device/dram/ddr3.c: Check SPD byte before using as a divisor
The Medium Time Base (MTB) value is calculated by dividing one SPD
byte by another. Return an error if the divisor is zero before using
the value for division.
Found-by: Coverity Scan #1469303
Signed-off-by: Martin Roth <gaumless@gmail.com>
Change-Id: Ic0a70291c42b5c2d21d65de92487b2dd88609983
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78613
Reviewed-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Singer <service+coreboot-gerrit@felixsinger.de>
diff --git a/src/device/dram/ddr3.c b/src/device/dram/ddr3.c
index 9e11ab5..1fa3f4c 100644
--- a/src/device/dram/ddr3.c
+++ b/src/device/dram/ddr3.c
@@ -422,6 +422,8 @@
/* Medium Timebase =
* Medium Timebase (MTB) Dividend /
* Medium Timebase (MTB) Divisor */
+ if (spd[181] == 0) // Avoid dividing by zero.
+ return SPD_STATUS_INVALID;
mtb = (((u32)spd[180]) << 8) / spd[181];
dimm->dimms_per_channel = ((spd[178] >> 2) & 0x3) + 1;
@@ -437,6 +439,8 @@
/* Medium Timebase =
* Medium Timebase (MTB) Dividend /
* Medium Timebase (MTB) Divisor */
+ if (spd[183] == 0) // Avoid dividing by zero.
+ return SPD_STATUS_INVALID;
mtb = (((u32)spd[182]) << 8) / spd[183];
dimm->dimms_per_channel = ((spd[178] >> 4) & 0x3) + 1;