[libc-commits] [libc] [libc] fortify jmp buffer for x86-64 (PR #112769)

[Schrodinger ZHU Yifan via libc-commits]

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@@ -8,35 +8,83 @@
 
 #include "src/setjmp/longjmp.h"
 #include "include/llvm-libc-macros/offsetof-macro.h"
+#include "src/__support/OSUtil/io.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/setjmp/checksum.h"
+#include "src/stdlib/abort.h"
 
 #if !defined(LIBC_TARGET_ARCH_IS_X86_64)
 #error "Invalid file include"
 #endif
 
 namespace LIBC_NAMESPACE_DECL {
 
+#if LIBC_COPT_SETJMP_ENABLE_FORTIFICATION
+extern "C" [[gnu::cold, noreturn]] void __libc_jmpbuf_corruption() {
+  write_to_stderr("invalid checksum detected in longjmp\n");
+  abort();
+}
+#define LOAD_CHKSUM_STATE_REGISTERS()                                          \
+  asm("mov %0, %%rcx\n\t" ::"m"(jmpbuf::value_mask) : "rcx");                  \
+  asm("mov %0, %%rdx\n\t" ::"m"(jmpbuf::checksum_cookie) : "rdx");
+
+#define RESTORE_REG(DST)                                                       \
+  "movq %c[" #DST "](%%rdi), %%rax\n\t"                                        \
+  "movq %%rax, %%" #DST "\n\t"                                                 \
+  "xor %%rcx, %%" #DST "\n\t"                                                  \
+  "mul %%rdx\n\t"                                                              \
+  "xor %%rax, %%rdx\n\t"                                                       \
+  "rol $%c[rotation], %%rdx\n\t"
----------------
SchrodingerZhu wrote:

See also https://github.com/tkaitchuck/aHash/blob/7d5c661a74b12d5bc5448b0b83fdb429190db1a3/src/fallback_hash.rs#L65C1-L93C84

https://github.com/llvm/llvm-project/pull/112769