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Message-ID: <163248031804.25758.7658032205520387028.tip-bot2@tip-bot2>
Date: Fri, 24 Sep 2021 10:45:18 -0000
From: "tip-bot2 for Numfor Mbiziwo-Tiapo" <tip-bot2@...utronix.de>
To: linux-tip-commits@...r.kernel.org
Cc: "Numfor Mbiziwo-Tiapo" <nums@...gle.com>,
Ian Rogers <irogers@...gle.com>, Borislav Petkov <bp@...e.de>,
Masami Hiramatsu <mhiramat@...nel.org>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: [tip: x86/urgent] x86/insn, tools/x86: Fix undefined behavior due to
potential unaligned accesses
The following commit has been merged into the x86/urgent branch of tip:
Commit-ID: 5ba1071f7554c4027bdbd712a146111de57918de
Gitweb: https://git.kernel.org/tip/5ba1071f7554c4027bdbd712a146111de57918de
Author: Numfor Mbiziwo-Tiapo <nums@...gle.com>
AuthorDate: Thu, 23 Sep 2021 09:18:43 -07:00
Committer: Borislav Petkov <bp@...e.de>
CommitterDate: Fri, 24 Sep 2021 12:37:38 +02:00
x86/insn, tools/x86: Fix undefined behavior due to potential unaligned accesses
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@...gle.com>
Signed-off-by: Ian Rogers <irogers@...gle.com>
Signed-off-by: Borislav Petkov <bp@...e.de>
Acked-by: Masami Hiramatsu <mhiramat@...nel.org>
Link: https://lkml.kernel.org/r/20210923161843.751834-1-irogers@google.com
---
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 058f19b..c565def 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 c41f958..7976994 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); })
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