From: Sami Tolvanen <samitolvanen@google.com>
To: Paul Walmsley <paul.walmsley@sifive.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Albert Ou <aou@eecs.berkeley.edu>,
Kees Cook <keescook@chromium.org>
Cc: Clement Leger <cleger@rivosinc.com>, Guo Ren <guoren@kernel.org>,
Deepak Gupta <debug@rivosinc.com>,
Nathan Chancellor <nathan@kernel.org>,
Nick Desaulniers <ndesaulniers@google.com>,
Fangrui Song <maskray@google.com>,
linux-riscv@lists.infradead.org, llvm@lists.linux.dev,
linux-kernel@vger.kernel.org,
Sami Tolvanen <samitolvanen@google.com>
Subject: [PATCH v3 6/6] lkdtm: Fix CFI_BACKWARD on RISC-V
Date: Mon, 28 Aug 2023 19:58:40 +0000 [thread overview]
Message-ID: <20230828195833.756747-14-samitolvanen@google.com> (raw)
In-Reply-To: <20230828195833.756747-8-samitolvanen@google.com>
On RISC-V, the return address is before the current frame pointer,
unlike on most other architectures. Use the correct offset on RISC-V
to fix the CFI_BACKWARD test.
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
---
drivers/misc/lkdtm/cfi.c | 13 +++++++++++--
1 file changed, 11 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c
index fc28714ae3a6..6a33889d0902 100644
--- a/drivers/misc/lkdtm/cfi.c
+++ b/drivers/misc/lkdtm/cfi.c
@@ -68,12 +68,20 @@ static void lkdtm_CFI_FORWARD_PROTO(void)
#define no_pac_addr(addr) \
((__force __typeof__(addr))((uintptr_t)(addr) | PAGE_OFFSET))
+#ifdef CONFIG_RISCV
+/* https://github.com/riscv-non-isa/riscv-elf-psabi-doc/blob/master/riscv-cc.adoc#frame-pointer-convention */
+#define FRAME_RA_OFFSET (-1)
+#else
+#define FRAME_RA_OFFSET 1
+#endif
+
/* The ultimate ROP gadget. */
static noinline __no_ret_protection
void set_return_addr_unchecked(unsigned long *expected, unsigned long *addr)
{
/* Use of volatile is to make sure final write isn't seen as a dead store. */
- unsigned long * volatile *ret_addr = (unsigned long **)__builtin_frame_address(0) + 1;
+ unsigned long * volatile *ret_addr =
+ (unsigned long **)__builtin_frame_address(0) + FRAME_RA_OFFSET;
/* Make sure we've found the right place on the stack before writing it. */
if (no_pac_addr(*ret_addr) == expected)
@@ -88,7 +96,8 @@ static noinline
void set_return_addr(unsigned long *expected, unsigned long *addr)
{
/* Use of volatile is to make sure final write isn't seen as a dead store. */
- unsigned long * volatile *ret_addr = (unsigned long **)__builtin_frame_address(0) + 1;
+ unsigned long * volatile *ret_addr =
+ (unsigned long **)__builtin_frame_address(0) + FRAME_RA_OFFSET;
/* Make sure we've found the right place on the stack before writing it. */
if (no_pac_addr(*ret_addr) == expected)
--
2.42.0.rc2.253.gd59a3bf2b4-goog
_______________________________________________
linux-riscv mailing list
linux-riscv@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-riscv
prev parent reply other threads:[~2023-08-28 19:59 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-28 19:58 [PATCH v3 0/6] riscv: SCS support Sami Tolvanen
2023-08-28 19:58 ` [PATCH v3 1/6] riscv: VMAP_STACK overflow detection thread-safe Sami Tolvanen
2023-08-28 19:58 ` [PATCH v3 2/6] riscv: Deduplicate IRQ stack switching Sami Tolvanen
2023-08-29 3:35 ` Guo Ren
2023-08-28 19:58 ` [PATCH v3 3/6] riscv: Move global pointer loading to a macro Sami Tolvanen
2023-08-28 19:58 ` [PATCH v3 4/6] riscv: Implement Shadow Call Stack Sami Tolvanen
2023-08-28 19:58 ` [PATCH v3 5/6] riscv: Use separate IRQ shadow call stacks Sami Tolvanen
2023-08-28 19:58 ` Sami Tolvanen [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230828195833.756747-14-samitolvanen@google.com \
--to=samitolvanen@google.com \
--cc=aou@eecs.berkeley.edu \
--cc=cleger@rivosinc.com \
--cc=debug@rivosinc.com \
--cc=guoren@kernel.org \
--cc=keescook@chromium.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=llvm@lists.linux.dev \
--cc=maskray@google.com \
--cc=nathan@kernel.org \
--cc=ndesaulniers@google.com \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).