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authorJacob Garber <jgarber1@ualberta.ca>2019-07-22 13:31:38 -0600
committerPatrick Georgi <pgeorgi@google.com>2019-07-29 06:08:21 +0000
commit767c4b28998aff563c36e2f2000e4768b68add8f (patch)
tree6bfec62675992f5ecda676cec182b294638ddf59 /util/k8resdump
parent5592cfd5b3dc0478af5e9ddd65f8169214860575 (diff)
soc/intel/baytrail: Prevent unintended sign extensions
Consider the following assignment: u64 = s32 For positive values this is fine, but if the s32 is negative, it will be sign-extended in the conversion to a very large unsigned integer. This manifests itself in two ways in the following code: First, gpu_pipe{a,b}_port_select are defined as int, and can have the values 1 or 2. In the case when they have the value 2, the shift 2 << 30 will be a negative number, making it susceptible to the sign-extension problem above. Change these variables to something more reasonable like a uint8_t, which is unsigned. Second, in any bit shift, any variable with width less than an int will be implicitly promoted to an int before performing the bit shift. For example, the variable gpu_pipea_power_on_delay is a uint16_t, and if its highest bit is set, the shift gpu_pipea_power_on_delay << 16 will become negative, again introducing the above problem. To prevent this, cast all smaller variables to a u32 before the shift, which will prevent the implicit promotions and sign extensions. Change-Id: Ic5db6001504cefb501dee199590a0e961a15771b Signed-off-by: Jacob Garber <jgarber1@ualberta.ca> Found-by: Coverity CID 1229699, 1229700, 1229701, 1229702 Reviewed-on: https://review.coreboot.org/c/coreboot/+/34487 Reviewed-by: Angel Pons <th3fanbus@gmail.com> Reviewed-by: Alexander Couzens <lynxis@fe80.eu> Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
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