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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 <keescook@chromium.org>
Link: https://lore.kernel.org/r/20210616201823.1245603-1-keescook@chromium.org
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
This commit is contained in:
Kees Cook 2021-06-16 13:18:23 -07:00 committed by Vasily Gorbik
parent e5e1bdf0bc
commit c74d3c182a
1 changed files with 2 additions and 1 deletions
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3
arch/s390/kernel/nospec-branch.c
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@ -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];