From ce8ca305b49b3e6f3c495c3fbc31665f4eb0b9fd Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Mon, 7 Jan 2019 15:15:59 -0800 Subject: [PATCH] crypto: x86/chacha20 - avoid sleeping with preemption disabled In chacha20-simd, clear the MAY_SLEEP flag in the blkcipher_desc to prevent sleeping with preemption disabled, under kernel_fpu_begin(). This was fixed upstream incidentally by a large refactoring, commit 9ae433bc79f9 ("crypto: chacha20 - convert generic and x86 versions to skcipher"). But syzkaller easily trips over this when running on older kernels, as it's easily reachable via AF_ALG. Therefore, this patch makes the minimal fix for older kernels. Fixes: c9320b6dcb89 ("crypto: chacha20 - Add a SSSE3 SIMD variant for x86_64") Cc: linux-crypto@vger.kernel.org Cc: Martin Willi Signed-off-by: Eric Biggers Acked-by: Ard Biesheuvel Signed-off-by: Greg Kroah-Hartman --- arch/x86/crypto/chacha20_glue.c | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/x86/crypto/chacha20_glue.c b/arch/x86/crypto/chacha20_glue.c index f910d1d449f0..0a5fedf43bdc 100644 --- a/arch/x86/crypto/chacha20_glue.c +++ b/arch/x86/crypto/chacha20_glue.c @@ -77,6 +77,7 @@ static int chacha20_simd(struct blkcipher_desc *desc, struct scatterlist *dst, blkcipher_walk_init(&walk, dst, src, nbytes); err = blkcipher_walk_virt_block(desc, &walk, CHACHA20_BLOCK_SIZE); + desc->flags &= ~CRYPTO_TFM_REQ_MAY_SLEEP; crypto_chacha20_init(state, crypto_blkcipher_ctx(desc->tfm), walk.iv); -- 2.20.1