From f96b4675839b66168f5a07bf964dde6c2f1c4885 Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Wed, 29 Sep 2021 16:37:53 +0200 Subject: x86/insn: Use get_unaligned() instead of memcpy() Use get_unaligned() instead of memcpy() to access potentially unaligned memory, which, when accessed through a pointer, leads to undefined behavior. get_unaligned() describes much better what is happening there anyway even if memcpy() does the job. In addition, since perf tool builds with -Werror, it would fire with: util/intel-pt-decoder/../../../arch/x86/lib/insn.c: In function '__insn_get_emulate_prefix': tools/include/../include/asm-generic/unaligned.h:10:15: error: packed attribute is unnecessary [-Werror=packed] 10 | const struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr); \ because -Werror=packed would complain if the packed attribute would have no effect on the layout of the structure. In this case, that is intentional so disable the warning only for that compilation unit. That part is Reported-by: Stephen Rothwell No functional changes. Fixes: 5ba1071f7554 ("x86/insn, tools/x86: Fix undefined behavior due to potential unaligned accesses") Suggested-by: Linus Torvalds Signed-off-by: Borislav Petkov Acked-by: Masami Hiramatsu Tested-by: Stephen Rothwell Link: https://lkml.kernel.org/r/YVSsIkj9Z29TyUjE@zn.tnic --- tools/arch/x86/lib/insn.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) (limited to 'tools/arch') diff --git a/tools/arch/x86/lib/insn.c b/tools/arch/x86/lib/insn.c index 797699462cd8..8fd63a067308 100644 --- a/tools/arch/x86/lib/insn.c +++ b/tools/arch/x86/lib/insn.c @@ -13,6 +13,7 @@ #endif #include "../include/asm/inat.h" /* __ignore_sync_check__ */ #include "../include/asm/insn.h" /* __ignore_sync_check__ */ +#include "../include/asm-generic/unaligned.h" /* __ignore_sync_check__ */ #include #include @@ -37,10 +38,10 @@ ((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr) #define __get_next(t, insn) \ - ({ t r; memcpy(&r, insn->next_byte, sizeof(t)); insn->next_byte += sizeof(t); leXX_to_cpu(t, r); }) + ({ t r = get_unaligned((t *)(insn)->next_byte); (insn)->next_byte += sizeof(t); leXX_to_cpu(t, r); }) #define __peek_nbyte_next(t, insn, n) \ - ({ t r; memcpy(&r, (insn)->next_byte + n, sizeof(t)); leXX_to_cpu(t, r); }) + ({ t r = get_unaligned((t *)(insn)->next_byte + n); leXX_to_cpu(t, r); }) #define get_next(t, insn) \ ({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); }) -- cgit