From: Darrick J. Wong <darrick.wong@oracle.com>
Date: Sun, 10 Aug 2014 22:21:16 +0000 (-0400)
Subject: libext2fs: check EA value offset
X-Git-Tag: v1.43-WIP-2015-05-18~243
X-Git-Url: https://git.whamcloud.com/?a=commitdiff_plain;h=71e177a2a52a6253f03ca5218017e6b7a4a01ec6;p=tools%2Fe2fsprogs.git

libext2fs: check EA value offset

Perform a little more sanity checking of EA value offsets so that we
don't crash while trying to load things from the filesystem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
---

diff --git a/lib/ext2fs/ext2_err.et.in b/lib/ext2fs/ext2_err.et.in
index 2194a18..6b6d8b8 100644
--- a/lib/ext2fs/ext2_err.et.in
+++ b/lib/ext2fs/ext2_err.et.in
@@ -518,4 +518,7 @@ ec	EXT2_ET_MAGIC_EA_HANDLE,
 ec	EXT2_ET_INODE_IS_GARBAGE,
 	"Inode seems to contain garbage"
 
+ec	EXT2_ET_EA_BAD_VALUE_OFFSET,
+	"Extended attribute has an invalid value offset"
+
 	end
diff --git a/lib/ext2fs/ext_attr.c b/lib/ext2fs/ext_attr.c
index f3fba96..96530f8 100644
--- a/lib/ext2fs/ext_attr.c
+++ b/lib/ext2fs/ext_attr.c
@@ -624,6 +624,8 @@ static errcode_t read_xattrs_from_buffer(struct ext2_xattr_handle *handle,
 	void *ptr;
 	unsigned int remain, prefix_len;
 	errcode_t err;
+	unsigned int values_size = storage_size +
+			((char *)entries - (char *)value_start);
 
 	x = handle->attrs;
 	while (x->name)
@@ -648,6 +650,9 @@ static errcode_t read_xattrs_from_buffer(struct ext2_xattr_handle *handle,
 		if (entry->e_value_size > remain)
 			return EXT2_ET_EA_BAD_VALUE_SIZE;
 
+		if (entry->e_value_offs + entry->e_value_size > values_size)
+			return EXT2_ET_EA_BAD_VALUE_OFFSET;
+
 		/* e_value_block must be 0 in inode's ea */
 		if (entry->e_value_block != 0)
 			return EXT2_ET_BAD_EA_BLOCK_NUM;