On Tue, 8 Jan 2019 at 00:16, Eric Biggers ebiggers@kernel.org wrote:
From: Eric Biggers ebiggers@google.com
Hi Greg, please consider applying this to 4.9-stable and 4.4-stable. It's a minimal fix for a bug that was fixed incidentally by a large refactoring in v4.11.
8------------------------------------------------------8<
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 martin@strongswan.org Cc: Ard Biesheuvel ard.biesheuvel@linaro.org Signed-off-by: Eric Biggers ebiggers@google.com
Acked-by: Ard Biesheuvel ard.biesheuvel@linaro.org
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 f910d1d449f00..0a5fedf43bdc8 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);-- 2.20.1.97.g81188d93c3-goog