diff options
| author | Hao Wu <wuhaotsh@google.com> | 2021-01-26 17:11:42 -0800 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2021-01-29 10:47:28 +0000 |
| commit | 1e5ce6e10a1deaec6044ba8ad75431e0424dbce9 (patch) | |
| tree | 6f2110eeb591c05111c4c95886f6d185956b99c0 /tests/qtest | |
| parent | daa726d92604b72650d86ada01935e03a909d4dd (diff) | |
hw/misc: Fix arith overflow in NPCM7XX PWM module
Fix potential overflow problem when calculating pwm_duty.
1. Ensure p->cmr and p->cnr to be from [0,65535], according to the
hardware specification.
2. Changed duty to uint32_t. However, since MAX_DUTY * (p->cmr+1)
can excceed UINT32_MAX, we convert them to uint64_t in computation
and converted them back to uint32_t.
(duty is guaranteed to be <= MAX_DUTY so it won't overflow.)
Fixes: CID 1442342
Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Doug Evans <dje@google.com>
Signed-off-by: Hao Wu <wuhaotsh@google.com>
Message-id: 20210127011142.2122790-1-wuhaotsh@google.com
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'tests/qtest')
| -rw-r--r-- | tests/qtest/npcm7xx_pwm-test.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/tests/qtest/npcm7xx_pwm-test.c b/tests/qtest/npcm7xx_pwm-test.c index 63557d2c06..3d82654b81 100644 --- a/tests/qtest/npcm7xx_pwm-test.c +++ b/tests/qtest/npcm7xx_pwm-test.c @@ -272,7 +272,7 @@ static uint64_t pwm_compute_freq(QTestState *qts, uint32_t ppr, uint32_t csr, static uint64_t pwm_compute_duty(uint32_t cnr, uint32_t cmr, bool inverted) { - uint64_t duty; + uint32_t duty; if (cnr == 0) { /* PWM is stopped. */ @@ -280,7 +280,7 @@ static uint64_t pwm_compute_duty(uint32_t cnr, uint32_t cmr, bool inverted) } else if (cmr >= cnr) { duty = MAX_DUTY; } else { - duty = MAX_DUTY * (cmr + 1) / (cnr + 1); + duty = (uint64_t)MAX_DUTY * (cmr + 1) / (cnr + 1); } if (inverted) { |