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random: vDSO: avoid call to out of line memset()

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With the current implementation, __cvdso_getrandom_data() calls
memset() on certain architectures, which is unexpected in the VDSO.

Rather than providing a memset(), simply rewrite opaque data
initialization to avoid memset().

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
This commit is contained in:
Christophe Leroy 2024-08-22 09:13:13 +02:00 committed by Jason A. Donenfeld
parent 81723e3ac3
commit b7bad082e1
1 changed files with 7 additions and 5 deletions
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12
lib/vdso/getrandom.c
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@ -3,6 +3,7 @@
* Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/
#include <linux/array_size.h>
#include <linux/cache.h>
#include <linux/kernel.h>
#include <linux/time64.h>
@ -73,11 +74,12 @@ __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_
u32 counter[2] = { 0 };
if (unlikely(opaque_len == ~0UL && !buffer && !len && !flags)) {
*(struct vgetrandom_opaque_params *)opaque_state = (struct vgetrandom_opaque_params) {
.size_of_opaque_state = sizeof(*state),
.mmap_prot = PROT_READ | PROT_WRITE,
.mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS
};
struct vgetrandom_opaque_params *params = opaque_state;
params->size_of_opaque_state = sizeof(*state);
params->mmap_prot = PROT_READ | PROT_WRITE;
params->mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS;
for (size_t i = 0; i < ARRAY_SIZE(params->reserved); ++i)
params->reserved[i] = 0;
return 0;
}