On Fri, 26 Apr 2019 23:54:58 +0200 Eugeniu Rosca roscaeugeniu@gmail.com wrote:
The random uuid values (enabled via CONFIG_RANDOM_UUID=y) on our platform are always the same. Below is consistent on each cold boot:
=> ### reach U-Boot prompt => setenv uuid_gpt_misc => gpt verify mmc 1 $partitions Verify GPT: success! => print uuid_gpt_misc uuid_gpt_misc=d117f98e-6f2c-d04b-a5b2-331a19f91cb2 => setenv uuid_gpt_misc => gpt verify mmc 1 $partitions Verify GPT: success! => print uuid_gpt_misc uuid_gpt_misc=ad5ec4b6-2d9f-8544-9417-fe3bd1c9b1b3
While the uuids do change on every 'gpt {write,verify}' command, the values appear to be taken from the same pool, in the same order.
As a user, I expect a trully random uuid value in the above example. Otherwise, system/RFS designers and OS people might assume they have a reliable/consistent uuid passed by the bootloader, while the truth is U-Boot simply lacks entropy to generate a random string.
Let's use get_timer() to update the seed, same as done in commit da384a9d7628 ("net: rename and refactor eth_rand_ethaddr() function").
Signed-off-by: Eugeniu Rosca erosca@de.adit-jv.com
lib/uuid.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/lib/uuid.c b/lib/uuid.c index fa20ee39fc32..8a82cb234b88 100644 --- a/lib/uuid.c +++ b/lib/uuid.c @@ -238,6 +238,8 @@ void gen_rand_uuid(unsigned char *uuid_bin) unsigned int *ptr = (unsigned int *)&uuid; int i;
- srand(get_timer(0));
- /* Set all fields randomly */ for (i = 0; i < sizeof(struct uuid) / sizeof(*ptr); i++) *(ptr + i) = cpu_to_be32(rand());
Reviewed-by: Lukasz Majewski lukma@denx.de
Best regards,
Lukasz Majewski
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