check return value of dladdr

[lugia-kun]

dladdr leave unchanged for info (on Linux), when it returns error (0).

This can be checked easily with following C code, which causes a segmentation fault before this change.

#define _GNU_SOURCE
#include <dlfcn.h>
#include <stdlib.h>
#include <string.h>

int main(int argc, char** argv)
{
  Dl_info info;
  memset(&info, 0xfe, sizeof(info)); /* fill with inaccessible address */
  dladdr(NULL, &info);
  return 0;
}

[rdp]

Any way this could get applied?

[josch]

@rdp Which distro are you using? You might have more luck approaching the package maintainers of your distro and ask them if they can apply that patch.

[rdp]

Ahh its unmaintained #84 durn...

[rdp]

@josch Ubuntu so maybe you could help? :)

[josch]

I'm the package maintainer in Debian. So I can apply this fix and then Ubuntu will (hopefully) copy it over from Debian unstable for the jammy release. I am not a Ubuntu developer, so I cannot directly make changes there.

[josch]

@rdp I now added the changes from this pull request to the version that Debian ships. It should end up in Ubuntu at some point as well.

@lugia-kun I also added a test case using your code above. Please consider adding the test case to this pull request as well: https://sources.debian.org/src/fakechroot/2.20.1+ds-1/debian/patches/0008-check-return-value-of-dladdr.patch/

[rdp]

Thanks!

On Thu, Nov 11, 2021 at 1:05 PM josch @.***> wrote:

@rdp https://github.com/rdp I now added the changes from this pull request to the version that Debian ships. It should end up in Ubuntu at some point as well.

@lugia-kun https://github.com/lugia-kun I also added a test case using your code above. Please consider adding the test case to this pull request as well: https://sources.debian.org/src/fakechroot/2.20.1+ds-1/debian/patches/0008-check-return-value-of-dladdr.patch/

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[lugia-kun]

Fixes crystal-lang/crystal#9209

Thanks for adding a test case.

[josch]

Hi @lugia-kun, could you mark test/t/dladdr.t as executable with chmod +x test/t/dladdr.t and add this change to this pull request? Thanks!