[+Cc linux-crypto] On Wed, Jul 24, 2019 at 06:02:04PM +0800, Jia-Ju Bai wrote: > In derive_key_aes(), tfm is assigned to NULL on line 46, and then > crypto_free_skcipher(tfm) is executed. > > crypto_free_skcipher(tfm) > crypto_skcipher_tfm(tfm) > return &tfm->base; > > Thus, a possible null-pointer dereference may occur. This analysis is incorrect because only the address &tfm->base is taken. There's no pointer dereference. In fact all the crypto_free_*() functions are no-ops on NULL pointers, and many other callers rely on it. So there's no bug here. It appears you've sent the same patch for some of these other callers (https://lore.kernel.org/lkml/?q=%22fix+a+possible+null-pointer%22), but none are Cc'ed to linux-crypto or another mailing list I'm subscribed to, so I can't respond to them. But this feedback applies equally to them too. Note also that if there actually were a bug here (which again, there doesn't appear to be), we'd need to fix it in crypto_free_*(), not in the callers. - Eric
