (zram1): end ========
> >>
> >>>
> >>>>
> >>>>>
> >>>>>>
> >>>>>>>
> >>>>>>> is_alive()
> >>>>>>> {
> >>>>>>> ...
> >>>>>>> 	node_page = f2fs_get_node_page(sbi, nid);  <--- inode page
> >>>>>>
> >>>>>> Aren't we seeing the below version warnings?
> >>>>>>
> >>>>>> if (sum->version != dni->version) {
> >>>>>> 	f2fs_warn(sbi, "%s: valid data with mismatched node version.",
> >>>>>>                            __func__);
> >>>>>>         set_sbi_flag(sbi, SBI_NEED_FSCK);
> >>>>>> }
> >>>>
> >>>> The version of summary and dni are all zero.
> >>>
> >>> Then, this node was allocated and removed without being flushed.
> >>>
> >>>>
> >>>> summary nid: 613, ofs: 111, ver: 0
> >>>> blkaddr 2436 (blkaddr in node 0)
> >>>> expect: seg 10, ofs_in_seg: 54
> >>>> real: seg 4294967295, ofs_in_seg: 0
> >>>> ofs: 54, 0
> >>>> node info ino:613, nid:613, nofs:0
> >>>> ofs_in_addr: 0
> >>>>
> >>>> Thanks,
> >>>>
> >>>>>>
> >>>>>>>
> >>>>>>> 	source_blkaddr = datablock_addr(NULL, node_page, ofs_in_node);
> >>>>>>
> >>>>>> So, we're getting this? Does this incur infinite loop in GC?
> >>>>>>
> >>>>>> if (!test_and_set_bit(segno, SIT_I(sbi)->invalid_segmap)) {
> >>>>>> 	f2fs_err(sbi, "mismatched blkaddr %u (source_blkaddr %u) in seg %u\n",
> >>>>>> 	f2fs_bug_on(sbi, 1);
> >>>>>> }
> >>>>>
> >>>>> Yes, I only get this with generic/269, rather than "valid data with mismatched
> >>>>> node version.".
> >>>
> >>> Was this block moved as valid? In either way, is_alive() returns false, no?
> >>> How about checking i_blocks to detect the page is initialized in is_alive()?
> >>>
> >>>>>
> >>>>> With this patch, generic/269 won't panic again.
> >>>>>
> >>>>> Thanks,
> >>>>>
> >>>>>>
> >>>>>>> ...
> >>>>>>> }
> >>>>>>>
> >>>>>>> datablock_addr()
> >>>>>>> {
> >>>>>>> ...
> >>>>>>> 	base = offset_in_addr(&raw_node->i);  <--- the base could be wrong here due to
> >>>>>>> accessing uninitialized .i_inline of raw_node->i.
> >>>>>>> ...
> >>>>>>> }
> >>>>>>>
> >>>>>>> Thanks,
> >>>>>>>
> >>>>>>>>
> >>>>>>>>>
> >>>>>>>>> - gc_data_segment
> >>>>>>>>>  - is_alive
> >>>>>>>>>   - datablock_addr
> >>>>>>>>>    - offset_in_addr
> >>>>>>>>>
> >>>>>>>>> Fixes: 7a2af766af15 ("f2fs: enhance on-disk inode structure scalability")
> >>>>>>>>> Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx>
> >>>>>>>>> ---
> >>>>>>>>>  fs/f2fs/dir.c | 3 +++
> >>>>>>>>>  1 file changed, 3 insertions(+)
> >>>>>>>>>
> >>>>>>>>> diff --git a/fs/f2fs/dir.c b/fs/f2fs/dir.c
> >>>>>>>>> index 765f13354d3f..b1840852967e 100644
> >>>>>>>>> --- a/fs/f2fs/dir.c
> >>>>>>>>> +++ b/fs/f2fs/dir.c
> >>>>>>>>> @@ -479,6 +479,9 @@ struct page *f2fs_init_inode_metadata(struct inode *inode, struct inode *dir,
> >>>>>>>>>  		if (IS_ERR(page))
> >>>>>>>>>  			return page;
> >>>>>>>>>  
> >>>>>>>>> +		/* synchronize inode page's data from inode cache */
> >>>>>>>>> +		f2fs_update_inode(inode, page);
> >>>>>>>>> +
> >>>>>>>>>  		if (S_ISDIR(inode->i_mode)) {
> >>>>>>>>>  			/* in order to handle error case */
> >>>>>>>>>  			get_page(page);
> >>>>>>>>> -- 
> >>>>>>>>> 2.18.0.rc1
> >>>>>> .
> >>>>>>
> >>> .
> >>>
> > .
> >