+ fs-sysv-check-sbi-s_firstdatazone-in-complete_read_super.patch added to -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: fs: sysv: check sbi->s_firstdatazone in complete_read_super
has been added to the -mm tree.  Its filename is
     fs-sysv-check-sbi-s_firstdatazone-in-complete_read_super.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/fs-sysv-check-sbi-s_firstdatazone-in-complete_read_super.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/fs-sysv-check-sbi-s_firstdatazone-in-complete_read_super.patch

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------------------------------------------------------
From: Liu Shixin <liushixin2@huawei.com>
Subject: fs: sysv: check sbi->s_firstdatazone in complete_read_super

sbi->s_firstinodezone is initialized to 2 and sbi->s_firstdatazone is read
from sbd.  There's no guarantee that sbi->s_firstdatazone must bigger than
sbi->s_firstinodezone.  If sbi->s_firstdatazone less than 2, the
filesystem can still be mounted unexpetly.  At this point, sbi->s_ninodes
flip to very large value and this filesystem is broken.  We can observe
this by executing 'df' command.  When we execute, we will get an error
message:

	"sysv_count_free_inodes: unable to read inode table"

Link: https://lkml.kernel.org/r/20220330104215.530223-1-liushixin2@huawei.com
Signed-off-by: Liu Shixin <liushixin2@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 fs/sysv/super.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/fs/sysv/super.c~fs-sysv-check-sbi-s_firstdatazone-in-complete_read_super
+++ a/fs/sysv/super.c
@@ -312,7 +312,9 @@ static int complete_read_super(struct su
 	sbi->s_firstinodezone = 2;
 
 	flavour_setup[sbi->s_type](sbi, &sb->s_max_links);
-	
+	if (sbi->s_firstdatazone < sbi->s_firstinodezone)
+		return 0;
+
 	sbi->s_ndatazones = sbi->s_nzones - sbi->s_firstdatazone;
 	sbi->s_inodes_per_block = bsize >> 6;
 	sbi->s_inodes_per_block_1 = (bsize >> 6)-1;
_

Patches currently in -mm which might be from liushixin2@huawei.com are

fs-sysv-check-sbi-s_firstdatazone-in-complete_read_super.patch