Re: [PATCH 1/3] dm integrity: do not filter algos with CRYPTO_ALG_ALLOCATES_MEMORY

[Eric Biggers]

On Wed, Jul 05, 2023 at 05:40:07PM +0100, Giovanni Cabiddu wrote:
> The flag CRYPTO_ALG_ALLOCATES_MEMORY indicates that an algorithm might
> allocate memory in the datapath and therefore sleep.
> Dm-integrity is filtering out implementations of skcipher algorithms
> that have this flag set. However, in the same function it does
> allocations with GFP_KERNEL.

Which function is the above referring to?  The actual encryption/decryption
happens in crypt_journal(), and I don't see any memory allocations there.

> As dm-integrity is re-entrant and capable of handling sleeps that could
> occur during allocations with GFP_KERNEL, then it is also capable of
> using skcipher algorithm implementations that have
> CRYPTO_ALG_ALLOCATES_MEMORY set.
> 
> Remove the filtering of skcipher implementations with the flag
> CRYPTO_ALG_ALLOCATES_MEMORY set.

What about the use of CRYPTO_ALG_ALLOCATES_MEMORY in get_mac()?

> 
> Suggested-by: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
> Link: https://lore.kernel.org/linux-crypto/ZILvtASXQKLG43y9@xxxxxxxxxxxxxxxxxxx/
> Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@xxxxxxxxx>
> Reviewed-by: Fiona Trahe <fiona.trahe@xxxxxxxxx>

This needs:

    Fixes: a7a10bce8a04 ("dm integrity: don't use drivers that have CRYPTO_ALG_ALLOCATES_MEMORY")
    Cc: stable@xxxxxxxxxxxxxxx

But, are you 100% sure the explanation in commit a7a10bce8a04 was incorrect?

- Eric