udf: Protect default inode credentials by rwlock

Superblock carries credentials (uid, gid, etc.) which are used as default
values in __udf_read_inode() when media does not provide these. These
credentials can change during remount so we protect them by a rwlock so that
each inode gets a consistent set of credentials.

Signed-off-by: Jan Kara <jack@suse.cz>

1 files changed, 3 insertions, 0 deletions

diff --git a/fs/udf/super.c b/fs/udf/super.c
index e54960c0e960..f06cc67cf864 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -568,12 +568,14 @@ static int udf_remount_fs(struct super_block *sb, int *flags, char *options)
                 return -EINVAL;
 
         lock_kernel();
+        write_lock(&sbi->s_cred_lock);
         sbi->s_flags = uopt.flags;
         sbi->s_uid   = uopt.uid;
         sbi->s_gid   = uopt.gid;
         sbi->s_umask = uopt.umask;
         sbi->s_fmode = uopt.fmode;
         sbi->s_dmode = uopt.dmode;
+        write_unlock(&sbi->s_cred_lock);
 
         if (sbi->s_lvid_bh) {
                 int write_rev = le16_to_cpu(udf_sb_lvidiu(sbi)->minUDFWriteRev);
@@ -1960,6 +1962,7 @@ static int udf_fill_super(struct super_block *sb, void *options, int silent)
         sbi->s_fmode = uopt.fmode;
         sbi->s_dmode = uopt.dmode;
         sbi->s_nls_map = uopt.nls_map;
+        rwlock_init(&sbi->s_cred_lock);
 
         if (uopt.session == 0xFFFFFFFF)
                 sbi->s_session = udf_get_last_session(sb);