[PATCH 1/2] crypto: x86/aegis - Fix sleeping when disallowed on PREEMPT_RT

[Eric Biggers <ebiggers@kernel.org>]

skcipher_walk_done() can call kfree(), which takes a spinlock, which
makes it incorrect to call while preemption is disabled on PREEMPT_RT.
Therefore, end the kernel-mode FPU section before calling
skcipher_walk_done(), and restart it afterwards.

Moreover, pass atomic=false to skcipher_walk_aead_encrypt() instead of
atomic=true.  The point of atomic=true was to make skcipher_walk_done()
safe to call while in a kernel-mode FPU section, but that does not
actually work.  So just use the usual atomic=false.

Fixes: 1d373d4e8e15 ("crypto: x86 - Add optimized AEGIS implementations")
Cc: stable@vger.kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
---
 arch/x86/crypto/aegis128-aesni-glue.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/crypto/aegis128-aesni-glue.c b/arch/x86/crypto/aegis128-aesni-glue.c
index f1b6d40154e35..3cb5c193038bb 100644
--- a/arch/x86/crypto/aegis128-aesni-glue.c
+++ b/arch/x86/crypto/aegis128-aesni-glue.c
@@ -117,11 +117,13 @@ crypto_aegis128_aesni_process_crypt(struct aegis_state *state,
 		else
 			aegis128_aesni_dec(state, walk->src.virt.addr,
 					   walk->dst.virt.addr,
 					   round_down(walk->nbytes,
 						      AEGIS128_BLOCK_SIZE));
+		kernel_fpu_end();
 		skcipher_walk_done(walk, walk->nbytes % AEGIS128_BLOCK_SIZE);
+		kernel_fpu_begin();
 	}
 
 	if (walk->nbytes) {
 		if (enc)
 			aegis128_aesni_enc_tail(state, walk->src.virt.addr,
@@ -129,11 +131,13 @@ crypto_aegis128_aesni_process_crypt(struct aegis_state *state,
 						walk->nbytes);
 		else
 			aegis128_aesni_dec_tail(state, walk->src.virt.addr,
 						walk->dst.virt.addr,
 						walk->nbytes);
+		kernel_fpu_end();
 		skcipher_walk_done(walk, 0);
+		kernel_fpu_begin();
 	}
 }
 
 static struct aegis_ctx *crypto_aegis128_aesni_ctx(struct crypto_aead *aead)
 {
@@ -174,13 +178,13 @@ crypto_aegis128_aesni_crypt(struct aead_request *req,
 	struct aegis_ctx *ctx = crypto_aegis128_aesni_ctx(tfm);
 	struct skcipher_walk walk;
 	struct aegis_state state;
 
 	if (enc)
-		skcipher_walk_aead_encrypt(&walk, req, true);
+		skcipher_walk_aead_encrypt(&walk, req, false);
 	else
-		skcipher_walk_aead_decrypt(&walk, req, true);
+		skcipher_walk_aead_decrypt(&walk, req, false);
 
 	kernel_fpu_begin();
 
 	aegis128_aesni_init(&state, &ctx->key, req->iv);
 	crypto_aegis128_aesni_process_ad(&state, req->src, req->assoclen);
-- 
2.50.0