On Fri, Nov 26, 2021 at 09:54:56AM +0800, yangerkun wrote:
> Cc ntfs3:
>
> Maybe it's a problem like this:
>
> do_new_mount
> fs_context_for_mount
> alloc_fs_context
> ntfs_init_fs_context
> sbi = kzalloc(sizeof(struct ntfs_sb_info), GFP_NOFS);
> fc->s_fs_info = sbi;
> vfs_get_tree
> ntfs_fs_get_tree
> get_tree_bdev
> blkdev_get_by_path // return error and sbi->sb will be NULL
> put_fs_context
> ntfs_fs_free
> put_ntfs
> ntfs_update_mftmirr
> struct super_block *sb = sbi->sb; // NULL
> u32 blocksize = sb->s_blocksize; // BOOM
>
> It's actually a ntfs3 bug which may be introduced by:
>
> 610f8f5a7baf fs/ntfs3: Use new api for mounting
Yeap. Thank you very much. Will send patch for this in within 24h.
> On 2021/11/26 2:03, Linus Torvalds wrote:
> > On Thu, Nov 25, 2021 at 6:08 AM kernel test robot <oliver.sang@xxxxxxxxx> wrote:
> > > FYI, we noticed the following commit (built with clang-14):
> > >
> > > commit: 0858d7da8a09e440fb192a0239d20249a2d16af8 ("ramfs: fix mount source show for ramfs")
> >
> > Funky. That commit seems to have nothing to do with the oops:
> >
> > > [ 806.257788][ T204] /dev/root: Can't open blockdev
> > > [ 806.259101][ T204] general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] SMP KASAN
> > > [ 806.263082][ T204] KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
> >
> > Not a very helpful error message,a nd the KASAN comment makes little sense, but
> >
> > > [ 806.267540][ T204] RIP: 0010:ntfs_update_mftmirr (kbuild/src/consumer/fs/ntfs3/fsntfs.c:834)
> >
> > That's
> >
> > u32 blocksize = sb->s_blocksize;
> >
> > and presumably with KASAN you end up getting hat odd 0xdffffc0000000003 thing.
> >
> > Anyway, looks like sb is NULL, and the code is
> >
> > int ntfs_update_mftmirr(struct ntfs_sb_info *sbi, int wait)
> > {
> > int err;
> > struct super_block *sb = sbi->sb;
> > u32 blocksize = sb->s_blocksize;
> > sector_t block1, block2;
> >
> > although I have no idea how sbi->sb could be NULL.
> >
> > Konstantin? See
> >
> > https://lore.kernel.org/lkml/20211125140816.GC3109@xsang-OptiPlex-9020/
> >
> > for the full thing.
> >
> > Linus
> > .
> >
