From: Borislav Petkov bp@suse.de
[ Upstream commit f96b4675839b66168f5a07bf964dde6c2f1c4885 ]
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 sfr@canb.auug.org.au
No functional changes.
Fixes: 5ba1071f7554 ("x86/insn, tools/x86: Fix undefined behavior due to potential unaligned accesses") Suggested-by: Linus Torvalds torvalds@linux-foundation.org Signed-off-by: Borislav Petkov bp@suse.de Acked-by: Masami Hiramatsu mhiramat@kernel.org Tested-by: Stephen Rothwell sfr@canb.auug.org.au Link: https://lkml.kernel.org/r/YVSsIkj9Z29TyUjE@zn.tnic Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/lib/insn.c | 5 +++-- tools/arch/x86/lib/insn.c | 5 +++-- tools/include/asm-generic/unaligned.h | 23 +++++++++++++++++++++++ tools/perf/util/intel-pt-decoder/Build | 2 ++ 4 files changed, 31 insertions(+), 4 deletions(-) create mode 100644 tools/include/asm-generic/unaligned.h
diff --git a/arch/x86/lib/insn.c b/arch/x86/lib/insn.c index c565def611e24..55e371cc69fd5 100644 --- a/arch/x86/lib/insn.c +++ b/arch/x86/lib/insn.c @@ -13,6 +13,7 @@ #endif #include <asm/inat.h> /*__ignore_sync_check__ */ #include <asm/insn.h> /* __ignore_sync_check__ */ +#include <asm/unaligned.h> /* __ignore_sync_check__ */
#include <linux/errno.h> #include <linux/kconfig.h> @@ -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); }) diff --git a/tools/arch/x86/lib/insn.c b/tools/arch/x86/lib/insn.c index 797699462cd8e..8fd63a067308a 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 <linux/errno.h> #include <linux/kconfig.h> @@ -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); }) diff --git a/tools/include/asm-generic/unaligned.h b/tools/include/asm-generic/unaligned.h new file mode 100644 index 0000000000000..47387c607035e --- /dev/null +++ b/tools/include/asm-generic/unaligned.h @@ -0,0 +1,23 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * Copied from the kernel sources to tools/perf/: + */ + +#ifndef __TOOLS_LINUX_ASM_GENERIC_UNALIGNED_H +#define __TOOLS_LINUX_ASM_GENERIC_UNALIGNED_H + +#define __get_unaligned_t(type, ptr) ({ \ + const struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr); \ + __pptr->x; \ +}) + +#define __put_unaligned_t(type, val, ptr) do { \ + struct { type x; } __packed *__pptr = (typeof(__pptr))(ptr); \ + __pptr->x = (val); \ +} while (0) + +#define get_unaligned(ptr) __get_unaligned_t(typeof(*(ptr)), (ptr)) +#define put_unaligned(val, ptr) __put_unaligned_t(typeof(*(ptr)), (val), (ptr)) + +#endif /* __TOOLS_LINUX_ASM_GENERIC_UNALIGNED_H */ + diff --git a/tools/perf/util/intel-pt-decoder/Build b/tools/perf/util/intel-pt-decoder/Build index bc629359826fb..b41c2e9c6f887 100644 --- a/tools/perf/util/intel-pt-decoder/Build +++ b/tools/perf/util/intel-pt-decoder/Build @@ -18,3 +18,5 @@ CFLAGS_intel-pt-insn-decoder.o += -I$(OUTPUT)util/intel-pt-decoder ifeq ($(CC_NO_CLANG), 1) CFLAGS_intel-pt-insn-decoder.o += -Wno-override-init endif + +CFLAGS_intel-pt-insn-decoder.o += -Wno-packed