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device/dram/ddr4: Check spd_bytes_total and spd_bytes_used values

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The value stored to 'spd_bytes_total' is never read. Now it is fixed.
This is spotted using clang-tool v9.
Also add a check if spd_bytes_used and/or spd_bytes_total are reserved
and make sure that spd_bytes_used is not greater than spd_bytes_total.

Change-Id: I426a7e64cc4c0bcced91d03387e02c8d965a21dc
Signed-off-by: Elyes HAOUAS <ehaouas@noos.fr>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/35558
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
This commit is contained in:
Elyes HAOUAS 2019-09-24 14:24:45 +02:00 committed by Nico Huber
parent c1dc2d5e68
commit 2a0fbe34ba
1 changed files with 16 additions and 2 deletions
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18
src/device/dram/ddr4.c
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@ -111,17 +111,31 @@ int spd_decode_ddr4(dimm_attr *dimm, spd_raw_data spd)
return SPD_STATUS_INVALID;
}
spd_bytes_total = (spd[0] >> 4) & ((1 << 3) - 1);
spd_bytes_used = spd[0] & ((1 << 4) - 1);
spd_bytes_total = (spd[0] >> 4) & 0x7;
spd_bytes_used = spd[0] & 0xf;
if (!spd_bytes_total || !spd_bytes_used) {
printk(BIOS_ERR, "SPD failed basic sanity checks\n");
return SPD_STATUS_INVALID;
}
if (spd_bytes_total >= 3)
printk(BIOS_WARNING, "SPD Bytes Total value is reserved\n");
spd_bytes_total = 256 << (spd_bytes_total - 1);
if (spd_bytes_used > 4) {
printk(BIOS_ERR, "SPD Bytes Used value is reserved\n");
return SPD_STATUS_INVALID;
}
spd_bytes_used = spd_bytes_used_table[spd_bytes_used];
if (spd_bytes_used > spd_bytes_total) {
printk(BIOS_ERR, "SPD Bytes Used is greater than SPD Bytes Total\n");
return SPD_STATUS_INVALID;
}
/* Verify CRC of blocks that have them, do not step over 'used' length */
for (int i = 0; i < ARRAY_SIZE(spd_blocks); i++) {
/* this block is not checksumed */