From c74d3c182ab4a3db6c3c2a6c4b3c8b9a7f1feb1a Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Wed, 16 Jun 2021 13:18:23 -0700 Subject: [PATCH] s390/speculation: Use statically initialized const for instructions In preparation for FORTIFY_SOURCE performing compile-time and run-time field bounds checking for memcpy(), memmove(), and memset(), avoid confusing the checks when using a static const source. Move the static const array into a variable so the compiler can perform appropriate bounds checking. Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20210616201823.1245603-1-keescook@chromium.org Signed-off-by: Vasily Gorbik --- arch/s390/kernel/nospec-branch.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/s390/kernel/nospec-branch.c b/arch/s390/kernel/nospec-branch.c index 2c5c3756644b4..250e4dbf653cc 100644 --- a/arch/s390/kernel/nospec-branch.c +++ b/arch/s390/kernel/nospec-branch.c @@ -99,6 +99,7 @@ early_param("spectre_v2", spectre_v2_setup_early); static void __init_or_module __nospec_revert(s32 *start, s32 *end) { enum { BRCL_EXPOLINE, BRASL_EXPOLINE } type; + static const u8 branch[] = { 0x47, 0x00, 0x07, 0x00 }; u8 *instr, *thunk, *br; u8 insnbuf[6]; s32 *epo; @@ -128,7 +129,7 @@ static void __init_or_module __nospec_revert(s32 *start, s32 *end) if ((br[0] & 0xbf) != 0x07 || (br[1] & 0xf0) != 0xf0) continue; - memcpy(insnbuf + 2, (char[]) { 0x47, 0x00, 0x07, 0x00 }, 4); + memcpy(insnbuf + 2, branch, sizeof(branch)); switch (type) { case BRCL_EXPOLINE: insnbuf[0] = br[0]; -- 2.30.2