[PATCH v2 05/17] vdso: Avoid call to memset() by getrandom
From: Christophe Leroy <hidden>
Date: 2024-08-22 07:13:56
Also in:
linux-arch, linux-fsdevel, linux-kselftest, linux-mm, linux-trace-kernel, lkml
Subsystem:
generic vdso library, library code, the rest · Maintainers:
Andy Lutomirski, Thomas Gleixner, Vincenzo Frascino, Andrew Morton, Linus Torvalds
With the current implementation, __cvdso_getrandom_data() calls memset(), which is unexpected in the VDSO. Rewrite opaque data initialisation to avoid memset(). Signed-off-by: Christophe Leroy <redacted> --- lib/vdso/getrandom.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c
index cab153c5f9be..4a56f45141b4 100644
--- a/lib/vdso/getrandom.c
+++ b/lib/vdso/getrandom.c@@ -4,6 +4,7 @@ */ #include <linux/minmax.h> +#include <linux/array_size.h> #include <vdso/datapage.h> #include <vdso/getrandom.h> #include <vdso/unaligned.h>
@@ -74,11 +75,15 @@ __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; + int i; + + params->size_of_opaque_state = sizeof(*state); + params->mmap_prot = PROT_READ | PROT_WRITE; + params->mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS; + for (i = 0; i < ARRAY_SIZE(params->reserved); i++) + params->reserved[i] = 0; + return 0; }
--
2.44.0