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i2c: lpi2c: Avoid calling clk_get_rate during transfer 

JIRA: https://issues.redhat.com/browse/RHEL-48206
CVE: CVE-2024-40965

commit 4268254a39484fc11ba991ae148bacbe75d9cc0a
Author: Alexander Stein <alexander.stein@ew.tq-group.com>
Date:   Mon Apr 22 13:36:29 2024 +0200

    i2c: lpi2c: Avoid calling clk_get_rate during transfer

    Instead of repeatedly calling clk_get_rate for each transfer, lock
    the clock rate and cache the value.
    A deadlock has been observed while adding tlv320aic32x4 audio codec to
    the system. When this clock provider adds its clock, the clk mutex is
    locked already, it needs to access i2c, which in return needs the mutex
    for clk_get_rate as well.

    Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
    Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
    Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
    Signed-off-by: Andi Shyti <andi.shyti@kernel.org>

Signed-off-by: David Arcari <darcari@redhat.com>
This commit is contained in:
David Arcari 2024-07-17 13:10:50 -04:00
parent 035c324faa
commit 0977a3abd1
1 changed files with 16 additions and 3 deletions
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19
drivers/i2c/busses/i2c-imx-lpi2c.c
View File

@ -100,6 +100,7 @@ struct lpi2c_imx_struct {
__u8 *rx_buf;
__u8 *tx_buf;
struct completion complete;
unsigned long rate_per;
unsigned int msglen;
unsigned int delivered;
unsigned int block_data;
@ -208,9 +209,7 @@ static int lpi2c_imx_config(struct lpi2c_imx_struct *lpi2c_imx)
lpi2c_imx_set_mode(lpi2c_imx);
clk_rate = clk_get_rate(lpi2c_imx->clks[0].clk);
if (!clk_rate)
return -EINVAL;
clk_rate = lpi2c_imx->rate_per;
if (lpi2c_imx->mode == HS || lpi2c_imx->mode == ULTRA_FAST)
filt = 0;
@ -597,6 +596,20 @@ static int lpi2c_imx_probe(struct platform_device *pdev)
if (ret)
return ret;
/*
* Lock the parent clock rate to avoid getting parent clock upon
* each transfer
*/
ret = devm_clk_rate_exclusive_get(&pdev->dev, lpi2c_imx->clks[0].clk);
if (ret)
return dev_err_probe(&pdev->dev, ret,
"can't lock I2C peripheral clock rate\n");
lpi2c_imx->rate_per = clk_get_rate(lpi2c_imx->clks[0].clk);
if (!lpi2c_imx->rate_per)
return dev_err_probe(&pdev->dev, -EINVAL,
"can't get I2C peripheral clock rate\n");
pm_runtime_set_autosuspend_delay(&pdev->dev, I2C_PM_TIMEOUT);
pm_runtime_use_autosuspend(&pdev->dev);
pm_runtime_get_noresume(&pdev->dev);