diff options
| author | Sami Tolvanen <samitolvanen@google.com> | 2023-09-27 22:48:04 +0000 |
|---|---|---|
| committer | Palmer Dabbelt <palmer@rivosinc.com> | 2023-10-27 14:43:10 -0700 |
| commit | 245561ba6d5de42bf73d501f910b181bc7fa5601 (patch) | |
| tree | cdb1e0ca68e70b2ba8e0f0258adfdedf28733a9b /drivers/misc/lkdtm | |
| parent | c40fef858d002fb027033c572ac8bdf8756a2c6b (diff) | |
| download | linux-245561ba6d5de42bf73d501f910b181bc7fa5601.tar.gz | |
lkdtm: Fix CFI_BACKWARD on RISC-V
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>
Link: https://lore.kernel.org/r/20230927224757.1154247-14-samitolvanen@google.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
Diffstat (limited to 'drivers/misc/lkdtm')
| -rw-r--r-- | drivers/misc/lkdtm/cfi.c | 13 |
1 files changed, 11 insertions, 2 deletions
diff --git a/drivers/misc/lkdtm/cfi.c b/drivers/misc/lkdtm/cfi.c index fc28714ae3a61..6a33889d0902a 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) |