From: Numfor Mbiziwo-Tiapo nums@google.com
[ Upstream commit 5ba1071f7554c4027bdbd712a146111de57918de ]
Don't perform unaligned loads in __get_next() and __peek_nbyte_next() as these are forms of undefined behavior:
"A pointer to an object or incomplete type may be converted to a pointer to a different object or incomplete type. If the resulting pointer is not correctly aligned for the pointed-to type, the behavior is undefined."
(from http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1256.pdf)
These problems were identified using the undefined behavior sanitizer (ubsan) with the tools version of the code and perf test.
[ bp: Massage commit message. ]
Signed-off-by: Numfor Mbiziwo-Tiapo nums@google.com Signed-off-by: Ian Rogers irogers@google.com Signed-off-by: Borislav Petkov bp@suse.de Acked-by: Masami Hiramatsu mhiramat@kernel.org Link: https://lkml.kernel.org/r/20210923161843.751834-1-irogers@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/lib/insn.c | 4 ++-- tools/arch/x86/lib/insn.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-)
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c index 058f19b20465..c565def611e2 100644 --- a/arch/x86/lib/insn.c +++ b/arch/x86/lib/insn.c @@ -37,10 +37,10 @@ ((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
#define __get_next(t, insn) \ - ({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); leXX_to_cpu(t, r); }) + ({ t r; memcpy(&r, insn->next_byte, sizeof(t)); insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
#define __peek_nbyte_next(t, insn, n) \ - ({ t r = *(t*)((insn)->next_byte + n); leXX_to_cpu(t, r); }) + ({ t r; memcpy(&r, (insn)->next_byte + n, sizeof(t)); leXX_to_cpu(t, r); })
#define get_next(t, insn) \ ({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); }) diff --git a/tools/arch/x86/lib/insn.c b/tools/arch/x86/lib/insn.c index c41f95815480..797699462cd8 100644 --- a/tools/arch/x86/lib/insn.c +++ b/tools/arch/x86/lib/insn.c @@ -37,10 +37,10 @@ ((insn)->next_byte + sizeof(t) + n <= (insn)->end_kaddr)
#define __get_next(t, insn) \ - ({ t r = *(t*)insn->next_byte; insn->next_byte += sizeof(t); leXX_to_cpu(t, r); }) + ({ t r; memcpy(&r, insn->next_byte, sizeof(t)); insn->next_byte += sizeof(t); leXX_to_cpu(t, r); })
#define __peek_nbyte_next(t, insn, n) \ - ({ t r = *(t*)((insn)->next_byte + n); leXX_to_cpu(t, r); }) + ({ t r; memcpy(&r, (insn)->next_byte + n, sizeof(t)); leXX_to_cpu(t, r); })
#define get_next(t, insn) \ ({ if (unlikely(!validate_next(t, insn, 0))) goto err_out; __get_next(t, insn); })