| From 04831e892b41618914b2123ae3b4fa77252e8656 Mon Sep 17 00:00:00 2001 |
| From: Kees Cook <keescook@chromium.org> |
| Date: Wed, 23 Jun 2021 13:39:28 -0700 |
| Subject: selftests/lkdtm: Avoid needing explicit sub-shell |
| |
| From: Kees Cook <keescook@chromium.org> |
| |
| commit 04831e892b41618914b2123ae3b4fa77252e8656 upstream. |
| |
| Some environments do not set $SHELL when running tests. There's no |
| need to use $SHELL here anyway, since "cat" can be used to receive any |
| delivered signals from the kernel. Additionally avoid using bash-isms |
| in the command, and record stderr for posterity. |
| |
| Fixes: 46d1a0f03d66 ("selftests/lkdtm: Add tests for LKDTM targets") |
| Cc: stable@vger.kernel.org |
| Suggested-by: Guillaume Tucker <guillaume.tucker@collabora.com> |
| Suggested-by: David Laight <David.Laight@ACULAB.COM> |
| Signed-off-by: Kees Cook <keescook@chromium.org> |
| Link: https://lore.kernel.org/r/20210623203936.3151093-2-keescook@chromium.org |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| |
| --- |
| tools/testing/selftests/lkdtm/run.sh | 12 ++++++++---- |
| 1 file changed, 8 insertions(+), 4 deletions(-) |
| |
| --- a/tools/testing/selftests/lkdtm/run.sh |
| +++ b/tools/testing/selftests/lkdtm/run.sh |
| @@ -76,10 +76,14 @@ fi |
| # Save existing dmesg so we can detect new content below |
| dmesg > "$DMESG" |
| |
| -# Most shells yell about signals and we're expecting the "cat" process |
| -# to usually be killed by the kernel. So we have to run it in a sub-shell |
| -# and silence errors. |
| -($SHELL -c 'cat <(echo '"$test"') >'"$TRIGGER" 2>/dev/null) || true |
| +# Since the kernel is likely killing the process writing to the trigger |
| +# file, it must not be the script's shell itself. i.e. we cannot do: |
| +# echo "$test" >"$TRIGGER" |
| +# Instead, use "cat" to take the signal. Since the shell will yell about |
| +# the signal that killed the subprocess, we must ignore the failure and |
| +# continue. However we don't silence stderr since there might be other |
| +# useful details reported there in the case of other unexpected conditions. |
| +echo "$test" | cat >"$TRIGGER" || true |
| |
| # Record and dump the results |
| dmesg | comm --nocheck-order -13 "$DMESG" - > "$LOG" || true |
