releases/5.0.1/staging-erofs-fix-fast-symlink-w-o-xattr-when-fs-xattr-is-on.patch

   1 From 7077fffcb0b0b65dc75e341306aeef4d0e7f2ec6 Mon Sep 17 00:00:00 2001
   2 From: Gao Xiang <gaoxiang25@huawei.com>
   3 Date: Mon, 14 Jan 2019 19:40:23 +0800
   4 Subject: staging: erofs: fix fast symlink w/o xattr when fs xattr is on
   5
   6 From: Gao Xiang <gaoxiang25@huawei.com>
   7
   8 commit 7077fffcb0b0b65dc75e341306aeef4d0e7f2ec6 upstream.
   9
  10 Currently, this will hit a BUG_ON for these symlinks as follows:
  11
  12 - kernel message
  13 ------------[ cut here ]------------
  14 kernel BUG at drivers/staging/erofs/xattr.c:59!
  15 SMP PTI
  16 CPU: 1 PID: 1170 Comm: getllxattr Not tainted 4.20.0-rc6+ #92
  17 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-2.fc27 04/01/2014
  18 RIP: 0010:init_inode_xattrs+0x22b/0x270
  19 Code: 48 0f 45 ea f0 ff 4d 34 74 0d 41 83 4c 24 e0 01 31 c0 e9 00 fe ff ff 48 89 ef e8 e0 31 9e ff eb e9 89 e8 e9 ef fd ff ff 0f 0$
  20  <0f> 0b 48 89 ef e8 fb f6 9c ff 48 8b 45 08 a8 01 75 24 f0 ff 4d 34
  21 RSP: 0018:ffffa03ac026bdf8 EFLAGS: 00010246
  22 ------------[ cut here ]------------
  23 ...
  24 Call Trace:
  25  erofs_listxattr+0x30/0x2c0
  26  ? selinux_inode_listxattr+0x5a/0x80
  27  ? kmem_cache_alloc+0x33/0x170
  28  ? security_inode_listxattr+0x27/0x40
  29  listxattr+0xaf/0xc0
  30  path_listxattr+0x5a/0xa0
  31  do_syscall_64+0x43/0xf0
  32  entry_SYSCALL_64_after_hwframe+0x44/0xa9
  33 ...
  34 ---[ end trace 3c24b49408dc0c72 ]---
  35
  36 Fix it by checking ->xattr_isize in init_inode_xattrs(),
  37 and it also fixes improper return value -ENOTSUPP
  38 (it should be -ENODATA if xattr is enabled) for those inodes.
  39
  40 Fixes: b17500a0fdba ("staging: erofs: introduce xattr & acl support")
  41 Cc: <stable@vger.kernel.org> # 4.19+
  42 Reported-by: Li Guifu <bluce.liguifu@huawei.com>
  43 Tested-by: Li Guifu <bluce.liguifu@huawei.com>
  44 Reviewed-by: Chao Yu <yuchao0@huawei.com>
  45 Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
  46 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  47
  48 ---
  49  drivers/staging/erofs/inode.c |    8 ++++----
  50  drivers/staging/erofs/xattr.c |   25 ++++++++++++++++++++-----
  51  2 files changed, 24 insertions(+), 9 deletions(-)
  52
  53 --- a/drivers/staging/erofs/inode.c
  54 +++ b/drivers/staging/erofs/inode.c
  55 @@ -185,16 +185,16 @@ static int fill_inode(struct inode *inod
  56                 /* setup the new inode */
  57                 if (S_ISREG(inode->i_mode)) {
  58  #ifdef CONFIG_EROFS_FS_XATTR
  59 -                       if (vi->xattr_isize)
  60 -                               inode->i_op = &erofs_generic_xattr_iops;
  61 +                       inode->i_op = &erofs_generic_xattr_iops;
  62  #endif
  63                         inode->i_fop = &generic_ro_fops;
  64                 } else if (S_ISDIR(inode->i_mode)) {
  65                         inode->i_op =
  66  #ifdef CONFIG_EROFS_FS_XATTR
  67 -                               vi->xattr_isize ? &erofs_dir_xattr_iops :
  68 -#endif
  69 +                               &erofs_dir_xattr_iops;
  70 +#else
  71                                 &erofs_dir_iops;
  72 +#endif
  73                         inode->i_fop = &erofs_dir_fops;
  74                 } else if (S_ISLNK(inode->i_mode)) {
  75                         /* by default, page_get_link is used for symlink */
  76 --- a/drivers/staging/erofs/xattr.c
  77 +++ b/drivers/staging/erofs/xattr.c
  78 @@ -56,7 +56,26 @@ static int init_inode_xattrs(struct inod
  79                 return 0;
  80
  81         vi = EROFS_V(inode);
  82 -       BUG_ON(!vi->xattr_isize);
  83 +
  84 +       /*
  85 +        * bypass all xattr operations if ->xattr_isize is not greater than
  86 +        * sizeof(struct erofs_xattr_ibody_header), in detail:
  87 +        * 1) it is not enough to contain erofs_xattr_ibody_header then
  88 +        *    ->xattr_isize should be 0 (it means no xattr);
  89 +        * 2) it is just to contain erofs_xattr_ibody_header, which is on-disk
  90 +        *    undefined right now (maybe use later with some new sb feature).
  91 +        */
  92 +       if (vi->xattr_isize == sizeof(struct erofs_xattr_ibody_header)) {
  93 +               errln("xattr_isize %d of nid %llu is not supported yet",
  94 +                     vi->xattr_isize, vi->nid);
  95 +               return -ENOTSUPP;
  96 +       } else if (vi->xattr_isize < sizeof(struct erofs_xattr_ibody_header)) {
  97 +               if (unlikely(vi->xattr_isize)) {
  98 +                       DBG_BUGON(1);
  99 +                       return -EIO;    /* xattr ondisk layout error */
 100 +               }
 101 +               return -ENOATTR;
 102 +       }
 103
 104         sb = inode->i_sb;
 105         sbi = EROFS_SB(sb);
 106 @@ -422,7 +441,6 @@ static int erofs_xattr_generic_get(const
 107                 struct dentry *unused, struct inode *inode,
 108                 const char *name, void *buffer, size_t size)
 109  {
 110 -       struct erofs_vnode *const vi = EROFS_V(inode);
 111         struct erofs_sb_info *const sbi = EROFS_I_SB(inode);
 112
 113         switch (handler->flags) {
 114 @@ -440,9 +458,6 @@ static int erofs_xattr_generic_get(const
 115                 return -EINVAL;
 116         }
 117
 118 -       if (!vi->xattr_isize)
 119 -               return -ENOATTR;
 120 -
 121         return erofs_getxattr(inode, handler->flags, name, buffer, size);
 122  }
 123