Unaligned stack with Xcode 11.0 beta #848
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Some more details after debugging: libsodium throws a general protection fault due to an unaligned memory access in Arguments at time of unaligned access: |
stv0g
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The stack not being aligned is quite unexpected and sounds like a compiler bug. How did you compile it? What version of Xcode did you use? Any specific extra optimizations, or did you just use |
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Meanwhile, this code path has been disabled in the stable branch. |
Just plain
No special options for
$ pkgutil --pkg-info=com.apple.pkg.CLTools_Executables | grep version
version: 11.0.0.0.1.1563062694This is the latest beta of macOS Catalina. See also |
Disabled in stable, but not master / 0.18.0? |
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That's exactly what stable versions are for. Can you try different optimization levels, including no optimizations at all ( |
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I see the same results (
When compiling with |
355: Fix path to configure script r=kpp a=stv0g See #341 === jedisct1/libsodium#848 Co-authored-by: Steffen Vogel <post@steffenvogel.de>
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o_O What other tests are failing with |
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All fail with a segmentation fault: |
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Try the compiler version shipped with Xcode ( |
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I can confirm that all tests succeed when using compiler from my full Xcode installation. Here are again the versions: /Applications/Xcode.app/$ sudo xcode-select -s /Applications/Xcode.app/
$ /usr/bin/gcc --version
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/Library/Developer/CommandLineTools/SDKs/MacOSX10.15.sdk/usr/include/c++/4.2.1
Apple LLVM version 10.0.1 (clang-1001.0.46.4)
Target: x86_64-apple-darwin19.0.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/binState: /Applications/Xcode-beta.app/State: /Library/Developer/CommandLineTools/State: As you can see, Xcode uses Clang 10 while my Command Line Tools use Clang 11.. o_O I am downloading now Xcode 11 Beta 4. And try again. I assume that my Command Line Tools already have been updated automatically, while Xcode stayed at version 10. |
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Xcode 11 beta 4 ships with what Apple calls LLVM 11, but it's a different version than the one you reported. |
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I updated my previous comment with results using Xcode Beta 4. |
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So what's the state of the issue? |
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The compiler from both Xcode 11 Beta and the Command Line Tools produce code which segfaults in the I provided Apple some feedback via their Beta Feedback App. I am not entirely sure that this is a compiler bug. Looks strange to me, that only the |
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Mmmm... my version of |
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@jedisct1 Does this version work for you? |
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What about macOS Catalina 10.15 Beta (19A512f)? Is it the only difference in your envs? |
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It does, but I don't have a good CPU like yours. No AVX512 here. |
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This compiler version is completely broken; I installed it and the first project I compiled with it, that has nothing to do with libsodium, crashed the same way (unaligned stack). |
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Was it fixed in a new version of the compiler? |
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Unfortunately not. And nobody reported it on the Apple developer forums. |
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Compiling without optimizations ( |
jedisct1
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jedisct1
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Why did you close the issue then? |
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Unfortunately, keeping an issue opened here will not do anything, The solution is simply to use the stable version of Xcode. |
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Ok now it sounds as a resolution |
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With this version, dsvpn segfaults even before reaching the |
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Here's a test case, in case someone wants to report this to Apple so that it is fixed. #include <fcntl.h>
#include <netdb.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
typedef struct {
char d[16];
void *e;
struct { char b[5536]; } f;
} i;
void g(void) {
struct addrinfo hints, *k;
memset(&hints, 0, sizeof hints);
getaddrinfo(NULL, NULL, &hints, &k);
}
int main(void) {
puts("Hello world");
fflush(stdout);
close(open("/dev/null", O_RDONLY));
i context;
context.e = open;
printf("%p\n", context.d);
g();
return 0;
}cc -mavx -O2 a.c && ./a.outlldb ./a.out
run
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=EXC_I386_GPFLT)
frame #0: 0x00007fff65e73316 libdyld.dylib`stack_not_16_byte_aligned_error
libdyld.dylib`stack_not_16_byte_aligned_error:
-> 0x7fff65e73316 <+0>: movdqa %xmm0, (%rsp)The stack pointer becomes invalid even before we reach the This doesn't happen without AVX, or with stable versions of the compiler. |
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A workaround is to compile with |
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It seems like adding In the release notes here, you can see:
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The compiler emits invalid code. This has nothing to do with libsodium, see the test case above. |
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See https://forums.developer.apple.com/thread/121887 This compiler version is broken, has obviously received insufficient testing, and even with additional compilation flags, I wouldn’t recommend using it for anything serious. |
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FYI, this is still an issue with the release version of Catalina; as the above cross-refs show, it's showing up in a lot of other libraries, as well. (Hello from bcmyers/argonautica#20!) |
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FWIW, this issue appears fixed in Xcode 11.2 and the crate builds successfully with it. Note that if you had installed the command line tools, using |
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I can confirm that the suggestion by eliaslevy works as advertised. Thanks. |
During
make checkthepwhash_argon2iandpwhash_argon2idtests fail with a segmention fault.Tested on
0.18.0-RELEASEand fdfca24Compiler
Backtraces
pwhash_argon2i
pwhash_argon2id
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