[PATCH] D104155: Add documentation for -fsanitize-address-use-after-return.

[Kevin Athey via Phabricator via cfe-commits]

kda updated this revision to Diff 357385.
kda marked an inline comment as done.
kda added a comment.

- removed redundant mention of the flag.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D104155/new/

https://reviews.llvm.org/D104155

Files:
  clang/docs/AddressSanitizer.rst
  clang/docs/UsersManual.rst
  clang/include/clang/Driver/Options.td


Index: clang/include/clang/Driver/Options.td
===================================================================
--- clang/include/clang/Driver/Options.td
+++ clang/include/clang/Driver/Options.td
@@ -1584,7 +1584,7 @@
   : Joined<["-"], "fsanitize-address-use-after-return=">,
     MetaVarName<"<mode>">,
     Flags<[CC1Option]>,
-    HelpText<"Select the mode of detecting stack use-after-return in AddressSanitizer">,
+    HelpText<"Select the mode of detecting stack use-after-return in AddressSanitizer: never | runtime (default) | always">,
     Group<f_clang_Group>,
     Values<"never,runtime,always">,
     NormalizedValuesScope<"llvm::AsanDetectStackUseAfterReturnMode">,
Index: clang/docs/UsersManual.rst
===================================================================
--- clang/docs/UsersManual.rst
+++ clang/docs/UsersManual.rst
@@ -3744,6 +3744,8 @@
                               Enable linker dead stripping of globals in AddressSanitizer
       -fsanitize-address-poison-custom-array-cookie
                               Enable poisoning array cookies when using custom operator new[] in AddressSanitizer
+      -fsanitize-address-use-after-return=<mode>
+                              Select the mode of detecting stack use-after-return in AddressSanitizer: never | runtime (default) | always
       -fsanitize-address-use-after-scope
                               Enable use-after-scope detection in AddressSanitizer
       -fsanitize-address-use-odr-indicator
Index: clang/docs/AddressSanitizer.rst
===================================================================
--- clang/docs/AddressSanitizer.rst
+++ clang/docs/AddressSanitizer.rst
@@ -14,8 +14,9 @@
 
 * Out-of-bounds accesses to heap, stack and globals
 * Use-after-free
-* Use-after-return (runtime flag `ASAN_OPTIONS=detect_stack_use_after_return=1`)
-* Use-after-scope (clang flag `-fsanitize-address-use-after-scope`)
+* Use-after-return (clang flag ``-fsanitize-address-use-after-return=(never|runtime|always)`` default: ``runtime``)
+    * Enable ``runtime`` with: ``ASAN_OPTIONS=detect_stack_use_after_return=1``
+* Use-after-scope (clang flag ``-fsanitize-address-use-after-scope``)
 * Double-free, invalid free
 * Memory leaks (experimental)
 
@@ -136,6 +137,26 @@
 
 Note that this option is not supported on macOS.
 
+Stack Use After Return (UAR)
+----------------------------
+
+AddressSanitizer can optionally detect stack use after return problems.
+This is available by default, or explicitly
+(``-fsanitize-address-use-after-return=runtime``).
+To enable this check at runtime, set the environment variable
+``ASAN_OPTIONS=detect_stack_use_after_return=1``.
+
+Enabling this check (``-fsanitize-address-use-after-return=always``) will
+reduce code size.  The code size may be reduced further by completely
+eliminating this check (``-fsanitize-address-use-after-return=never``).
+
+To summarize: ``-fsanitize-address-use-after-return=<mode>``
+  * ``never``: Completely disables detection of UAR errors (reduces code size).
+  * ``runtime``: Adds the code for detection, but must be enabled via the
+    runtime environment (``ASAN_OPTIONS=detect_stack_use_after_return=1``).
+  * ``always``: Enables detection of UAR errors in all cases. (reduces code
+    size, but not as much as ``never``).
+
 Memory leak detection
 ---------------------
 


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