Re: [PATCH] crypto/testmgr: fix skcipher test with CONFIG_VMAP_STACK

[Ard Biesheuvel]

On Fri, 7 Dec 2018 at 18:33, Christophe Leroy <christophe.leroy@xxxxxx> wrote:
>
> [    2.364486] WARNING: CPU: 0 PID: 60 at ./arch/powerpc/include/asm/io.h:837 dma_nommu_map_page+0x44/0xd4
> [    2.373579] CPU: 0 PID: 60 Comm: cryptomgr_test Tainted: G        W         4.20.0-rc5-00560-g6bfb52e23a00-dirty #531
> [    2.384740] NIP:  c000c540 LR: c000c584 CTR: 00000000
> [    2.389743] REGS: c95abab0 TRAP: 0700   Tainted: G        W          (4.20.0-rc5-00560-g6bfb52e23a00-dirty)
> [    2.400042] MSR:  00029032 <EE,ME,IR,DR,RI>  CR: 24042204  XER: 00000000
> [    2.406669]
> [    2.406669] GPR00: c02f2244 c95abb60 c6262990 c95abd80 0000256a 00000001 00000001 00000001
> [    2.406669] GPR08: 00000000 00002000 00000010 00000010 24042202 00000000 00000100 c95abd88
> [    2.406669] GPR16: 00000000 c05569d4 00000001 00000010 c95abc88 c0615664 00000004 00000000
> [    2.406669] GPR24: 00000010 c95abc88 c95abc88 00000000 c61ae210 c7ff6d40 c61ae210 00003d68
> [    2.441559] NIP [c000c540] dma_nommu_map_page+0x44/0xd4
> [    2.446720] LR [c000c584] dma_nommu_map_page+0x88/0xd4
> [    2.451762] Call Trace:
> [    2.454195] [c95abb60] [82000808] 0x82000808 (unreliable)
> [    2.459572] [c95abb80] [c02f2244] talitos_edesc_alloc+0xbc/0x3c8
> [    2.465493] [c95abbb0] [c02f2600] ablkcipher_edesc_alloc+0x4c/0x5c
> [    2.471606] [c95abbd0] [c02f4ed0] ablkcipher_encrypt+0x20/0x64
> [    2.477389] [c95abbe0] [c02023b0] __test_skcipher+0x4bc/0xa08
> [    2.483049] [c95abe00] [c0204b60] test_skcipher+0x2c/0xcc
> [    2.488385] [c95abe20] [c0204c48] alg_test_skcipher+0x48/0xbc
> [    2.494064] [c95abe40] [c0205cec] alg_test+0x164/0x2e8
> [    2.499142] [c95abf00] [c0200dec] cryptomgr_test+0x48/0x50
> [    2.504558] [c95abf10] [c0039ff4] kthread+0xe4/0x110
> [    2.509471] [c95abf40] [c000e1d0] ret_from_kernel_thread+0x14/0x1c
> [    2.515532] Instruction dump:
> [    2.518468] 7c7e1b78 7c9d2378 7cbf2b78 41820054 3d20c076 8089c200 3d20c076 7c84e850
> [    2.526127] 8129c204 7c842e70 7f844840 419c0008 <0fe00000> 2f9e0000 54847022 7c84fa14
> [    2.533960] ---[ end trace bf78d94af73fe3b8 ]---
> [    2.539123] talitos ff020000.crypto: master data transfer error
> [    2.544775] talitos ff020000.crypto: TEA error: ISR 0x20000000_00000040
> [    2.551625] alg: skcipher: encryption failed on test 1 for ecb-aes-talitos: ret=22
>
> IV cannot be on stack when CONFIG_VMAP_STACK is selected because the stack
> cannot be DMA mapped anymore.
>
> This patch allocates it with kmalloc()
>

This looks like a driver bug to me. Other accelerators in
drivers/crypto all take a copy of the IV before mapping it for DMA, so
it would be better if talitos did the same.

> Fixes: da7f033ddc9f ("crypto: cryptomgr - Add test infrastructure")
> Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxx>
> ---
>  crypto/testmgr.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index b1f79c6bf409..eea498f9030d 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c
> @@ -1112,12 +1112,16 @@ static int __test_skcipher(struct crypto_skcipher *tfm, int enc,
>         struct crypto_wait wait;
>         const char *input, *result;
>         void *data;
> -       char iv[MAX_IVLEN];
> +       char *iv;
>         char *xbuf[XBUFSIZE];
>         char *xoutbuf[XBUFSIZE];
>         int ret = -ENOMEM;
>         unsigned int ivsize = crypto_skcipher_ivsize(tfm);
>
> +       iv = kmalloc(MAX_IVLEN, GFP_KERNEL | GFP_DMA);
> +       if (!iv)
> +               goto out_noiv;
> +
>         if (testmgr_alloc_buf(xbuf))
>                 goto out_nobuf;
>
> @@ -1339,6 +1343,8 @@ static int __test_skcipher(struct crypto_skcipher *tfm, int enc,
>  out_nooutbuf:
>         testmgr_free_buf(xbuf);
>  out_nobuf:
> +       kfree(iv);
> +out_noiv:
>         return ret;
>  }
>
> --
> 2.13.3
>