[PATCH 4.4.y] crypto: vmx - Fix sleep-in-atomic bugs

[Ondrej Mosnacek]

On Mon, Sep 10, 2018 at 9:42 AM Ondrej Mosnacek <omosnace at redhat.com> wrote:
> commit 0522236d4f9c5ab2e79889cb020d1acbe5da416e upstream.
>
> Conflicts:
>   drivers/crypto/vmx/
>     aes_cbc.c - adapted enable/disable calls to v4.4 state
>     aes_xts.c - did not exist yet in v4.4
>
> 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 at vger.kernel.org
> Signed-off-by: Ondrej Mosnacek <omosnace at redhat.com>
> Signed-off-by: Herbert Xu <herbert at gondor.apana.org.au>
> Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>

Whoops, sorry about that last Signed-off-by, I cherry-picked from
another stable commit and forgot to edit it out...

> ---
>  drivers/crypto/vmx/aes_cbc.c | 30 ++++++++++++++----------------
>  1 file changed, 14 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/crypto/vmx/aes_cbc.c b/drivers/crypto/vmx/aes_cbc.c
> index 9506e8693c81..d8ef1147b344 100644
> --- a/drivers/crypto/vmx/aes_cbc.c
> +++ b/drivers/crypto/vmx/aes_cbc.c
> @@ -111,24 +111,23 @@ static int p8_aes_cbc_encrypt(struct blkcipher_desc *desc,
>                 ret = crypto_blkcipher_encrypt(&fallback_desc, dst, src,
>                                                nbytes);
>         } else {
> -               preempt_disable();
> -               pagefault_disable();
> -               enable_kernel_altivec();
> -               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();
> +                       enable_kernel_altivec();
>                         aes_p8_cbc_encrypt(walk.src.virt.addr,
>                                            walk.dst.virt.addr,
>                                            nbytes & AES_BLOCK_MASK,
>                                            &ctx->enc_key, walk.iv, 1);
> +                       pagefault_enable();
> +                       preempt_enable();
> +
>                         nbytes &= AES_BLOCK_SIZE - 1;
>                         ret = blkcipher_walk_done(desc, &walk, nbytes);
>                 }
> -
> -               pagefault_enable();
> -               preempt_enable();
>         }
>
>         return ret;
> @@ -152,24 +151,23 @@ static int p8_aes_cbc_decrypt(struct blkcipher_desc *desc,
>                 ret = crypto_blkcipher_decrypt(&fallback_desc, dst, src,
>                                                nbytes);
>         } else {
> -               preempt_disable();
> -               pagefault_disable();
> -               enable_kernel_altivec();
> -               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();
> +                       enable_kernel_altivec();
>                         aes_p8_cbc_encrypt(walk.src.virt.addr,
>                                            walk.dst.virt.addr,
>                                            nbytes & AES_BLOCK_MASK,
>                                            &ctx->dec_key, walk.iv, 0);
> +                       pagefault_enable();
> +                       preempt_enable();
> +
>                         nbytes &= AES_BLOCK_SIZE - 1;
>                         ret = blkcipher_walk_done(desc, &walk, nbytes);
>                 }
> -
> -               pagefault_enable();
> -               preempt_enable();
>         }
>
>         return ret;
> --
> 2.17.1
>


-- 
Ondrej Mosnacek <omosnace at redhat dot com>
Associate Software Engineer, Security Technologies
Red Hat, Inc.