From 6aa348826a4877d8b964476fed02cd59c76d2ac4 Mon Sep 17 00:00:00 2001 From: Dimitry Andric Date: Thu, 7 Jan 2016 22:19:12 +0000 Subject: Ensure safestack overflow test doesn't segfault Summary: In rL255491, the safestack overflow test was disabled for aarch64, since it "is currently failing on an AArch64 buildbot with a segfault, but it is currently passing on other configuration". While testing on FreeBSD on x86, I also encountered a segfault. This is because the `fct()` function actually writes before and after `buffer`, and on FreeBSD this crashes because `buffer` is usually allocated at the end of a page. That this runs correctly on Linux is probably just by accident. I propose to fix this by adding a pre and post buffer, to act as a safety zone. The pre and post buffers must be accessed in an 'unsafe' way, otherwise -fsanitize=safestack will allocate them on the safe stack, and they will not bookend `buffer` itself. Therefore, I create them large enough for `fct()`, and call it on both of them. On FreeBSD, this makes the test run as expected, without segfaulting, and I suppose this will also fix the segfault on AArch64. I do not have AArch64 testing capabilities, so if someone could try that out, I would be much obliged. Reviewers: pcc, kcc, zatrazz Subscribers: llvm-commits, aemerson, emaste Differential Revision: http://reviews.llvm.org/D15725 git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@257106 91177308-0d34-0410-b5e6-96231b3b80d8 --- test/safestack/overflow.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'test/safestack') diff --git a/test/safestack/overflow.c b/test/safestack/overflow.c index 27436947e..62f865369 100644 --- a/test/safestack/overflow.c +++ b/test/safestack/overflow.c @@ -17,9 +17,13 @@ void fct(volatile int *buffer) int main(int argc, char **argv) { + int prebuf[7]; int value1 = 42; int buffer[5]; int value2 = 42; + int postbuf[7]; + fct(prebuf + 1); + fct(postbuf + 1); fct(buffer); return value1 != 42 || value2 != 42; } -- cgit v1.2.3