Fix remount races with symlink handling in affs
A couple of fields in affs_sb_info is used in follow_link() and
symlink() for handling AFFS "absolute" symlinks. Need locking
against affs_remount() updates.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/affs/super.c b/fs/affs/super.c
index b2a5958..be6a6e8 100644
--- a/fs/affs/super.c
+++ b/fs/affs/super.c
@@ -221,8 +221,6 @@
*mount_opts |= SF_MUFS;
break;
case Opt_prefix:
- /* Free any previous prefix */
- kfree(*prefix);
*prefix = match_strdup(&args[0]);
if (!*prefix)
return 0;
@@ -311,6 +309,7 @@
return -ENOMEM;
sb->s_fs_info = sbi;
mutex_init(&sbi->s_bmlock);
+ spin_lock_init(&sbi->symlink_lock);
if (!parse_options(data,&uid,&gid,&i,&reserved,&root_block,
&blocksize,&sbi->s_prefix,
@@ -518,14 +517,18 @@
unsigned long mount_flags;
int res = 0;
char *new_opts = kstrdup(data, GFP_KERNEL);
+ char volume[32];
+ char *prefix = NULL;
pr_debug("AFFS: remount(flags=0x%x,opts=\"%s\")\n",*flags,data);
*flags |= MS_NODIRATIME;
+ memcpy(volume, sbi->s_volume, 32);
if (!parse_options(data, &uid, &gid, &mode, &reserved, &root_block,
- &blocksize, &sbi->s_prefix, sbi->s_volume,
+ &blocksize, &prefix, volume,
&mount_flags)) {
+ kfree(prefix);
kfree(new_opts);
return -EINVAL;
}
@@ -536,6 +539,14 @@
sbi->s_mode = mode;
sbi->s_uid = uid;
sbi->s_gid = gid;
+ /* protect against readers */
+ spin_lock(&sbi->symlink_lock);
+ if (prefix) {
+ kfree(sbi->s_prefix);
+ sbi->s_prefix = prefix;
+ }
+ memcpy(sbi->s_volume, volume, 32);
+ spin_unlock(&sbi->symlink_lock);
if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) {
unlock_kernel();