This is a note to let you know that I've just added the patch titled
ext4: check EA value offset when loading
to the 3.17-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ext4-check-ea-value-offset-when-loading.patch
and it can be found in the queue-3.17 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From a0626e75954078cfacddb00a4545dde821170bc5 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
Date: Tue, 16 Sep 2014 14:34:59 -0400
Subject: ext4: check EA value offset when loading
From: "Darrick J. Wong" <darrick.wong@xxxxxxxxxx>
commit a0626e75954078cfacddb00a4545dde821170bc5 upstream.
When loading extended attributes, check each entry's value offset to
make sure it doesn't collide with the entries.
Without this check it is easy to crash the kernel by mounting a
malicious FS containing a file with an EA wherein e_value_offs = 0 and
e_value_size > 0 and then deleting the EA, which corrupts the name
list.
(See the f_ea_value_crash test's FS image in e2fsprogs for an example.)
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/ext4/xattr.c | 32 ++++++++++++++++++++++++--------
1 file changed, 24 insertions(+), 8 deletions(-)
--- a/fs/ext4/xattr.c
+++ b/fs/ext4/xattr.c
@@ -190,14 +190,28 @@ ext4_listxattr(struct dentry *dentry, ch
}
static int
-ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end)
+ext4_xattr_check_names(struct ext4_xattr_entry *entry, void *end,
+ void *value_start)
{
- while (!IS_LAST_ENTRY(entry)) {
- struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(entry);
+ struct ext4_xattr_entry *e = entry;
+
+ while (!IS_LAST_ENTRY(e)) {
+ struct ext4_xattr_entry *next = EXT4_XATTR_NEXT(e);
if ((void *)next >= end)
return -EIO;
- entry = next;
+ e = next;
}
+
+ while (!IS_LAST_ENTRY(entry)) {
+ if (entry->e_value_size != 0 &&
+ (value_start + le16_to_cpu(entry->e_value_offs) <
+ (void *)e + sizeof(__u32) ||
+ value_start + le16_to_cpu(entry->e_value_offs) +
+ le32_to_cpu(entry->e_value_size) > end))
+ return -EIO;
+ entry = EXT4_XATTR_NEXT(entry);
+ }
+
return 0;
}
@@ -214,7 +228,8 @@ ext4_xattr_check_block(struct inode *ino
return -EIO;
if (!ext4_xattr_block_csum_verify(inode, bh->b_blocknr, BHDR(bh)))
return -EIO;
- error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size);
+ error = ext4_xattr_check_names(BFIRST(bh), bh->b_data + bh->b_size,
+ bh->b_data);
if (!error)
set_buffer_verified(bh);
return error;
@@ -331,7 +346,7 @@ ext4_xattr_ibody_get(struct inode *inode
header = IHDR(inode, raw_inode);
entry = IFIRST(header);
end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
- error = ext4_xattr_check_names(entry, end);
+ error = ext4_xattr_check_names(entry, end, entry);
if (error)
goto cleanup;
error = ext4_xattr_find_entry(&entry, name_index, name,
@@ -463,7 +478,7 @@ ext4_xattr_ibody_list(struct dentry *den
raw_inode = ext4_raw_inode(&iloc);
header = IHDR(inode, raw_inode);
end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
- error = ext4_xattr_check_names(IFIRST(header), end);
+ error = ext4_xattr_check_names(IFIRST(header), end, IFIRST(header));
if (error)
goto cleanup;
error = ext4_xattr_list_entries(dentry, IFIRST(header),
@@ -986,7 +1001,8 @@ int ext4_xattr_ibody_find(struct inode *
is->s.here = is->s.first;
is->s.end = (void *)raw_inode + EXT4_SB(inode->i_sb)->s_inode_size;
if (ext4_test_inode_state(inode, EXT4_STATE_XATTR)) {
- error = ext4_xattr_check_names(IFIRST(header), is->s.end);
+ error = ext4_xattr_check_names(IFIRST(header), is->s.end,
+ IFIRST(header));
if (error)
return error;
/* Find the named attribute. */
Patches currently in stable-queue which might be from darrick.wong@xxxxxxxxxx are
queue-3.17/ext4-check-s_chksum_driver-when-looking-for-bg-csum-presence.patch
queue-3.17/ext4-check-ea-value-offset-when-loading.patch
queue-3.17/x86-bpf_jit-fix-two-bugs-in-ebpf-jit-compiler.patch
queue-3.17/jbd2-free-bh-when-descriptor-block-checksum-fails.patch
queue-3.17/ext4-enable-journal-checksum-when-metadata-checksum-feature-enabled.patch
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