Re: [PATCH] crypto: vmx - Fix sleep-in-atomic bugs

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CC: Paulo Flabiano Smorigo <pfsmorigo@xxxxxxxxxxxxxxxxxx>,
linuxppc-dev@xxxxxxxxxxxxxxxx

(Sorry, sent this before reading new e-mails in the thread...)

ut 21. 8. 2018 o 17:18 Ondrej Mosnacek <omosnace@xxxxxxxxxx> napísal(a):
>
> This patch fixes sleep-in-atomic bugs in AES-CBC and AES-XTS VMX
> implementations. The problem is that the blkcipher_* functions should
> not be called in atomic context.
>
> The bugs can be reproduced via the AF_ALG interface by trying to
> encrypt/decrypt sufficiently large buffers (at least 64 KiB) using the
> VMX implementations of 'cbc(aes)' or 'xts(aes)'. Such operations then
> trigger BUG in crypto_yield():
>
> [  891.863680] BUG: sleeping function called from invalid context at include/crypto/algapi.h:424
> [  891.864622] in_atomic(): 1, irqs_disabled(): 0, pid: 12347, name: kcapi-enc
> [  891.864739] 1 lock held by kcapi-enc/12347:
> [  891.864811]  #0: 00000000f5d42c46 (sk_lock-AF_ALG){+.+.}, at: skcipher_recvmsg+0x50/0x530
> [  891.865076] CPU: 5 PID: 12347 Comm: kcapi-enc Not tainted 4.19.0-0.rc0.git3.1.fc30.ppc64le #1
> [  891.865251] Call Trace:
> [  891.865340] [c0000003387578c0] [c000000000d67ea4] dump_stack+0xe8/0x164 (unreliable)
> [  891.865511] [c000000338757910] [c000000000172a58] ___might_sleep+0x2f8/0x310
> [  891.865679] [c000000338757990] [c0000000006bff74] blkcipher_walk_done+0x374/0x4a0
> [  891.865825] [c0000003387579e0] [d000000007e73e70] p8_aes_cbc_encrypt+0x1c8/0x260 [vmx_crypto]
> [  891.865993] [c000000338757ad0] [c0000000006c0ee0] skcipher_encrypt_blkcipher+0x60/0x80
> [  891.866128] [c000000338757b10] [c0000000006ec504] skcipher_recvmsg+0x424/0x530
> [  891.866283] [c000000338757bd0] [c000000000b00654] sock_recvmsg+0x74/0xa0
> [  891.866403] [c000000338757c10] [c000000000b00f64] ___sys_recvmsg+0xf4/0x2f0
> [  891.866515] [c000000338757d90] [c000000000b02bb8] __sys_recvmsg+0x68/0xe0
> [  891.866631] [c000000338757e30] [c00000000000bbe4] system_call+0x5c/0x70
>
> Fixes: 8c755ace357c ("crypto: vmx - Adding CBC routines for VMX module")
> Fixes: c07f5d3da643 ("crypto: vmx - Adding support for XTS")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx>
> ---
> This patch should fix the issue, but I didn't test it. (I'll see if I
> can find some time tomorrow to try and recompile the kernel on a PPC
> machine... in the meantime please review :)
>
>  drivers/crypto/vmx/aes_cbc.c | 30 ++++++++++++++----------------
>  drivers/crypto/vmx/aes_xts.c | 19 ++++++++++++-------
>  2 files changed, 26 insertions(+), 23 deletions(-)
>
> diff --git a/drivers/crypto/vmx/aes_cbc.c b/drivers/crypto/vmx/aes_cbc.c
> index 5285ece4f33a..b71895871be3 100644
> --- a/drivers/crypto/vmx/aes_cbc.c
> +++ b/drivers/crypto/vmx/aes_cbc.c
> @@ -107,24 +107,23 @@ static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
>                 ret = crypto_skcipher_encrypt(req);
>                 skcipher_request_zero(req);
>         } else {
> -               preempt_disable();
> -               pagefault_disable();
> -               enable_kernel_vsx();
> -
>                 blkcipher_walk_init(&walk, dst, src, nbytes);
>                 ret = blkcipher_walk_virt(desc, &walk);
>                 while ((nbytes = walk.nbytes)) {
> +                       preempt_disable();
> +                       pagefault_disable();
> +                       enable_kernel_vsx();
>                         aes_p8_cbc_encrypt(walk.src.virt.addr,
>                                            walk.dst.virt.addr,
>                                            nbytes & AES_BLOCK_MASK,
>                                            &ctx->enc_key, walk.iv, 1);
> +                       disable_kernel_vsx();
> +                       pagefault_enable();
> +                       preempt_enable();
> +
>                         nbytes &= AES_BLOCK_SIZE - 1;
>                         ret = blkcipher_walk_done(desc, &walk, nbytes);
>                 }
> -
> -               disable_kernel_vsx();
> -               pagefault_enable();
> -               preempt_enable();
>         }
>
>         return ret;
> @@ -147,24 +146,23 @@ static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
>                 ret = crypto_skcipher_decrypt(req);
>                 skcipher_request_zero(req);
>         } else {
> -               preempt_disable();
> -               pagefault_disable();
> -               enable_kernel_vsx();
> -
>                 blkcipher_walk_init(&walk, dst, src, nbytes);
>                 ret = blkcipher_walk_virt(desc, &walk);
>                 while ((nbytes = walk.nbytes)) {
> +                       preempt_disable();
> +                       pagefault_disable();
> +                       enable_kernel_vsx();
>                         aes_p8_cbc_encrypt(walk.src.virt.addr,
>                                            walk.dst.virt.addr,
>                                            nbytes & AES_BLOCK_MASK,
>                                            &ctx->dec_key, walk.iv, 0);
> +                       disable_kernel_vsx();
> +                       pagefault_enable();
> +                       preempt_enable();
> +
>                         nbytes &= AES_BLOCK_SIZE - 1;
>                         ret = blkcipher_walk_done(desc, &walk, nbytes);
>                 }
> -
> -               disable_kernel_vsx();
> -               pagefault_enable();
> -               preempt_enable();
>         }
>
>         return ret;
> diff --git a/drivers/crypto/vmx/aes_xts.c b/drivers/crypto/vmx/aes_xts.c
> index 8bd9aff0f55f..016ef52390c9 100644
> --- a/drivers/crypto/vmx/aes_xts.c
> +++ b/drivers/crypto/vmx/aes_xts.c
> @@ -116,13 +116,14 @@ static int p8_aes_xts_crypt(struct blkcipher_desc *desc,
>                 ret = enc? crypto_skcipher_encrypt(req) : crypto_skcipher_decrypt(req);
>                 skcipher_request_zero(req);
>         } else {
> +               blkcipher_walk_init(&walk, dst, src, nbytes);
> +
> +               ret = blkcipher_walk_virt(desc, &walk);
> +
>                 preempt_disable();
>                 pagefault_disable();
>                 enable_kernel_vsx();
>
> -               blkcipher_walk_init(&walk, dst, src, nbytes);
> -
> -               ret = blkcipher_walk_virt(desc, &walk);
>                 iv = walk.iv;
>                 memset(tweak, 0, AES_BLOCK_SIZE);
>                 aes_p8_encrypt(iv, tweak, &ctx->tweak_key);
> @@ -135,13 +136,17 @@ static int p8_aes_xts_crypt(struct blkcipher_desc *desc,
>                                 aes_p8_xts_decrypt(walk.src.virt.addr, walk.dst.virt.addr,
>                                                 nbytes & AES_BLOCK_MASK, &ctx->dec_key, NULL, tweak);
>
> +                       disable_kernel_vsx();
> +                       pagefault_enable();
> +                       preempt_enable();
> +
>                         nbytes &= AES_BLOCK_SIZE - 1;
>                         ret = blkcipher_walk_done(desc, &walk, nbytes);
> -               }
>
> -               disable_kernel_vsx();
> -               pagefault_enable();
> -               preempt_enable();
> +                       preempt_disable();
> +                       pagefault_disable();
> +                       enable_kernel_vsx();
> +               }
>         }
>         return ret;
>  }
> --
> 2.17.1
>




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