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crypto: x86/chacha20 - avoid sleeping with preemption disabled

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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>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Biggers 2019-01-07 15:15:59 -08:00 committed by Greg Kroah-Hartman
parent f12e01b3c6
commit ce8ca305b4
1 changed files with 1 additions and 0 deletions
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arch/x86/crypto/chacha20_glue.c
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@ -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);