linux-ext4 - [PATCH v2 32/31] libext2fs: initialize i_extra

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Date:	Mon, 22 Dec 2014 14:55:29 -0800
From:	"Darrick J. Wong" <darrick.wong@...cle.com>
To:	tytso@....edu
Cc:	linux-ext4@...r.kernel.org, Andreas Dilger <adilger@...ger.ca>
Subject: [PATCH v2 32/31] libext2fs: initialize i_extra_isize when writing EAs

If i_extra_isize is zero when we try to write extended attributes,
we'll end up writing the EA magic into the i_extra_isize field, which
causes a subsequent crash on big endian systems (when we try to write
0xEA02 bytes past the inode!).  Therefore when the field is zero, set
i_extra_isize to the desired extra_isize size, zero those bytes, and
write the EAs after the end of the extended inode.

v2: Don't bother if we have 128b inodes; ensure that the value
is 32b-aligned so that the EA magic starts on a 32b boundary if
the superblock doesn't tell us otherwise.

Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>
---
 lib/ext2fs/ext_attr.c                    |   12 ++++++++++++
 tests/f_write_ea_no_extra_isize/expect.1 |   12 ++++++++++++
 tests/f_write_ea_no_extra_isize/expect.2 |    7 +++++++
 tests/f_write_ea_no_extra_isize/image.gz |  Bin
 tests/f_write_ea_no_extra_isize/name     |    1 +
 5 files changed, 32 insertions(+)
 create mode 100644 tests/f_write_ea_no_extra_isize/expect.1
 create mode 100644 tests/f_write_ea_no_extra_isize/expect.2
 create mode 100644 tests/f_write_ea_no_extra_isize/image.gz
 create mode 100644 tests/f_write_ea_no_extra_isize/name

diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index 70bc3f9..c6fcf54 100644
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -519,6 +519,18 @@ errcode_t ext2fs_xattrs_write(struct ext2_xattr_handle *handle)
 	if (err)
 		goto out;
 
+	/* If extra_isize isn't set, we need to set it now */
+	if (inode->i_extra_isize == 0 &&
+	    EXT2_INODE_SIZE(handle->fs->super) > EXT2_GOOD_OLD_INODE_SIZE) {
+		char *p = (char *)inode;
+		size_t extra = handle->fs->super->s_want_extra_isize;
+
+		if (extra == 0)
+			extra = sizeof(__u32);
+		memset(p + EXT2_GOOD_OLD_INODE_SIZE, 0, extra);
+		inode->i_extra_isize = extra;
+	}
+
 	move_inline_data_to_front(handle);
 
 	x = handle->attrs;
diff --git a/tests/f_write_ea_no_extra_isize/expect.1 b/tests/f_write_ea_no_extra_isize/expect.1
new file mode 100644
index 0000000..b7e7438
--- /dev/null
+++ b/tests/f_write_ea_no_extra_isize/expect.1
@@ -0,0 +1,12 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Directory inode 12, block #0, offset 4: directory corrupted
+Salvage? yes
+
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+
+test_filesys: ***** FILE SYSTEM WAS MODIFIED *****
+test_filesys: 12/128 files (0.0% non-contiguous), 17/512 blocks
+Exit status is 1
diff --git a/tests/f_write_ea_no_extra_isize/expect.2 b/tests/f_write_ea_no_extra_isize/expect.2
new file mode 100644
index 0000000..3b6073e
--- /dev/null
+++ b/tests/f_write_ea_no_extra_isize/expect.2
@@ -0,0 +1,7 @@
+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+test_filesys: 12/128 files (0.0% non-contiguous), 17/512 blocks
+Exit status is 0
diff --git a/tests/f_write_ea_no_extra_isize/image.gz b/tests/f_write_ea_no_extra_isize/image.gz
new file mode 100644
index 0000000000000000000000000000000000000000..928daff1f344824d357e816883a98b2cdfdaffb3
GIT binary patch
literal 2516
zcmb2|=3qFkI6Z`k`Ry&+Y!OEZh6m-}^`s^_@...jpj4;eVQ?ceQSj)oL#Gnz1=cLm
zv~lFfFtI=2=98SCs6XwXQ}-6Ju%@X>9fI9126HxlZ#2Be**0UwlghsG_L*~cr<Q$x
zcJJ<Oj)e8Ibj2!<JPfHhr<Aq!+aA$gzRhQoDpTqfm88@...xlMdNpU)@t~~i`mk$S
zzoVyaURhCSpQJX`e|`A<yOq_6FK*5jUa#jL8+)&B<F~W5)<2(II(+ff@...~@@wXt
zO0r@...aDG$2W8iznog0p}+h^;VVXl4ZK}{zBqI(?)|f0Y^ht>t&nbG@...$3=B7Z
zzWX-qadqb7_v@...2ZzY{r}&1;?u?qJ8lDkN;|V_HErb@...&eIeY8H?91Epe8gTW
z#qp>8%-!w_RG#4e@...Y_#Xxt|AD*%>jF1&gXpjJK#~;jC;IEb(o&#~gzJUuETrf}
zRok%tV=6ElWvesq%s;o>RW(Vqw|cASS<|O4a;NN_xHR?tb)Bt$LbgmbOZ<IUQ%o$p
zUwq@...YK3-Tr^z+swV;J`Rs%pZ#BB`ad`3|E{WQssEz?TR&NG;97*nr}>xXe%f!t
zxAoKf7Zd(Zk&?Xh?1}x|{r`U+Uwh*Jxur#4xBt=4FJGCGo%NMBXYuokNl*KaC%k*G
zu}tK){;6+2PXDfdYaO{ZbnaGE_m1*LLtr!nMnhmU1V%$(Gz6#@0(bv1g#8Yk!N8!v
F003fX5hwrv

literal 0
HcmV?d00001

diff --git a/tests/f_write_ea_no_extra_isize/name b/tests/f_write_ea_no_extra_isize/name
new file mode 100644
index 0000000..200e365
--- /dev/null
+++ b/tests/f_write_ea_no_extra_isize/name
@@ -0,0 +1 @@
+write EA when i_extra_size is zero
--
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