| Message ID | 20201025143119.1054168-4-nivedita@alum.mit.edu |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [v4,1/6] crypto: lib/sha256 - Use memzero_explicit() for clearing state | expand |
On Sun, 25 Oct 2020 at 15:31, Arvind Sankar <nivedita@alum.mit.edu> wrote: > > The assignments to clear a through h and t1/t2 are optimized out by the > compiler because they are unused after the assignments. > > Clearing individual scalar variables is unlikely to be useful, as they > may have been assigned to registers, and even if stack spilling was > required, there may be compiler-generated temporaries that are > impossible to clear in any case. > > So drop the clearing of a through h and t1/t2. > > Signed-off-by: Arvind Sankar <nivedita@alum.mit.edu> > Reviewed-by: Eric Biggers <ebiggers@google.com> Acked-by: Ard Biesheuvel <ardb@kernel.org> > --- > lib/crypto/sha256.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c > index d43bc39ab05e..099cd11f83c1 100644 > --- a/lib/crypto/sha256.c > +++ b/lib/crypto/sha256.c > @@ -202,7 +202,6 @@ static void sha256_transform(u32 *state, const u8 *input) > state[4] += e; state[5] += f; state[6] += g; state[7] += h; > > /* clear any sensitive info... */ > - a = b = c = d = e = f = g = h = t1 = t2 = 0; > memzero_explicit(W, 64 * sizeof(u32)); > } > > -- > 2.26.2 >
diff --git a/lib/crypto/sha256.c b/lib/crypto/sha256.c index d43bc39ab05e..099cd11f83c1 100644 --- a/lib/crypto/sha256.c +++ b/lib/crypto/sha256.c @@ -202,7 +202,6 @@ static void sha256_transform(u32 *state, const u8 *input) state[4] += e; state[5] += f; state[6] += g; state[7] += h; /* clear any sensitive info... */ - a = b = c = d = e = f = g = h = t1 = t2 = 0; memzero_explicit(W, 64 * sizeof(u32)); }