2018-02-07 15:52:09

by Kamil Konieczny

Subject: [PATCH v3] crypto: s5p-sss.c: Fix kernel Oops in AES-ECB mode

In AES-ECB mode crypt is done with key only, so any use of IV
can cause kernel Oops. Use IV only in AES-CBC and AES-CTR.

Signed-off-by: Kamil Konieczny <[email protected]>
Reported-by: Anand Moon <[email protected]>
Reviewed-by: Krzysztof Kozlowski <[email protected]>
Tested-by: Anand Moon <[email protected]>
Cc: [email protected] # can be applied after commit 8f9702aad138

---
version 3:
Change commit message: drop 'Fixes: 8f9702aad138' as the error was
introduced earlier.

version 2:
Change commit message.

Tested on Odroid XU4/HC1, kernel 4.15 with following command:

fallocate -l 128MiB /tmp/test.bin
dd if=/dev/urandom of=/tmp/testkey.key bs=128 count=1
sync
cryptsetup luksFormat --debug -q -d /tmp/testkey.key \
--cipher aes-cbc-essiv:sha256 -h sha256 -s 128 /tmp/test.bin

The original report by Anand Moon:
https://www.spinics.net/lists/linux-crypto/msg31180.html

Oops reproduced with cryptsetup 2.0.0, kernel 4.15,
in .config in crypto API ECB support was turned off, and s5p-sss AES driver on.

cryptsetup is using aes-ecb and has req->info in aes_ctx set to 0x10,
which caused Oops:

[ 2078.683779] Internal error: Oops: 17 [#1] PREEMPT SMP ARM
[ 2078.689148] Modules linked in: algif_skcipher af_alg sd_mod sg
evdev uas usb_storage scsi_mod gpio_keys fbtft(C) spidev spi_s3c64xx
ipv6
[ 2078.701377] CPU: 1 PID: 15 Comm: ksoftirqd/1 Tainted: G C
4.15.0-rc9-xu4krck #1
[ 2078.709861] Hardware name: SAMSUNG EXYNOS (Flattened Device Tree)
[ 2078.715932] PC is at memcpy+0x80/0x330
[ 2078.719652] LR is at s5p_tasklet_cb+0x19c/0x328


drivers/crypto/s5p-sss.c | 12 +++++++++---
1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/crypto/s5p-sss.c b/drivers/crypto/s5p-sss.c
index 142c6020cec7..5c0496d1ed41 100644
--- a/drivers/crypto/s5p-sss.c
+++ b/drivers/crypto/s5p-sss.c
@@ -1926,15 +1926,21 @@ static void s5p_aes_crypt_start(struct s5p_aes_dev *dev, unsigned long mode)
uint32_t aes_control;
unsigned long flags;
int err;
+ u8 *iv;

aes_control = SSS_AES_KEY_CHANGE_MODE;
if (mode & FLAGS_AES_DECRYPT)
aes_control |= SSS_AES_MODE_DECRYPT;

- if ((mode & FLAGS_AES_MODE_MASK) == FLAGS_AES_CBC)
+ if ((mode & FLAGS_AES_MODE_MASK) == FLAGS_AES_CBC) {
aes_control |= SSS_AES_CHAIN_MODE_CBC;
- else if ((mode & FLAGS_AES_MODE_MASK) == FLAGS_AES_CTR)
+ iv = req->info;
+ } else if ((mode & FLAGS_AES_MODE_MASK) == FLAGS_AES_CTR) {
aes_control |= SSS_AES_CHAIN_MODE_CTR;
+ iv = req->info;
+ } else {
+ iv = NULL; /* AES_ECB */
+ }

if (dev->ctx->keylen == AES_KEYSIZE_192)
aes_control |= SSS_AES_KEY_SIZE_192;
@@ -1965,7 +1971,7 @@ static void s5p_aes_crypt_start(struct s5p_aes_dev *dev, unsigned long mode)
goto outdata_error;

SSS_AES_WRITE(dev, AES_CONTROL, aes_control);
- s5p_set_aes(dev, dev->ctx->aes_key, req->info, dev->ctx->keylen);
+ s5p_set_aes(dev, dev->ctx->aes_key, iv, dev->ctx->keylen);

s5p_set_dma_indata(dev, dev->sg_src);
s5p_set_dma_outdata(dev, dev->sg_dst);
--
2.16.0

2018-02-15 15:53:13

by Herbert Xu

Subject: Re: [PATCH v3] crypto: s5p-sss.c: Fix kernel Oops in AES-ECB mode

On Wed, Feb 07, 2018 at 04:52:09PM +0100, Kamil Konieczny wrote:
> In AES-ECB mode crypt is done with key only, so any use of IV
> can cause kernel Oops. Use IV only in AES-CBC and AES-CTR.
>
> Signed-off-by: Kamil Konieczny <[email protected]>
> Reported-by: Anand Moon <[email protected]>
> Reviewed-by: Krzysztof Kozlowski <[email protected]>
> Tested-by: Anand Moon <[email protected]>
> Cc: [email protected] # can be applied after commit 8f9702aad138
>
> ---
> version 3:
> Change commit message: drop 'Fixes: 8f9702aad138' as the error was
> introduced earlier.

Patch applied. Thanks.
--
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt