From b32a09db4fb9a87246ba4e7726a979ac4709ad97 Mon Sep 17 00:00:00 2001 From: Markus Armbruster Date: Tue, 26 Feb 2008 09:57:11 -0600 Subject: add match_strlcpy() us it to make v9fs make uname and remotename parsing more robust match_strcpy() is a somewhat creepy function: the caller needs to make sure that the destination buffer is big enough, and when he screws up or forgets, match_strcpy() happily overruns the buffer. There's exactly one customer: v9fs_parse_options(). I believe it currently can't overflow its buffer, but that's not exactly obvious. The source string is a substing of the mount options. The kernel silently truncates those to PAGE_SIZE bytes, including the terminating zero. See compat_sys_mount() and do_mount(). The destination buffer is obtained from __getname(), which allocates from name_cachep, which is initialized by vfs_caches_init() for size PATH_MAX. We're safe as long as PATH_MAX <= PAGE_SIZE. PATH_MAX is 4096. As far as I know, the smallest PAGE_SIZE is also 4096. Here's a patch that makes the code a bit more obviously correct. It doesn't depend on PATH_MAX <= PAGE_SIZE. Signed-off-by: Markus Armbruster Cc: Latchesar Ionkov Cc: Jim Meyering Cc: "Randy.Dunlap" Signed-off-by: Andrew Morton Signed-off-by: Eric Van Hensbergen --- fs/9p/v9fs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'fs/9p') diff --git a/fs/9p/v9fs.c b/fs/9p/v9fs.c index 9b0f0222e8b..e307fbd34fa 100644 --- a/fs/9p/v9fs.c +++ b/fs/9p/v9fs.c @@ -125,10 +125,10 @@ static void v9fs_parse_options(struct v9fs_session_info *v9ses) v9ses->afid = option; break; case Opt_uname: - match_strcpy(v9ses->uname, &args[0]); + match_strlcpy(v9ses->uname, &args[0], PATH_MAX); break; case Opt_remotename: - match_strcpy(v9ses->aname, &args[0]); + match_strlcpy(v9ses->aname, &args[0], PATH_MAX); break; case Opt_nodevmap: v9ses->nodev = 1; -- cgit v1.2.3