Re: [PATCH] cifs: use cifsInodeInfo->open_file_lock while iterating to avoid a panic

[David Wysochanski <dwysocha@redhat.com>]

I'm ok with stable

On Thu, Oct 3, 2019 at 10:21 AM Steve French <smfrench@gmail.com> wrote:
>
> opinions on stable?   The patch it refers to was cc:stable 487317c99477
>
> On Thu, Oct 3, 2019 at 12:16 AM Ronnie Sahlberg <lsahlber@redhat.com> wrote:
> >
> > From: Dave Wysochanski <dwysocha@redhat.com>
> >
> > Commit 487317c99477 ("cifs: add spinlock for the openFileList to
> > cifsInodeInfo") added cifsInodeInfo->open_file_lock spin_lock to protect
> > the openFileList, but missed a few places where cifs_inode->openFileList
> > was enumerated.  Change these remaining tcon->open_file_lock to
> > cifsInodeInfo->open_file_lock to avoid panic in is_size_safe_to_change.
> >
> > [17313.245641] RIP: 0010:is_size_safe_to_change+0x57/0xb0 [cifs]
> > [17313.245645] Code: 68 40 48 89 ef e8 19 67 b7 f1 48 8b 43 40 48 8d 4b 40 48 8d 50 f0 48 39 c1 75 0f eb 47 48 8b 42 10 48 8d 50 f0 48 39 c1 74 3a <8b> 80 88 00 00 00 83 c0 01 a8 02 74 e6 48 89 ef c6 07 00 0f 1f 40
> > [17313.245649] RSP: 0018:ffff94ae1baefa30 EFLAGS: 00010202
> > [17313.245654] RAX: dead000000000100 RBX: ffff88dc72243300 RCX: ffff88dc72243340
> > [17313.245657] RDX: dead0000000000f0 RSI: 00000000098f7940 RDI: ffff88dd3102f040
> > [17313.245659] RBP: ffff88dd3102f040 R08: 0000000000000000 R09: ffff94ae1baefc40
> > [17313.245661] R10: ffffcdc8bb1c4e80 R11: ffffcdc8b50adb08 R12: 00000000098f7940
> > [17313.245663] R13: ffff88dc72243300 R14: ffff88dbc8f19600 R15: ffff88dc72243428
> > [17313.245667] FS:  00007fb145485700(0000) GS:ffff88dd3e000000(0000) knlGS:0000000000000000
> > [17313.245670] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [17313.245672] CR2: 0000026bb46c6000 CR3: 0000004edb110003 CR4: 00000000007606e0
> > [17313.245753] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > [17313.245756] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > [17313.245759] PKRU: 55555554
> > [17313.245761] Call Trace:
> > [17313.245803]  cifs_fattr_to_inode+0x16b/0x580 [cifs]
> > [17313.245838]  cifs_get_inode_info+0x35c/0xa60 [cifs]
> > [17313.245852]  ? kmem_cache_alloc_trace+0x151/0x1d0
> > [17313.245885]  cifs_open+0x38f/0x990 [cifs]
> > [17313.245921]  ? cifs_revalidate_dentry_attr+0x3e/0x350 [cifs]
> > [17313.245953]  ? cifsFileInfo_get+0x30/0x30 [cifs]
> > [17313.245960]  ? do_dentry_open+0x132/0x330
> > [17313.245963]  do_dentry_open+0x132/0x330
> > [17313.245969]  path_openat+0x573/0x14d0
> > [17313.245974]  do_filp_open+0x93/0x100
> > [17313.245979]  ? __check_object_size+0xa3/0x181
> > [17313.245986]  ? audit_alloc_name+0x7e/0xd0
> > [17313.245992]  do_sys_open+0x184/0x220
> > [17313.245999]  do_syscall_64+0x5b/0x1b0
> >
> > Fixes: 487317c99477 ("cifs: add spinlock for the openFileList to cifsInodeInfo")
> >
> > Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
> > Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
> > ---
> >  fs/cifs/file.c | 27 +++++++++++----------------
> >  1 file changed, 11 insertions(+), 16 deletions(-)
> >
> > diff --git a/fs/cifs/file.c b/fs/cifs/file.c
> > index 4b95700c507c..3758237bf951 100644
> > --- a/fs/cifs/file.c
> > +++ b/fs/cifs/file.c
> > @@ -1840,13 +1840,12 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
> >  {
> >         struct cifsFileInfo *open_file = NULL;
> >         struct cifs_sb_info *cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
> > -       struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
> >
> >         /* only filter by fsuid on multiuser mounts */
> >         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
> >                 fsuid_only = false;
> >
> > -       spin_lock(&tcon->open_file_lock);
> > +       spin_lock(&cifs_inode->open_file_lock);
> >         /* we could simply get the first_list_entry since write-only entries
> >            are always at the end of the list but since the first entry might
> >            have a close pending, we go through the whole list */
> > @@ -1858,7 +1857,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
> >                                 /* found a good file */
> >                                 /* lock it so it will not be closed on us */
> >                                 cifsFileInfo_get(open_file);
> > -                               spin_unlock(&tcon->open_file_lock);
> > +                               spin_unlock(&cifs_inode->open_file_lock);
> >                                 return open_file;
> >                         } /* else might as well continue, and look for
> >                              another, or simply have the caller reopen it
> > @@ -1866,7 +1865,7 @@ struct cifsFileInfo *find_readable_file(struct cifsInodeInfo *cifs_inode,
> >                 } else /* write only file */
> >                         break; /* write only files are last so must be done */
> >         }
> > -       spin_unlock(&tcon->open_file_lock);
> > +       spin_unlock(&cifs_inode->open_file_lock);
> >         return NULL;
> >  }
> >
> > @@ -1877,7 +1876,6 @@ cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only,
> >  {
> >         struct cifsFileInfo *open_file, *inv_file = NULL;
> >         struct cifs_sb_info *cifs_sb;
> > -       struct cifs_tcon *tcon;
> >         bool any_available = false;
> >         int rc = -EBADF;
> >         unsigned int refind = 0;
> > @@ -1897,16 +1895,15 @@ cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only,
> >         }
> >
> >         cifs_sb = CIFS_SB(cifs_inode->vfs_inode.i_sb);
> > -       tcon = cifs_sb_master_tcon(cifs_sb);
> >
> >         /* only filter by fsuid on multiuser mounts */
> >         if (!(cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER))
> >                 fsuid_only = false;
> >
> > -       spin_lock(&tcon->open_file_lock);
> > +       spin_lock(&cifs_inode->open_file_lock);
> >  refind_writable:
> >         if (refind > MAX_REOPEN_ATT) {
> > -               spin_unlock(&tcon->open_file_lock);
> > +               spin_unlock(&cifs_inode->open_file_lock);
> >                 return rc;
> >         }
> >         list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
> > @@ -1918,7 +1915,7 @@ cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only,
> >                         if (!open_file->invalidHandle) {
> >                                 /* found a good writable file */
> >                                 cifsFileInfo_get(open_file);
> > -                               spin_unlock(&tcon->open_file_lock);
> > +                               spin_unlock(&cifs_inode->open_file_lock);
> >                                 *ret_file = open_file;
> >                                 return 0;
> >                         } else {
> > @@ -1938,7 +1935,7 @@ cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only,
> >                 cifsFileInfo_get(inv_file);
> >         }
> >
> > -       spin_unlock(&tcon->open_file_lock);
> > +       spin_unlock(&cifs_inode->open_file_lock);
> >
> >         if (inv_file) {
> >                 rc = cifs_reopen_file(inv_file, false);
> > @@ -1953,7 +1950,7 @@ cifs_get_writable_file(struct cifsInodeInfo *cifs_inode, bool fsuid_only,
> >                 cifsFileInfo_put(inv_file);
> >                 ++refind;
> >                 inv_file = NULL;
> > -               spin_lock(&tcon->open_file_lock);
> > +               spin_lock(&cifs_inode->open_file_lock);
> >                 goto refind_writable;
> >         }
> >
> > @@ -4461,17 +4458,15 @@ static int cifs_readpage(struct file *file, struct page *page)
> >  static int is_inode_writable(struct cifsInodeInfo *cifs_inode)
> >  {
> >         struct cifsFileInfo *open_file;
> > -       struct cifs_tcon *tcon =
> > -               cifs_sb_master_tcon(CIFS_SB(cifs_inode->vfs_inode.i_sb));
> >
> > -       spin_lock(&tcon->open_file_lock);
> > +       spin_lock(&cifs_inode->open_file_lock);
> >         list_for_each_entry(open_file, &cifs_inode->openFileList, flist) {
> >                 if (OPEN_FMODE(open_file->f_flags) & FMODE_WRITE) {
> > -                       spin_unlock(&tcon->open_file_lock);
> > +                       spin_unlock(&cifs_inode->open_file_lock);
> >                         return 1;
> >                 }
> >         }
> > -       spin_unlock(&tcon->open_file_lock);
> > +       spin_unlock(&cifs_inode->open_file_lock);
> >         return 0;
> >  }
> >
> > --
> > 2.13.6
> >
>
>
> --
> Thanks,
>
> Steve



--
Dave Wysochanski
Principal Software Maintenance Engineer
T: 919-754-4024