Commit 7464726c authored by Tetsuo Handa's avatar Tetsuo Handa Committed by Linus Torvalds

hfsplus: don't return 0 when fill_super() failed

syzbot is reporting NULL pointer dereference at mount_fs() [1].  This is
because hfsplus_fill_super() is by error returning 0 when
hfsplus_fill_super() detected invalid filesystem image, and mount_bdev()
is returning NULL because dget(s->s_root) == NULL if s->s_root == NULL,
and mount_fs() is accessing root->d_sb because IS_ERR(root) == false if
root == NULL.  Fix this by returning -EINVAL when hfsplus_fill_super()
detected invalid filesystem image.

[1] https://syzkaller.appspot.com/bug?id=21acb6850cecbc960c927229e597158cf35f33d0

Link: http://lkml.kernel.org/r/d83ce31a-874c-dd5b-f790-41405983a5be@I-love.SAKURA.ne.jpSigned-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: default avatarsyzbot <syzbot+01ffaf5d9568dd1609f7@syzkaller.appspotmail.com>
Reviewed-by: default avatarErnesto A. Fernández <ernesto.mnd.fernandez@gmail.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8ed98cd
...@@ -524,8 +524,10 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent) ...@@ -524,8 +524,10 @@ static int hfsplus_fill_super(struct super_block *sb, void *data, int silent)
goto out_put_root; goto out_put_root;
if (!hfs_brec_read(&fd, &entry, sizeof(entry))) { if (!hfs_brec_read(&fd, &entry, sizeof(entry))) {
hfs_find_exit(&fd); hfs_find_exit(&fd);
if (entry.type != cpu_to_be16(HFSPLUS_FOLDER)) if (entry.type != cpu_to_be16(HFSPLUS_FOLDER)) {
err = -EINVAL;
goto out_put_root; goto out_put_root;
}
inode = hfsplus_iget(sb, be32_to_cpu(entry.folder.id)); inode = hfsplus_iget(sb, be32_to_cpu(entry.folder.id));
if (IS_ERR(inode)) { if (IS_ERR(inode)) {
err = PTR_ERR(inode); err = PTR_ERR(inode);
......
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