pstore: Fix warning in pstore_kill_sb()

syzbot is hitting WARN_ON(pstore_sb != sb) at pstore_kill_sb() [1], for the
assumption that pstore_sb != NULL is wrong because pstore_fill_super() will
not assign pstore_sb = sb when new_inode() for d_make_root() returned NULL
(due to memory allocation fault injection).

Since mount_single() calls pstore_kill_sb() when pstore_fill_super()
failed, pstore_kill_sb() needs to be aware of such failure path.

[1] https://syzkaller.appspot.com/bug?id=6abacb8da5137cb47a416f2bef95719ed60508a0

Reported-by: syzbot <syzbot+d0cf0ad6513e9a1da5df@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210214031307.57903-1-penguin-kernel@I-love.SAKURA.ne.jp
This commit is contained in:
Tetsuo Handa 2021-02-14 12:13:07 +09:00 committed by Kees Cook
parent 19d8e9149c
commit 9c7d83ae6b

View File

@ -467,7 +467,7 @@ static struct dentry *pstore_mount(struct file_system_type *fs_type,
static void pstore_kill_sb(struct super_block *sb)
{
mutex_lock(&pstore_sb_lock);
WARN_ON(pstore_sb != sb);
WARN_ON(pstore_sb && pstore_sb != sb);
kill_litter_super(sb);
pstore_sb = NULL;