While the run-time testing of FORTIFY_SOURCE is already present in LKDTM, there is no testing of the expected compile-time detections. In preparation for correctly supporting FORTIFY_SOURCE under Clang, adding additional FORTIFY_SOURCE defenses, and making sure FORTIFY_SOURCE doesn't silently regress with GCC, introduce a build-time test suite that checks each expected compile-time failure condition. As this is relatively backwards from standard build rules in the sense that a successful test is actually a compile _failure_, create a wrapper script to check for the correct errors, and wire it up as a dummy dependency to lib/string.o, collecting the results into a log file artifact.
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| 1 | #!/bin/sh | ||
| 2 | # SPDX-License-Identifier: GPL-2.0-only | ||
| 3 | set -e | ||
| 4 | |||
| 5 | # Argument 1: Source file to build. | ||
| 6 | IN="$1" | ||
| 7 | shift | ||
| 8 | # Extract just the filename for error messages below. | ||
| 9 | FILE="${IN##*/}" | ||
| 10 | # Extract the function name for error messages below. | ||
| 11 | FUNC="${FILE#*-}" | ||
| 12 | FUNC="${FUNC%%-*}" | ||
| 13 | FUNC="${FUNC%%.*}" | ||
| 14 | # Extract the symbol to test for in build/symbol test below. | ||
| 15 | WANT="__${FILE%%-*}" | ||
| 16 | |||
| 17 | # Argument 2: Where to write the build log. | ||
| 18 | OUT="$1" | ||
| 19 | shift | ||
| 20 | TMP="${OUT}.tmp" | ||
| 21 | |||
| 22 | # Argument 3: Path to "nm" tool. | ||
| 23 | NM="$1" | ||
| 24 | shift | ||
| 25 | |||
| 26 | # Remaining arguments are: $(CC) $(c_flags) | ||
| 27 | |||
| 28 | # Clean up temporary file at exit. | ||
| 29 | __cleanup() { | ||
| 30 | rm -f "$TMP" | ||
| 31 | } | ||
| 32 | trap __cleanup EXIT | ||
| 33 | |||
| 34 | # Function names in warnings are wrapped in backticks under UTF-8 locales. | ||
| 35 | # Run the commands with LANG=C so that grep output will not change. | ||
| 36 | export LANG=C | ||
| 37 | |||
| 38 | status= | ||
| 39 | # Attempt to build a source that is expected to fail with a specific warning. | ||
| 40 | if "$@" -Werror -c "$IN" -o "$OUT".o 2> "$TMP" ; then | ||
| 41 | # If the build succeeds, either the test has failed or the | ||
| 42 | # warning may only happen at link time (Clang). In that case, | ||
| 43 | # make sure the expected symbol is unresolved in the symbol list. | ||
| 44 | # If so, FORTIFY is working for this case. | ||
| 45 | if ! $NM -A "$OUT".o | grep -m1 "\bU ${WANT}$" >>"$TMP" ; then | ||
| 46 | status="warning: unsafe ${FUNC}() usage lacked '$WANT' symbol in $IN" | ||
| 47 | fi | ||
| 48 | else | ||
| 49 | # If the build failed, check for the warning in the stderr (gcc). | ||
| 50 | if ! grep -q -m1 "error: call to .\b${WANT}\b." "$TMP" ; then | ||
| 51 | status="warning: unsafe ${FUNC}() usage lacked '$WANT' warning in $IN" | ||
| 52 | fi | ||
| 53 | fi | ||
| 54 | |||
| 55 | if [ -n "$status" ]; then | ||
| 56 | # Report on failure results, including compilation warnings. | ||
| 57 | echo "$status" | tee "$OUT" >&2 | ||
| 58 | else | ||
| 59 | # Report on good results, and save any compilation output to log. | ||
| 60 | echo "ok: unsafe ${FUNC}() usage correctly detected with '$WANT' in $IN" >"$OUT" | ||
| 61 | fi | ||
| 62 | cat "$TMP" >>"$OUT" | ||