Re: udf: Suspicious values in udf_statfs()

[Jan Kara <jack@suse.cz>]

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On Mon 13-01-20 13:08:51, Jan Kara wrote:
> Hello,
> 
> On Sun 12-01-20 17:23:11, Pali Rohár wrote:
> > I looked at udf_statfs() implementation and I see there two things which
> > are probably incorrect:
> > 
> > First one:
> > 
> > 	buf->f_blocks = sbi->s_partmaps[sbi->s_partition].s_partition_len;
> > 
> > If sbi->s_partition points to Metadata partition then reported number
> > of blocks seems to be incorrect. Similar like in udf_count_free().
> 
> Oh, right. This needs similar treatment like udf_count_free(). I'll fix it.
> Thanks for spotting.

Patch for this is attached.

								Honza

-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

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From 2e831a1fb4fa4a6843e154edb1d9e80a1c610803 Mon Sep 17 00:00:00 2001
From: Jan Kara <jack@suse.cz>
Date: Fri, 17 Jan 2020 12:41:39 +0100
Subject: [PATCH] udf: Handle metadata partition better for statfs(2)
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
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When the filesystem uses Metadata partition, we need to look at the
underlying partition to get real total number of blocks in the
filesystem. Do the necessary remapping in udf_statfs().

Reported-by: Pali Rohár <pali.rohar@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
---
 fs/udf/super.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/fs/udf/super.c b/fs/udf/super.c
index f747bf72edbe..3bb9793db3aa 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -2395,11 +2395,17 @@ static int udf_statfs(struct dentry *dentry, struct kstatfs *buf)
 	struct udf_sb_info *sbi = UDF_SB(sb);
 	struct logicalVolIntegrityDescImpUse *lvidiu;
 	u64 id = huge_encode_dev(sb->s_bdev->bd_dev);
+	unsigned int part = sbi->s_partition;
+	int ptype = sbi->s_partmaps[part].s_partition_type;
 
+	if (ptype == UDF_METADATA_MAP25) {
+		part = sbi->s_partmaps[part].s_type_specific.s_metadata.
+							s_phys_partition_ref;
+	}
 	lvidiu = udf_sb_lvidiu(sb);
 	buf->f_type = UDF_SUPER_MAGIC;
 	buf->f_bsize = sb->s_blocksize;
-	buf->f_blocks = sbi->s_partmaps[sbi->s_partition].s_partition_len;
+	buf->f_blocks = sbi->s_partmaps[part].s_partition_len;
 	buf->f_bfree = udf_count_free(sb);
 	buf->f_bavail = buf->f_bfree;
 	/*
-- 
2.16.4