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Ard Biesheuvel
b272ed230e
The "ground truth" stack protector cookie value is kept in a global variable, and loaded in every function prologue and epilogue to store it into resp. compare it with the stack slot holding the cookie. If the comparison fails, the program aborts, and this might occur spuriously when the global variable changes values between the entry and exit of a function. This implies that assigning the global variable at boot should not involve any instrumented function calls, unless special care is taken to ensure that the live call stack is synchronized, which is non-trivial. So avoid any function calls, including grub_memcpy(), which is unnecessary given that the stack cookie is always a suitably aligned variable of the native word size. While at it, leave the last byte 0x0 to avoid inadvertent unbounded strings on the stack. Note that the use of __attribute__((optimize)) is described as unsuitable for production use in the GCC documentation, so let's drop this as well now that it is no longer needed. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Signed-off-by: Glenn Washburn <development@efficientek.com> Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>