Re: [PATCH v2 01/20] rockchip: avoid out-of-bounds when computing cpuid

[Dragan Simic]

On 2024-02-09 10:49, Quentin Schulz wrote:

From: Quentin Schulz <quentin.sch...@theobroma-systems.com>

The expected length of the cpuid, as passed with cpuid_length,

determines the size of cpuid_str string. Therefore, care should be taken

to make sure nothing is accessing data out-of-bounds.

Instead of using hardcoded values, derive them from cpuid_length.

Cc: Quentin Schulz <foss+ub...@0leil.net>
Reviewed-by: Kever Yang <kever.y...@rock-chips.com>
Signed-off-by: Quentin Schulz <quentin.sch...@theobroma-systems.com>

Looking good to me.

Reviewed-by: Dragan Simic <dsi...@manjaro.org>

---
 arch/arm/mach-rockchip/misc.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mach-rockchip/misc.c b/arch/arm/mach-rockchip/misc.c

index 7d03f0c2b67..15397cff009 100644
--- a/arch/arm/mach-rockchip/misc.c
+++ b/arch/arm/mach-rockchip/misc.c
@@ -102,7 +102,7 @@ int rockchip_cpuid_set(const u8 *cpuid, const u32
cpuid_length)
        int i;

        memset(cpuid_str, 0, sizeof(cpuid_str));
-       for (i = 0; i < 16; i++)
+       for (i = 0; i < cpuid_length; i++)
                sprintf(&cpuid_str[i * 2], "%02x", cpuid[i]);

        debug("cpuid: %s\n", cpuid_str);
@@ -111,13 +111,13 @@ int rockchip_cpuid_set(const u8 *cpuid, const
u32 cpuid_length)
         * Mix the cpuid bytes using the same rules as in
         *   ${linux}/drivers/soc/rockchip/rockchip-cpuinfo.c
         */
-       for (i = 0; i < 8; i++) {
+       for (i = 0; i < cpuid_length / 2; i++) {
                low[i] = cpuid[1 + (i << 1)];
                high[i] = cpuid[i << 1];
        }

-       serialno = crc32_no_comp(0, low, 8);
-       serialno |= (u64)crc32_no_comp(serialno, high, 8) << 32;
+       serialno = crc32_no_comp(0, low, cpuid_length / 2);

+ serialno |= (u64)crc32_no_comp(serialno, high, cpuid_length / 2) << 32;

        snprintf(serialno_str, sizeof(serialno_str), "%016llx", serialno);

        oldid = env_get("cpuid#");