From ec81aecb29668ad71f699f4e7b96ec46691895b6 Mon Sep 17 00:00:00 2001 From: Amerigo Wang Date: Mon, 14 Dec 2009 17:57:37 -0800 Subject: hfs: fix a potential buffer overflow 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 Cc: Eugene Teo Cc: Roman Zippel Cc: Al Viro Cc: Christoph Hellwig Cc: Alexey Dobriyan Cc: Dave Anderson Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- fs/hfs/super.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'fs/hfs/super.c') diff --git a/fs/hfs/super.c b/fs/hfs/super.c index f7fcbe49da7..5ed7252b7b2 100644 --- a/fs/hfs/super.c +++ b/fs/hfs/super.c @@ -409,8 +409,13 @@ 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; -- cgit v1.2.3