From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> commit 9c7d83ae6ba67d6c6199cce24573983db3b56332 upstream. 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@xxxxxxxxxxxxxxxxxxxxxxxxx> Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx> Link: https://lore.kernel.org/r/20210214031307.57903-1-penguin-kernel@xxxxxxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- fs/pstore/inode.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/fs/pstore/inode.c +++ b/fs/pstore/inode.c @@ -467,7 +467,7 @@ static struct dentry *pstore_mount(struc 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;
