kcc added a comment.
[didn't look at the code yet, just at the docs]
Please add a docs section describing how to handle leaf functions.
If they are not handled yet, no need to change the implementation in these
pathches -- ok to do it later.
================
Comment at: docs/ShadowCallStack.rst:14
+buffer overflows. It works by saving a function's return address to a
+separately allocated 'shadow call stack' in the function prolog and checking
the
+return address on the stack against the shadow call stack in the function
----------------
prologue/epilogue?
(it's your native tongue, not mine, though)
================
Comment at: docs/ShadowCallStack.rst:20
+and trade-off consuming more memory for shorter function prologs and epilogs
+with fewer memory accesses.
+
----------------
Provide short comparison with RFG (more instructions, less memory, same racy
attack)
================
Comment at: docs/ShadowCallStack.rst:38
+return address and bypass ShadowCallStack. Similarly, there is a time-of-check-
+to-time-of-use race in the function prolog where an attacker could overwrite
the
+return address after it has been checked and before it has been returned to.
----------------
link to wikipedia maybe?
================
Comment at: docs/ShadowCallStack.rst:41
+Modifying the call-return semantics to fix this on x86_64 would incur an
+unacceptable performance overhead.
+
----------------
... due to return branch predictor (or some such)
================
Comment at: docs/ShadowCallStack.rst:47
+not easily leak its address.
+
+Usage
----------------
Say something about attacks that first try to discover the secret location of
the shadow call stack.
side channels, thread spaying, whatever you have.
================
Comment at: docs/ShadowCallStack.rst:74
+declaration to specify that the shadow call stack instrumentation should not be
+applied to that function, even if enabled globally.
----------------
Please add a section that shows the assembly for the following example:
int foo() {
return bar() + 1;
}
Repository:
rC Clang
https://reviews.llvm.org/D44801
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