linux-kernel - [PATCH] crypto: caam - fix endless loop when DECO acquire fails

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Date:   Mon, 5 Feb 2018 11:15:52 +0200
From:   Horia Geantă <horia.geanta@....com>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        Bryan O'Donoghue <pure.logic@...us-software.ie>,
        Auer Lukas <lukas.auer@...ec.fraunhofer.de>
CC:     "David S. Miller" <davem@...emloft.net>,
        Aymen Sghaier <aymen.sghaier@....com>,
        Alexandru Porosanu <alexandru.porosanu@....com>,
        Fabio Estevam <fabio.estevam@....com>,
        Peng Fan <peng.fan@....com>, Rui Silva <rui.silva@...aro.org>,
        Ryan Harkin <ryan.harkin@...aro.org>,
        <linux-crypto@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] crypto: caam - fix endless loop when DECO acquire fails

In case DECO0 cannot be acquired - i.e. run_descriptor_deco0() fails
with -ENODEV, caam_probe() enters an endless loop:

run_descriptor_deco0
	ret -ENODEV
	-> instantiate_rng
		-ENODEV, overwritten by -EAGAIN
		ret -EAGAIN
		-> caam_probe
			-EAGAIN results in endless loop

It turns out the error path in instantiate_rng() is incorrect,
the checks are done in the wrong order.

Cc: <stable@...r.kernel.org> # 3.13+
Fixes: 1005bccd7a4a6 ("crypto: caam - enable instantiation of all RNG4 state handles")
Reported-by: Bryan O'Donoghue <pure.logic@...us-software.ie>
Suggested-by: Auer Lukas <lukas.auer@...ec.fraunhofer.de>
Signed-off-by: Horia Geantă <horia.geanta@....com>
---
 drivers/crypto/caam/ctrl.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/crypto/caam/ctrl.c b/drivers/crypto/caam/ctrl.c
index 75d280cb2dc0..e843cf410373 100644
--- a/drivers/crypto/caam/ctrl.c
+++ b/drivers/crypto/caam/ctrl.c
@@ -228,12 +228,16 @@ static int instantiate_rng(struct device *ctrldev, int state_handle_mask,
 		 * without any error (HW optimizations for later
 		 * CAAM eras), then try again.
 		 */
+		if (ret)
+			break;
+
 		rdsta_val = rd_reg32(&ctrl->r4tst[0].rdsta) & RDSTA_IFMASK;
 		if ((status && status != JRSTA_SSRC_JUMP_HALT_CC) ||
-		    !(rdsta_val & (1 << sh_idx)))
+		    !(rdsta_val & (1 << sh_idx))) {
 			ret = -EAGAIN;
-		if (ret)
 			break;
+		}
+
 		dev_info(ctrldev, "Instantiated RNG4 SH%d\n", sh_idx);
 		/* Clear the contents before recreating the descriptor */
 		memset(desc, 0x00, CAAM_CMD_SZ * 7);
-- 
2.12.0.264.gd6db3f216544