linux-stable.git/fs, branch v4.4.284 Linux kernel stable tree cifs: fix wrong release in sess_alloc_buffer() failed path 2021-09-22T09:41:26+00:00 Ding Hui dinghui@sangfor.com.cn 2021-08-17T14:55:10+00:00 d4a127e2a11650ead18d0307268dbe3c9a687468 [ Upstream commit d72c74197b70bc3c95152f351a568007bffa3e11 ] smb_buf is allocated by small_smb_init_no_tc(), and buf type is CIFS_SMALL_BUFFER, so we should use cifs_small_buf_release() to release it in failed path. Signed-off-by: Ding Hui <dinghui@sangfor.com.cn> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d72c74197b70bc3c95152f351a568007bffa3e11 ]

smb_buf is allocated by small_smb_init_no_tc(), and buf type is
CIFS_SMALL_BUFFER, so we should use cifs_small_buf_release() to
release it in failed path.

Signed-off-by: Ding Hui <dinghui@sangfor.com.cn>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
gfs2: Don't call dlm after protocol is unmounted 2021-09-22T09:41:26+00:00 Bob Peterson rpeterso@redhat.com 2021-07-30T17:41:49+00:00 6aa628c45875e7b8cca81ed9447a12a0e8f3504a [ Upstream commit d1340f80f0b8066321b499a376780da00560e857 ] In the gfs2 withdraw sequence, the dlm protocol is unmounted with a call to lm_unmount. After a withdraw, users are allowed to unmount the withdrawn file system. But at that point we may still have glocks left over that we need to free via unmount's call to gfs2_gl_hash_clear. These glocks may have never been completed because of whatever problem caused the withdraw (IO errors or whatever). Before this patch, function gdlm_put_lock would still try to call into dlm to unlock these leftover glocks, which resulted in dlm returning -EINVAL because the lock space was abandoned. These glocks were never freed because there was no mechanism after that to free them. This patch adds a check to gdlm_put_lock to see if the locking protocol was inactive (DFL_UNMOUNT flag) and if so, free the glock and not make the invalid call into dlm. I could have combined this "if" with the one that follows, related to leftover glock LVBs, but I felt the code was more readable with its own if clause. Signed-off-by: Bob Peterson <rpeterso@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d1340f80f0b8066321b499a376780da00560e857 ]

In the gfs2 withdraw sequence, the dlm protocol is unmounted with a call
to lm_unmount. After a withdraw, users are allowed to unmount the
withdrawn file system. But at that point we may still have glocks left
over that we need to free via unmount's call to gfs2_gl_hash_clear.
These glocks may have never been completed because of whatever problem
caused the withdraw (IO errors or whatever).

Before this patch, function gdlm_put_lock would still try to call into
dlm to unlock these leftover glocks, which resulted in dlm returning
-EINVAL because the lock space was abandoned. These glocks were never
freed because there was no mechanism after that to free them.

This patch adds a check to gdlm_put_lock to see if the locking protocol
was inactive (DFL_UNMOUNT flag) and if so, free the glock and not
make the invalid call into dlm.

I could have combined this "if" with the one that follows, related to
leftover glock LVBs, but I felt the code was more readable with its own
if clause.

Signed-off-by: Bob Peterson <rpeterso@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
CIFS: Fix a potencially linear read overflow 2021-09-22T09:41:21+00:00 Len Baker len.baker@gmx.com 2021-08-17T10:27:09+00:00 0955df2d9bf4857e3e2287e3028903e6cec06c30 [ Upstream commit f980d055a0f858d73d9467bb0b570721bbfcdfb8 ] strlcpy() reads the entire source buffer first. This read may exceed the destination size limit. This is both inefficient and can lead to linear read overflows if a source string is not NUL-terminated. Also, the strnlen() call does not avoid the read overflow in the strlcpy function when a not NUL-terminated string is passed. So, replace this block by a call to kstrndup() that avoids this type of overflow and does the same. Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions") Signed-off-by: Len Baker <len.baker@gmx.com> Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz> Reviewed-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Steve French <stfrench@microsoft.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f980d055a0f858d73d9467bb0b570721bbfcdfb8 ]

strlcpy() reads the entire source buffer first. This read may exceed the
destination size limit. This is both inefficient and can lead to linear
read overflows if a source string is not NUL-terminated.

Also, the strnlen() call does not avoid the read overflow in the strlcpy
function when a not NUL-terminated string is passed.

So, replace this block by a call to kstrndup() that avoids this type of
overflow and does the same.

Fixes: 066ce6899484d ("cifs: rename cifs_strlcpy_to_host and make it use new functions")
Signed-off-by: Len Baker <len.baker@gmx.com>
Reviewed-by: Paulo Alcantara (SUSE) <pc@cjr.nz>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
udf_get_extendedattr() had no boundary checks. 2021-09-22T09:41:19+00:00 Stian Skjelstad stian.skjelstad@gmail.com 2021-08-22T09:33:32+00:00 983d381214ec8f9327597430c31dc0e00d8c1cd7 [ Upstream commit 58bc6d1be2f3b0ceecb6027dfa17513ec6aa2abb ] When parsing the ExtendedAttr data, malicous or corrupt attribute length could cause kernel hangs and buffer overruns in some special cases. Link: https://lore.kernel.org/r/20210822093332.25234-1-stian.skjelstad@gmail.com Signed-off-by: Stian Skjelstad <stian.skjelstad@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 58bc6d1be2f3b0ceecb6027dfa17513ec6aa2abb ]

When parsing the ExtendedAttr data, malicous or corrupt attribute length
could cause kernel hangs and buffer overruns in some special cases.

Link: https://lore.kernel.org/r/20210822093332.25234-1-stian.skjelstad@gmail.com
Signed-off-by: Stian Skjelstad <stian.skjelstad@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Revert "btrfs: compression: don't try to compress if we don't have enough pages" 2021-09-22T09:41:18+00:00 Qu Wenruo wqu@suse.com 2021-08-25T05:41:42+00:00 c5ae5b0af568f9015ec3a064a21ce5868664eaa7 commit 4e9655763b82a91e4c341835bb504a2b1590f984 upstream. This reverts commit f2165627319ffd33a6217275e5690b1ab5c45763. [BUG] It's no longer possible to create compressed inline extent after commit f2165627319f ("btrfs: compression: don't try to compress if we don't have enough pages"). [CAUSE] For compression code, there are several possible reasons we have a range that needs to be compressed while it's no more than one page. - Compressed inline write The data is always smaller than one sector and the test lacks the condition to properly recognize a non-inline extent. - Compressed subpage write For the incoming subpage compressed write support, we require page alignment of the delalloc range. And for 64K page size, we can compress just one page into smaller sectors. For those reasons, the requirement for the data to be more than one page is not correct, and is already causing regression for compressed inline data writeback. The idea of skipping one page to avoid wasting CPU time could be revisited in the future. [FIX] Fix it by reverting the offending commit. Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org> Link: https://lore.kernel.org/linux-btrfs/afa2742.c084f5d6.17b6b08dffc@tnonline.net Fixes: f2165627319f ("btrfs: compression: don't try to compress if we don't have enough pages") CC: stable@vger.kernel.org # 4.4+ Signed-off-by: Qu Wenruo <wqu@suse.com> Reviewed-by: David Sterba <dsterba@suse.com> Signed-off-by: David Sterba <dsterba@suse.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 4e9655763b82a91e4c341835bb504a2b1590f984 upstream.

This reverts commit f2165627319ffd33a6217275e5690b1ab5c45763.

[BUG]
It's no longer possible to create compressed inline extent after commit
f2165627319f ("btrfs: compression: don't try to compress if we don't
have enough pages").

[CAUSE]
For compression code, there are several possible reasons we have a range
that needs to be compressed while it's no more than one page.

- Compressed inline write
  The data is always smaller than one sector and the test lacks the
  condition to properly recognize a non-inline extent.

- Compressed subpage write
  For the incoming subpage compressed write support, we require page
  alignment of the delalloc range.
  And for 64K page size, we can compress just one page into smaller
  sectors.

For those reasons, the requirement for the data to be more than one page
is not correct, and is already causing regression for compressed inline
data writeback.  The idea of skipping one page to avoid wasting CPU time
could be revisited in the future.

[FIX]
Fix it by reverting the offending commit.

Reported-by: Zygo Blaxell <ce3g8jdj@umail.furryterror.org>
Link: https://lore.kernel.org/linux-btrfs/afa2742.c084f5d6.17b6b08dffc@tnonline.net
Fixes: f2165627319f ("btrfs: compression: don't try to compress if we don't have enough pages")
CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Qu Wenruo <wqu@suse.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ext4: fix race writing to an inline_data file while its xattrs are changing 2021-09-22T09:41:16+00:00 Theodore Ts'o tytso@mit.edu 2021-08-21T03:44:17+00:00 69d82df68fbc5e368820123200d7b88f6c058350 commit a54c4613dac1500b40e4ab55199f7c51f028e848 upstream. The location of the system.data extended attribute can change whenever xattr_sem is not taken. So we need to recalculate the i_inline_off field since it mgiht have changed between ext4_write_begin() and ext4_write_end(). This means that caching i_inline_off is probably not helpful, so in the long run we should probably get rid of it and shrink the in-memory ext4 inode slightly, but let's fix the race the simple way for now. Cc: stable@kernel.org Fixes: f19d5870cbf72 ("ext4: add normal write support for inline data") Reported-by: syzbot+13146364637c7363a7de@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit a54c4613dac1500b40e4ab55199f7c51f028e848 upstream.

The location of the system.data extended attribute can change whenever
xattr_sem is not taken.  So we need to recalculate the i_inline_off
field since it mgiht have changed between ext4_write_begin() and
ext4_write_end().

This means that caching i_inline_off is probably not helpful, so in
the long run we should probably get rid of it and shrink the in-memory
ext4 inode slightly, but let's fix the race the simple way for now.

Cc: stable@kernel.org
Fixes: f19d5870cbf72 ("ext4: add normal write support for inline data")
Reported-by: syzbot+13146364637c7363a7de@syzkaller.appspotmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ovl: prevent private clone if bind mount is not allowed 2021-08-15T10:59:57+00:00 Miklos Szeredi mszeredi@redhat.com 2021-08-09T08:19:47+00:00 c6e8810d25295acb40a7b69ed3962ff181919571 commit 427215d85e8d1476da1a86b8d67aceb485eb3631 upstream. Add the following checks from __do_loopback() to clone_private_mount() as well: - verify that the mount is in the current namespace - verify that there are no locked children Reported-by: Alois Wohlschlager <alois1@gmx-topmail.de> Fixes: c771d683a62e ("vfs: introduce clone_private_mount()") Cc: <stable@vger.kernel.org> # v3.18 Signed-off-by: Miklos Szeredi <mszeredi@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 427215d85e8d1476da1a86b8d67aceb485eb3631 upstream.

Add the following checks from __do_loopback() to clone_private_mount() as
well:

 - verify that the mount is in the current namespace

 - verify that there are no locked children

Reported-by: Alois Wohlschlager <alois1@gmx-topmail.de>
Fixes: c771d683a62e ("vfs: introduce clone_private_mount()")
Cc: <stable@vger.kernel.org> # v3.18
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pipe: increase minimum default pipe size to 2 pages 2021-08-15T10:59:56+00:00 Alex Xu (Hello71) alex_y_xu@yahoo.ca 2021-08-05T14:40:47+00:00 7392701d8615e923cc7ce55cd10e7155189a0062 commit 46c4c9d1beb7f5b4cec4dd90e7728720583ee348 upstream. This program always prints 4096 and hangs before the patch, and always prints 8192 and exits successfully after: int main() { int pipefd[2]; for (int i = 0; i < 1025; i++) if (pipe(pipefd) == -1) return 1; size_t bufsz = fcntl(pipefd[1], F_GETPIPE_SZ); printf("%zd\n", bufsz); char *buf = calloc(bufsz, 1); write(pipefd[1], buf, bufsz); read(pipefd[0], buf, bufsz-1); write(pipefd[1], buf, 1); } Note that you may need to increase your RLIMIT_NOFILE before running the program. Fixes: 759c01142a ("pipe: limit the per-user amount of pages allocated in pipes") Cc: <stable@vger.kernel.org> Link: https://lore.kernel.org/lkml/1628086770.5rn8p04n6j.none@localhost/ Link: https://lore.kernel.org/lkml/1628127094.lxxn016tj7.none@localhost/ Signed-off-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 46c4c9d1beb7f5b4cec4dd90e7728720583ee348 upstream.

This program always prints 4096 and hangs before the patch, and always
prints 8192 and exits successfully after:

  int main()
  {
      int pipefd[2];
      for (int i = 0; i < 1025; i++)
          if (pipe(pipefd) == -1)
              return 1;
      size_t bufsz = fcntl(pipefd[1], F_GETPIPE_SZ);
      printf("%zd\n", bufsz);
      char *buf = calloc(bufsz, 1);
      write(pipefd[1], buf, bufsz);
      read(pipefd[0], buf, bufsz-1);
      write(pipefd[1], buf, 1);
  }

Note that you may need to increase your RLIMIT_NOFILE before running the
program.

Fixes: 759c01142a ("pipe: limit the per-user amount of pages allocated in pipes")
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/lkml/1628086770.5rn8p04n6j.none@localhost/
Link: https://lore.kernel.org/lkml/1628127094.lxxn016tj7.none@localhost/
Signed-off-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
reiserfs: check directory items on read from disk 2021-08-15T10:59:56+00:00 Shreyansh Chouhan chouhan.shreyansh630@gmail.com 2021-07-09T15:29:29+00:00 4ababa17d7a14fd79eb92a5c135a999a6a51413f [ Upstream commit 13d257503c0930010ef9eed78b689cec417ab741 ] While verifying the leaf item that we read from the disk, reiserfs doesn't check the directory items, this could cause a crash when we read a directory item from the disk that has an invalid deh_location. This patch adds a check to the directory items read from the disk that does a bounds check on deh_location for the directory entries. Any directory entry header with a directory entry offset greater than the item length is considered invalid. Link: https://lore.kernel.org/r/20210709152929.766363-1-chouhan.shreyansh630@gmail.com Reported-by: syzbot+c31a48e6702ccb3d64c9@syzkaller.appspotmail.com Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 13d257503c0930010ef9eed78b689cec417ab741 ]

While verifying the leaf item that we read from the disk, reiserfs
doesn't check the directory items, this could cause a crash when we
read a directory item from the disk that has an invalid deh_location.

This patch adds a check to the directory items read from the disk that
does a bounds check on deh_location for the directory entries. Any
directory entry header with a directory entry offset greater than the
item length is considered invalid.

Link: https://lore.kernel.org/r/20210709152929.766363-1-chouhan.shreyansh630@gmail.com
Reported-by: syzbot+c31a48e6702ccb3d64c9@syzkaller.appspotmail.com
Signed-off-by: Shreyansh Chouhan <chouhan.shreyansh630@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
reiserfs: add check for root_inode in reiserfs_fill_super 2021-08-15T10:59:56+00:00 Yu Kuai yukuai3@huawei.com 2021-07-02T04:07:43+00:00 bbddd8fc929d04158aa9c1931736a05d27dee1ec [ Upstream commit 2acf15b94d5b8ea8392c4b6753a6ffac3135cd78 ] Our syzcaller report a NULL pointer dereference: BUG: kernel NULL pointer dereference, address: 0000000000000000 PGD 116e95067 P4D 116e95067 PUD 1080b5067 PMD 0 Oops: 0010 [#1] SMP KASAN CPU: 7 PID: 592 Comm: a.out Not tainted 5.13.0-next-20210629-dirty #67 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-p4 RIP: 0010:0x0 Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6. RSP: 0018:ffff888114e779b8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 1ffff110229cef39 RCX: ffffffffaa67e1aa RDX: 0000000000000000 RSI: ffff88810a58ee00 RDI: ffff8881233180b0 RBP: ffffffffac38e9c0 R08: ffffffffaa67e17e R09: 0000000000000001 R10: ffffffffb91c5557 R11: fffffbfff7238aaa R12: ffff88810a58ee00 R13: ffff888114e77aa0 R14: 0000000000000000 R15: ffff8881233180b0 FS: 00007f946163c480(0000) GS:ffff88839f1c0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffd6 CR3: 00000001099c1000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __lookup_slow+0x116/0x2d0 ? page_put_link+0x120/0x120 ? __d_lookup+0xfc/0x320 ? d_lookup+0x49/0x90 lookup_one_len+0x13c/0x170 ? __lookup_slow+0x2d0/0x2d0 ? reiserfs_schedule_old_flush+0x31/0x130 reiserfs_lookup_privroot+0x64/0x150 reiserfs_fill_super+0x158c/0x1b90 ? finish_unfinished+0xb10/0xb10 ? bprintf+0xe0/0xe0 ? __mutex_lock_slowpath+0x30/0x30 ? __kasan_check_write+0x20/0x30 ? up_write+0x51/0xb0 ? set_blocksize+0x9f/0x1f0 mount_bdev+0x27c/0x2d0 ? finish_unfinished+0xb10/0xb10 ? reiserfs_kill_sb+0x120/0x120 get_super_block+0x19/0x30 legacy_get_tree+0x76/0xf0 vfs_get_tree+0x49/0x160 ? capable+0x1d/0x30 path_mount+0xacc/0x1380 ? putname+0x97/0xd0 ? finish_automount+0x450/0x450 ? kmem_cache_free+0xf8/0x5a0 ? putname+0x97/0xd0 do_mount+0xe2/0x110 ? path_mount+0x1380/0x1380 ? copy_mount_options+0x69/0x140 __x64_sys_mount+0xf0/0x190 do_syscall_64+0x35/0x80 entry_SYSCALL_64_after_hwframe+0x44/0xae This is because 'root_inode' is initialized with wrong mode, and it's i_op is set to 'reiserfs_special_inode_operations'. Thus add check for 'root_inode' to fix the problem. Link: https://lore.kernel.org/r/20210702040743.1918552-1-yukuai3@huawei.com Signed-off-by: Yu Kuai <yukuai3@huawei.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 2acf15b94d5b8ea8392c4b6753a6ffac3135cd78 ]

Our syzcaller report a NULL pointer dereference:

BUG: kernel NULL pointer dereference, address: 0000000000000000
PGD 116e95067 P4D 116e95067 PUD 1080b5067 PMD 0
Oops: 0010 [#1] SMP KASAN
CPU: 7 PID: 592 Comm: a.out Not tainted 5.13.0-next-20210629-dirty #67
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ?-20190727_073836-buildvm-p4
RIP: 0010:0x0
Code: Unable to access opcode bytes at RIP 0xffffffffffffffd6.
RSP: 0018:ffff888114e779b8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 1ffff110229cef39 RCX: ffffffffaa67e1aa
RDX: 0000000000000000 RSI: ffff88810a58ee00 RDI: ffff8881233180b0
RBP: ffffffffac38e9c0 R08: ffffffffaa67e17e R09: 0000000000000001
R10: ffffffffb91c5557 R11: fffffbfff7238aaa R12: ffff88810a58ee00
R13: ffff888114e77aa0 R14: 0000000000000000 R15: ffff8881233180b0
FS:  00007f946163c480(0000) GS:ffff88839f1c0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffffffffd6 CR3: 00000001099c1000 CR4: 00000000000006e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 __lookup_slow+0x116/0x2d0
 ? page_put_link+0x120/0x120
 ? __d_lookup+0xfc/0x320
 ? d_lookup+0x49/0x90
 lookup_one_len+0x13c/0x170
 ? __lookup_slow+0x2d0/0x2d0
 ? reiserfs_schedule_old_flush+0x31/0x130
 reiserfs_lookup_privroot+0x64/0x150
 reiserfs_fill_super+0x158c/0x1b90
 ? finish_unfinished+0xb10/0xb10
 ? bprintf+0xe0/0xe0
 ? __mutex_lock_slowpath+0x30/0x30
 ? __kasan_check_write+0x20/0x30
 ? up_write+0x51/0xb0
 ? set_blocksize+0x9f/0x1f0
 mount_bdev+0x27c/0x2d0
 ? finish_unfinished+0xb10/0xb10
 ? reiserfs_kill_sb+0x120/0x120
 get_super_block+0x19/0x30
 legacy_get_tree+0x76/0xf0
 vfs_get_tree+0x49/0x160
 ? capable+0x1d/0x30
 path_mount+0xacc/0x1380
 ? putname+0x97/0xd0
 ? finish_automount+0x450/0x450
 ? kmem_cache_free+0xf8/0x5a0
 ? putname+0x97/0xd0
 do_mount+0xe2/0x110
 ? path_mount+0x1380/0x1380
 ? copy_mount_options+0x69/0x140
 __x64_sys_mount+0xf0/0x190
 do_syscall_64+0x35/0x80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

This is because 'root_inode' is initialized with wrong mode, and
it's i_op is set to 'reiserfs_special_inode_operations'. Thus add
check for 'root_inode' to fix the problem.

Link: https://lore.kernel.org/r/20210702040743.1918552-1-yukuai3@huawei.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>