Thread (19 messages) 19 messages, 2 authors, 2021-03-31
STALE1890d REVIEWED: 1 (0M)
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[PATCH v4 15/17] arm64: add __nocfi to __apply_alternatives

From: Sami Tolvanen <samitolvanen@google.com>
Date: 2021-03-31 21:29:25
Also in: bpf, linux-arch, linux-hardening, linux-kbuild, linux-pci, lkml
Subsystem: arm64 port (aarch64 architecture), the rest · Maintainers: Catalin Marinas, Will Deacon, Linus Torvalds

__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 <redacted>
---
 arch/arm64/kernel/alternative.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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;
-- 
2.31.0.291.g576ba9dcdaf-goog


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