On Mon, Jun 23, 2025 at 11:40:39AM +0200, Mikulas Patocka wrote: > > > On Fri, 20 Jun 2025, Milan Broz wrote: > > > Hi, > > > > On 6/20/25 6:09 AM, Herbert Xu wrote: > > > The output buffer size of of crypto_shash_export is returned by > > > crypto_shash_statesize. Alternatively HASH_MAX_STATESIZE may be > > > used for stack buffers. > > > > > > Fixes: 8cf4c341f193 ("crypto: md5-generic - Use API partial block > > > handling") > > > Reported-by: Milan Broz <gmazyl...@gmail.com> > > > Signed-off-by: Herbert Xu <herb...@gondor.apana.org.au> > > > > Yes, that fixes the issue, thanks! > > > > Tested-by: Milan Broz <gmazyl...@gmail.com> > > > > Mikulas, I think this should go through DM tree, could you send it for 6.16? > > The full patch is here > > https://lore.kernel.org/linux-crypto/afte3kdzxcazc...@gondor.apana.org.au/T/#u > > > > > diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c > > > index 9dfdb63220d7..cb4617df7356 100644 > > > --- a/drivers/md/dm-crypt.c > > > +++ b/drivers/md/dm-crypt.c > > > @@ -517,7 +517,10 @@ static int crypt_iv_lmk_one(struct crypt_config *cc, > > > u8 > > > *iv, > > > { > > > struct iv_lmk_private *lmk = &cc->iv_gen_private.lmk; > > > SHASH_DESC_ON_STACK(desc, lmk->hash_tfm); > > > - struct md5_state md5state; > > > + union { > > > + struct md5_state md5state; > > > + u8 state[HASH_MAX_STATESIZE]; > > > + } u; > > Hi > > 345 bytes on the stack - I think it's too much, given the fact that it > already uses 345 bytes (from SHASH_DESC_ON_STACK) and it may be called in > a tasklet context. I'd prefer a solution that allocates less bytes.
Of course, the correct solution is to just add MD5 support to lib/crypto/ and use that here. All that's needed is a single MD5 context (88 bytes), and direct calls to the MD5 code... - Eric