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Message-ID: <06bea1c3fc9080b5798e6b5ad1ad533a145bf036.camel@ibm.com>
Date: Fri, 1 Aug 2025 18:26:31 +0000
From: Viacheslav Dubeyko <Slava.Dubeyko@....com>
To: "leocstone@...il.com" <leocstone@...il.com>,
"jack@...e.cz"
<jack@...e.cz>,
"penguin-kernel@...ove.SAKURA.ne.jp"
<penguin-kernel@...ove.SAKURA.ne.jp>,
"willy@...radead.org"
<willy@...radead.org>,
"brauner@...nel.org" <brauner@...nel.org>
CC: "glaubitz@...sik.fu-berlin.de" <glaubitz@...sik.fu-berlin.de>,
"frank.li@...o.com" <frank.li@...o.com>,
"slava@...eyko.com"
<slava@...eyko.com>,
"linux-fsdevel@...r.kernel.org"
<linux-fsdevel@...r.kernel.org>,
"linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>,
"akpm@...ux-foundation.org"
<akpm@...ux-foundation.org>
Subject: RE: [PATCH v4] hfs: update sanity check of the root record
On Fri, 2025-08-01 at 06:12 +0900, Tetsuo Handa wrote:
> On 2025/08/01 3:03, Viacheslav Dubeyko wrote:
> > On Thu, 2025-07-31 at 07:02 +0900, Tetsuo Handa wrote:
> > > On 2025/07/31 4:24, Viacheslav Dubeyko wrote:
> > > > If we considering case HFS_CDR_DIR in hfs_read_inode(), then we know that it
> > > > could be HFS_POR_CNID, HFS_ROOT_CNID, or >= HFS_FIRSTUSER_CNID. Do you mean that
> > > > HFS_POR_CNID could be a problem in hfs_write_inode()?
> > >
> > > Yes. Passing one of 1, 5 or 15 instead of 2 from hfs_fill_super() triggers BUG()
> > > in hfs_write_inode(). We *MUST* validate at hfs_fill_super(), or hfs_read_inode()
> > > shall have to also reject 1, 5 and 15 (and as a result only accept 2).
> >
> > The fix should be in hfs_read_inode(). Currently, suggested solution hides the
> > issue but not fix the problem.
>
> Not fixing this problem might be hiding other issues, by hitting BUG() before
> other issues shows up.
>
I am not going to start a philosophical discussion. We simply need to fix the
bug. The suggested patch doesn't fix the issue.
> > Because b-tree nodes could contain multiple
> > corrupted records. Now, this patch checks only record for root folder. Let's
> > imagine that root folder record will be OK but another record(s) will be
> > corrupted in such way.
>
> Can the inode number of the record retrieved as a result of
> hfs_cat_find_brec(HFS_ROOT_CNID) be something other than HFS_ROOT_CNID ?
>
> If the inode number of the record retrieved as a result of
> hfs_cat_find_brec(HFS_ROOT_CNID) must be HFS_ROOT_CNID, this patch itself will be
> a complete fix for this problem.
>
You are working with corrupted volume. In this case, you can extract any state
of the Catalog File's record.
> > Finally, we will have successful mount but operation with
> > corrupted record(s) will trigger this issue. So, I cannot consider this patch as
> > a complete fix of the problem.
>
> Did you try what you think as a fix of this problem (I guess something like
> shown below will be needed for avoid hitting BUG()) using
> https://lkml.kernel.org/r/a8f8da77-f099-499b-98e0-39ed159b6a2d@I-love.SAKURA.ne.jp ?
>
If you believe that you have another version of the patch, then simply send it
and I will review it. Sorry, I haven't enough time to discuss every movement of
your thoughts.
> diff --git a/fs/hfs/inode.c b/fs/hfs/inode.c
> index a81ce7a740b9..d60395111ed5 100644
> --- a/fs/hfs/inode.c
> +++ b/fs/hfs/inode.c
> @@ -81,7 +81,8 @@ static bool hfs_release_folio(struct folio *folio, gfp_t mask)
> tree = HFS_SB(sb)->cat_tree;
> break;
> default:
> - BUG();
> + pr_err("detected unknown inode %lu, running fsck.hfs is recommended.\n",
> + inode->i_ino);
> return false;
> }
>
> @@ -305,11 +306,31 @@ static int hfs_test_inode(struct inode *inode, void *data)
> case HFS_CDR_FIL:
> return inode->i_ino == be32_to_cpu(rec->file.FlNum);
> default:
> - BUG();
> + pr_err("detected unknown type %u, running fsck.hfs is recommended.\n", rec->type);
> return 1;
> }
> }
>
> +static bool is_bad_id(unsigned long ino)
> +{
> + switch (ino) {
> + case 0:
> + case 3:
> + case 4:
> + case 6:
> + case 7:
> + case 8:
> + case 9:
> + case 10:
> + case 11:
> + case 12:
> + case 13:
> + case 14:
> + return true;
> + }
> + return false;
> +}
Please, don't use hardcoded value. I already shared the point that we must use
the declared constants.
This function is incorrect and it cannot work for folders and files at the same
time.
Thanks,
Slava.
> +
> /*
> * hfs_read_inode
> */
> @@ -348,6 +369,10 @@ static int hfs_read_inode(struct inode *inode, void *data)
> }
>
> inode->i_ino = be32_to_cpu(rec->file.FlNum);
> + if (is_bad_id(inode->i_ino)) {
> + make_bad_inode(inode);
> + break;
> + }
> inode->i_mode = S_IRUGO | S_IXUGO;
> if (!(rec->file.Flags & HFS_FIL_LOCK))
> inode->i_mode |= S_IWUGO;
> @@ -358,9 +383,15 @@ static int hfs_read_inode(struct inode *inode, void *data)
> inode->i_op = &hfs_file_inode_operations;
> inode->i_fop = &hfs_file_operations;
> inode->i_mapping->a_ops = &hfs_aops;
> + if (inode->i_ino < 16)
> + pr_info("HFS_CDR_FIL i_ino=%ld\n", inode->i_ino);
> break;
> case HFS_CDR_DIR:
> inode->i_ino = be32_to_cpu(rec->dir.DirID);
> + if (is_bad_id(inode->i_ino)) {
> + make_bad_inode(inode);
> + break;
> + }
> inode->i_size = be16_to_cpu(rec->dir.Val) + 2;
> HFS_I(inode)->fs_blocks = 0;
> inode->i_mode = S_IFDIR | (S_IRWXUGO & ~hsb->s_dir_umask);
> @@ -368,6 +399,8 @@ static int hfs_read_inode(struct inode *inode, void *data)
> inode_set_atime_to_ts(inode, inode_set_ctime_to_ts(inode, hfs_m_to_utime(rec->dir.MdDat))));
> inode->i_op = &hfs_dir_inode_operations;
> inode->i_fop = &hfs_dir_operations;
> + if (inode->i_ino < 16)
> + pr_info("HFS_CDR_DIR i_ino=%ld\n", inode->i_ino);
> break;
> default:
> make_bad_inode(inode);
> @@ -441,7 +474,8 @@ int hfs_write_inode(struct inode *inode, struct writeback_control *wbc)
> hfs_btree_write(HFS_SB(inode->i_sb)->cat_tree);
> return 0;
> default:
> - BUG();
> + pr_err("detected unknown inode %lu, running fsck.hfs is recommended.\n",
> + inode->i_ino);
> return -EIO;
> }
> }
>
>
> # for i in $(seq 0 15); do timeout 1 unshare -m ./hfs $i; done
> # dmesg | grep fsck
> [ 52.563547] [ T479] hfs: detected unknown inode 1, running fsck.hfs is recommended.
> [ 56.606238] [ T255] hfs: detected unknown inode 5, running fsck.hfs is recommended.
> [ 66.694795] [ T500] hfs: detected unknown inode 15, running fsck.hfs is recommended.
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