From: Amerigo Wang <amwang@redhat.com> Date: Fri, 4 Dec 2009 09:26:22 -0500 Subject: [fs] hfs: fix a potential buffer overflow Message-id: <20091204092922.4639.92542.sendpatchset@localhost.localdomain> Patchwork-id: 21677 O-Subject: [PATCH RHEL5.x][CVE-2009-4020] hfs: fix a potential buffer overflow Bugzilla: 540741 CVE: CVE-2009-4020 RH-Acked-by: Eric Sandeen <sandeen@redhat.com> CVE-2009-4020 (This bug is public now.) BZ: https://bugzilla.redhat.com/show_bug.cgi?id=540741 Description: 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. Brew: https://brewweb.devel.redhat.com/taskinfo?taskID=2125860 Upstream status: http://marc.info/?l=linux-mm-commits&m=125987755823047&w=2 Test status: With the test image from Eugene, I can confirm it fixes the problem. Signed-off-by: WANG Cong <amwang@redhat.com> diff --git a/fs/hfs/catalog.c b/fs/hfs/catalog.c index 6d98f11..424b033 100644 --- a/fs/hfs/catalog.c +++ b/fs/hfs/catalog.c @@ -289,6 +289,10 @@ int hfs_cat_move(u32 cnid, struct inode *src_dir, struct qstr *src_name, 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); diff --git a/fs/hfs/dir.c b/fs/hfs/dir.c index 7cd8cc0..9a10af6 100644 --- a/fs/hfs/dir.c +++ b/fs/hfs/dir.c @@ -79,6 +79,11 @@ static int hfs_readdir(struct file *filp, void *dirent, filldir_t filldir) 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, void *dirent, filldir_t filldir) 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); diff --git a/fs/hfs/super.c b/fs/hfs/super.c index 9882a90..b633b66 100644 --- a/fs/hfs/super.c +++ b/fs/hfs/super.c @@ -385,8 +385,13 @@ static int hfs_fill_super(struct super_block *sb, void *data, int silent) /* 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;