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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id l12sm2811933pff.105.2021.06.16.13.18.25 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 16 Jun 2021 13:18:25 -0700 (PDT) From: Kees Cook To: Heiko Carstens Cc: Kees Cook , Vasily Gorbik , Christian Borntraeger , Sven Schnelle , linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] s390/speculation: Use statically initialized const for instructions Date: Wed, 16 Jun 2021 13:18:23 -0700 Message-Id: <20210616201823.1245603-1-keescook@chromium.org> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Patch-Hashes: v=1; h=sha256; g=a7efa10bf74410da3d723823c01a21cb7719ac72; i=0EJdiCO/sZbZCBfXSQAnM+hJ3BSDIu+0E7SNvnsr1Uw=; m=5FhAIifPI+dYPrslVAUOeGdnxZTyWY2lqLeWsSo/HBg=; p=pzb0+IfaYNnb577lCHX4XoK00ch1a0s2NZRs99V638o= X-Patch-Sig: m=pgp; i=keescook@chromium.org; s=0x0x8972F4DFDC6DC026; b=iQIzBAABCgAdFiEEpcP2jyKd1g9yPm4TiXL039xtwCYFAmDKXI4ACgkQiXL039xtwCbagBAAjg+ 2FPDcEj+98as41P97H8JzfPrDikMwwmT9fIza8v1hc5o/MoU7LMRBDYfN7hxPAecO1FI+g81xscyE 0+4M+nfN11I78iH/RVuXJPG01xutEahxwzplV2phTKv/EipRvUwtD32BALG6c/p9IZpluCFuw8t4U iaF1bGdBwFlRgvUM0OhKgLbQ4Qa7jDdPJbj2N2X8gQiCDm6HWn7vIVtHRZmE6QZRl36KD+DmPxlJD GtxKQMfQ5Crk34O1Dneyk8xNYwxLAzllBtFHf2fM7Bz3QahNqYVwq0MtQRZaPJHGpi152wnArP4Ab jko4+W3/y0FmzFDyQCRMPocr0opF5vAc75zzpw1N/wAOrN6qKaiuBCeUzy4wGWAiXZy9cyuqbfRkC 6Lra/zcvwchjeGkDkb+Ljr4mFqxPQuvi3vpZy0YRtrZG0GmKpLcfP/Kzc1/e9letFMIZ8FsGGoZit lh04A5WbfQGcRCxcEAO/tyF6M3qpAS4A8UF1Sak6XHMSU03FmHLUChgcBR4qNO17tehsGkFKa2RUl enuHuUUz9VethESRmN9Zi+grMhDPQ6efbk2VTDgIUBQvT+mnPjIg6kGn1qQrGeLsBgJx09yAs1Asx +k6L4NCoVoo0hRyn1jpCr/IdVMImeHDj3TRzxUW5G1NjVDaGXfIXb4m9d/OsNGGA= Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org 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 --- 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 2c5c3756644b..250e4dbf653c 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]; -- 2.25.1