[055/151] hfs: fix a potential buffer overflow

Greg KH
2009-12-17T04:36:49Z

From: Amerigo Wang <amwang@redhat.com>

commit ec81aecb29668ad71f699f4e7b96ec46691895b6 upstream.

A specially-crafted Hierarchical File System (HFS) filesystem could cause
a buffer overflow to occur in a process's kernel stack during a memcpy()
call within the hfs_bnode_read() function (at fs/hfs/bnode.c:24). The
attacker can provide the source buffer and length, and the destination
buffer is a local variable of a fixed length. This local variable (passed
as "&entry" from fs/hfs/dir.c:112 and allocated on line 60) is stored in
the stack frame of hfs_bnode_read()'s caller, which is hfs_readdir().
Because the hfs_readdir() function executes upon any attempt to read a
directory on the filesystem, it gets called whenever a user attempts to
inspect any filesystem contents.

[amwang@redhat.com: modify this patch and fix coding style problems]
Signed-off-by: WANG Cong <amwang@redhat.com>
Cc: Eugene Teo <eteo@redhat.com>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Dave Anderson <anderson@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
fs/hfs/catalog.c | 4 ++++
fs/hfs/dir.c | 11 +++++++++++
fs/hfs/super.c | 7 ++++++-
3 files changed, 21 insertions(+), 1 deletion(-)

--- a/fs/hfs/catalog.c
+++ b/fs/hfs/catalog.c
@@ -289,6 +289,10 @@ int hfs_cat_move(u32 cnid, struct inode
err = hfs_brec_find(&src_fd);
if (err)
goto out;
+ if (src_fd.entrylength > sizeof(entry) || src_fd.entrylength < 0) {
+ err = -EIO;
+ goto out;
+ }

hfs_bnode_read(src_fd.bnode, &entry, src_fd.entryoffset,
src_fd.entrylength);
--- a/fs/hfs/dir.c
+++ b/fs/hfs/dir.c
@@ -79,6 +79,11 @@ static int hfs_readdir(struct file *filp
filp->f_pos++;
/* fall through */
case 1:
+ if (fd.entrylength > sizeof(entry) || fd.entrylength < 0) {
+ err = -EIO;
+ goto out;
+ }
+
hfs_bnode_read(fd.bnode, &entry, fd.entryoffset, fd.entrylength);
if (entry.type != HFS_CDR_THD) {
printk(KERN_ERR "hfs: bad catalog folder thread\n");
@@ -109,6 +114,12 @@ static int hfs_readdir(struct file *filp
err = -EIO;
goto out;
}
+
+ if (fd.entrylength > sizeof(entry) || fd.entrylength < 0) {
+ err = -EIO;
+ goto out;
+ }
+
hfs_bnode_read(fd.bnode, &entry, fd.entryoffset, fd.entrylength);
type = entry.type;
len = hfs_mac2asc(sb, strbuf, &fd.key->cat.CName);
--- a/fs/hfs/super.c
+++ b/fs/hfs/super.c
@@ -409,8 +409,13 @@ static int hfs_fill_super(struct super_b
/* try to get the root inode */
hfs_find_init(HFS_SB(sb)->cat_tree, &fd);
res = hfs_cat_find_brec(sb, HFS_ROOT_CNID, &fd);
- if (!res)
+ if (!res) {
+ if (fd.entrylength > sizeof(rec) || fd.entrylength < 0) {
+ res = -EIO;
+ goto bail;
+ }
hfs_bnode_read(fd.bnode, &rec, fd.entryoffset, fd.entrylength);
+ }
if (res) {
hfs_find_exit(&fd);
goto bail_no_root;