The following commit has been merged into the x86/misc branch of tip:
Commit-ID: a1be25a30cf654b3314bc7b26db5e52716833144
Gitweb: https://git.kernel.org/tip/a1be25a30cf654b3314bc7b26db5e52716833144
Author: Borislav Petkov <bp@xxxxxxx>
AuthorDate: Wed, 29 Sep 2021 16:37:53 +02:00
Committer: Borislav Petkov <bp@xxxxxxx>
CommitterDate: Mon, 04 Oct 2021 11:11:58 +02:00
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.
No functional changes.
Fixes: 5ba1071f7554 ("x86/insn, tools/x86: Fix undefined behavior due to potential unaligned accesses")
Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Borislav Petkov <bp@xxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Link: https://lkml.kernel.org/r/YVSsIkj9Z29TyUjE@xxxxxxx
---
arch/x86/lib/insn.c | 5 +++--
tools/arch/x86/lib/insn.c | 5 +++--
tools/include/asm-generic/unaligned.h | 23 +++++++++++++++++++++++
3 files changed, 29 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 c565def..55e371c 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 7976994..8fd63a0 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 0000000..47387c6
--- /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 */
+
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