[lkml]   [2019]   [Jan]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 4.9 42/63] crypto: x86/chacha20 - avoid sleeping with preemption disabled
4.9-stable review patch.  If anyone has any objections, please let me know.


From: Eric Biggers <>

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: 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(+)

--- a/arch/x86/crypto/chacha20_glue.c
+++ b/arch/x86/crypto/chacha20_glue.c
@@ -77,6 +77,7 @@ static int chacha20_simd(struct blkciphe

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);

 \ /
  Last update: 2019-01-11 16:08    [W:0.237 / U:3.000 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site