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x86: reinitialize RNG seed on system reboot

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Since this is read from fw_cfg on each boot, the kernel zeroing it out
alone is insufficient to prevent it from being used twice. And indeed on
reboot we always want a new seed, not the old one. So re-fill it in this
circumstance.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Message-Id: <20220921093134.2936487-3-Jason@zx2c4.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jason A. Donenfeld 2022-09-21 11:31:33 +02:00 committed by Paolo Bonzini
parent eebb38a563
commit 763a2828bf
1 changed files with 7 additions and 0 deletions
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7
hw/i386/x86.c
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@ -783,6 +783,12 @@ static void reset_setup_data(void *opaque)
stq_p(fixup->pos, fixup->orig_val);
}
static void reset_rng_seed(void *opaque)
{
SetupData *setup_data = opaque;
qemu_guest_getrandom_nofail(setup_data->data, le32_to_cpu(setup_data->len));
}
void x86_load_linux(X86MachineState *x86ms,
FWCfgState *fw_cfg,
int acpi_data_size,
@ -1105,6 +1111,7 @@ void x86_load_linux(X86MachineState *x86ms,
setup_data->type = cpu_to_le32(SETUP_RNG_SEED);
setup_data->len = cpu_to_le32(RNG_SEED_LENGTH);
qemu_guest_getrandom_nofail(setup_data->data, RNG_SEED_LENGTH);
qemu_register_reset(reset_rng_seed, setup_data);
}
fw_cfg_add_i32(fw_cfg, FW_CFG_KERNEL_ADDR, prot_addr);