diff mbox series

[15/17] arm64: add __nocfi to __apply_alternatives

Message ID 20210312004919.669614-16-samitolvanen@google.com (mailing list archive)
State New
Headers show
Series Add support for Clang CFI | expand

Commit Message

Sami Tolvanen March 12, 2021, 12:49 a.m. UTC
__apply_alternatives makes indirect calls to functions whose address
is taken in assembly code using the alternative_cb macro. With
non-canonical CFI, the compiler won't replace these function
references with the jump table addresses, which trips CFI. Disable CFI
checking in the function to work around the issue.

Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 arch/arm64/kernel/alternative.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Comments

Kees Cook March 12, 2021, 2:50 a.m. UTC | #1
On Thu, Mar 11, 2021 at 04:49:17PM -0800, Sami Tolvanen wrote:
> __apply_alternatives makes indirect calls to functions whose address
> is taken in assembly code using the alternative_cb macro. With
> non-canonical CFI, the compiler won't replace these function
> references with the jump table addresses, which trips CFI. Disable CFI
> checking in the function to work around the issue.
> 
> Signed-off-by: Sami Tolvanen <samitolvanen@google.com>

Reviewed-by: Kees Cook <keescook@chromium.org>
diff mbox series

Patch

diff --git a/arch/arm64/kernel/alternative.c b/arch/arm64/kernel/alternative.c
index 1184c44ea2c7..abc84636af07 100644
--- a/arch/arm64/kernel/alternative.c
+++ b/arch/arm64/kernel/alternative.c
@@ -133,8 +133,8 @@  static void clean_dcache_range_nopatch(u64 start, u64 end)
 	} while (cur += d_size, cur < end);
 }
 
-static void __apply_alternatives(void *alt_region,  bool is_module,
-				 unsigned long *feature_mask)
+static void __nocfi __apply_alternatives(void *alt_region,  bool is_module,
+					 unsigned long *feature_mask)
 {
 	struct alt_instr *alt;
 	struct alt_region *region = alt_region;