Message ID | 20200330173801.GA9199@SDF.ORG (mailing list archive) |
---|---|
State | Mainlined |
Commit | 99ee28d99607d15c6b88c4a9b9fb4a9f0ebf598c |
Headers | show |
Series | [v2] arm64: kexec_file: Avoid temp buffer for RNG seed | expand |
On Mon, 30 Mar 2020 17:38:01 +0000, George Spelvin wrote: > After using get_random_bytes(), you want to wipe the buffer > afterward so the seed remains secret. > > In this case, we can eliminate the temporary buffer entirely. > fdt_setprop_placeholder() returns a pointer to the property value > buffer, allowing us to put the random data directly in there without > using a temporary buffer at all. Faster and less stack all in one. Applied to arm64 (for-next/misc), thanks! [1/1] arm64: kexec_file: Avoid temp buffer for RNG seed https://git.kernel.org/arm64/c/99ee28d99607 Cheers,
diff --git a/arch/arm64/kernel/machine_kexec_file.c b/arch/arm64/kernel/machine_kexec_file.c index 7b08bf9499b6b..69e25bb96e3fb 100644 --- a/arch/arm64/kernel/machine_kexec_file.c +++ b/arch/arm64/kernel/machine_kexec_file.c @@ -106,12 +106,12 @@ static int setup_dtb(struct kimage *image, /* add rng-seed */ if (rng_is_initialized()) { - u8 rng_seed[RNG_SEED_SIZE]; - get_random_bytes(rng_seed, RNG_SEED_SIZE); - ret = fdt_setprop(dtb, off, FDT_PROP_RNG_SEED, rng_seed, - RNG_SEED_SIZE); + void *rng_seed; + ret = fdt_setprop_placeholder(dtb, off, FDT_PROP_RNG_SEED, + RNG_SEED_SIZE, &rng_seed); if (ret) goto out; + get_random_bytes(rng_seed, RNG_SEED_SIZE); } else { pr_notice("RNG is not initialised: omitting \"%s\" property\n", FDT_PROP_RNG_SEED);