Re: [PATCH] evm: check return values of crypto_shash functions

On Tue, Aug 11, 2026 at 09:40:36AM +0800, Roberto Sassu wrote:
> On 8/7/2026 7:42 PM, Roberto Sassu wrote:
> > On Tue, 2026-08-04 at 16:07 -0400, Mimi Zohar wrote:
> > > From: Daniel Hodges <[email protected]>
> > > 
> > > The crypto_shash_update() and crypto_shash_final() functions can fail
> > > and return error codes, but their return values were not being checked
> > > in several places in security/integrity/evm/evm_crypto.c:
> > > 
> > > - hmac_add_misc() ignored returns from crypto_shash_update() and
> > >    crypto_shash_final()
> > > - evm_calc_hmac_or_hash() ignored returns from crypto_shash_update()
> > > - evm_init_hmac() ignored returns from crypto_shash_update()
> > > 
> > > If these hash operations fail silently, the resulting HMAC could be
> > > invalid or incomplete, which could weaken the integrity verification
> > > security that EVM provides.
> > > 
> > > This patch converts hmac_add_misc() from void to int return type and
> > > adds proper error checking and propagation for all crypto_shash_*
> > > function calls. All callers are updated to handle the new return values.
> > > Additionally, error messages are logged when cryptographic operations
> > > fail to provide visibility into the failure rather than silently
> > > returning error codes.
> > > 
> > > Fixes: 66dbc325afce ("evm: re-release")
> > > Signed-off-by: Daniel Hodges <[email protected]>
> > > Reviewed-by: Roberto Sassu <[email protected]>
> > 
> > Looks good to me. I confirm the Reviewed-by.
> 
> We got a report from Sashiko. As it pointed out, we should not override the
> error when calling hmac_add_misc() if no xattr is present
> (-ENODATA).
> 
> Roberto

Looks good to me, thanks for fix!

Reviewed-by: Daniel Hodges <[email protected]>