Here's a patch for cronolog - same as what I submitted upstream [1], but there's some question if it will ever be merged given the lack of maintenance of cronolog. There's also some additional technical discussion around details of the bug [2].
[1] https://github.com/fordmason/cronolog/pull/5 [2] https://bugs.launchpad.net/debian/+source/cronolog/+bug/1770676 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 diff -Nru cronolog-1.6.2+rpk/debian/changelog cronolog-1.6.2+rpk/debian/changelog - --- cronolog-1.6.2+rpk/debian/changelog 2017-11-01 13:32:47.000000000 +0000 +++ cronolog-1.6.2+rpk/debian/changelog 2018-05-15 17:47:53.000000000 +0000 @@ -1,3 +1,10 @@ +cronolog (1.6.2+rpk-3) unstable; urgency=medium + + * Non-maintainer upload. + * Fix links broken by stat() on NULL pointer (Closes: #799170). + + -- Scott Emmons <sesail...@gmail.com> Tue, 15 May 2018 17:47:53 +0000 + cronolog (1.6.2+rpk-2) unstable; urgency=medium * QA upload diff -Nru cronolog-1.6.2+rpk/debian/patches/090_fix_broken_links.patch cronolog-1.6.2+rpk/debian/patches/090_fix_broken_links.patch - --- cronolog-1.6.2+rpk/debian/patches/090_fix_broken_links.patch 1970-01-01 00:00:00.000000000 +0000 +++ cronolog-1.6.2+rpk/debian/patches/090_fix_broken_links.patch 2018-05-15 17:47:53.000000000 +0000 @@ -0,0 +1,18 @@ +Index: cronolog-1.6.2+rpk/src/cronoutils.c +=================================================================== +--- cronolog-1.6.2+rpk.orig/src/cronoutils.c ++++ cronolog-1.6.2+rpk/src/cronoutils.c +@@ -195,11 +195,11 @@ create_link(char *pfilename, + { + struct stat stat_buf; + +- if (stat(prevlinkname, &stat_buf) == 0) ++ if (prevlinkname && stat(prevlinkname, &stat_buf) == 0) + { + unlink(prevlinkname); + } +- if (stat(linkname, &stat_buf) == 0) ++ if (linkname && stat(linkname, &stat_buf) == 0) + { + if (prevlinkname) { + rename(linkname, prevlinkname); diff -Nru cronolog-1.6.2+rpk/debian/patches/series cronolog-1.6.2+rpk/debian/patches/series - --- cronolog-1.6.2+rpk/debian/patches/series 2011-06-09 01:41:16.000000000 +0000 +++ cronolog-1.6.2+rpk/debian/patches/series 2018-05-15 17:47:53.000000000 +0000 @@ -4,3 +4,4 @@ 060_cronosplit_manpage_correction.diff 070_manpages_fixes.diff 080_cronosplit_utime.diff +090_fix_broken_links.patch -----BEGIN PGP SIGNATURE----- iQIzBAEBCgAdFiEE//XzeneJP7JXus+2Ud1pESCK794FAlr7R0kACgkQUd1pESCK 794onRAApqg4rsVoXCG5dlERhDiqywm5EzOJEtmIi1DS8tTi7jZ+mj1MbPlUUGeq E5t3Z8uzV9Qi0UEdQqC/LUbWZ76JSzpPOt0bK956MZzZcDCgxRt7EcV1wX3+7Yu5 6TH7C2dYaZ+eWdXzblu2GRZAAUWGwxuRgFTT0ueskVPRU82dtX3uQdLugdzNu7Lf e0HTUlEv8kuCdlI6G6fWll1ygbWKVvogrelfifwL8msy+3ZSPkb7PtT19PP4RdBA 2FjhM+RnsDXrpWQbUc9N12iXPqcAo8pQa3Bh+LYIe6vQBtlB9SdK3/IHl0PUXhAG Kc8QhLZlHDYZVv6R3WFHeAjmLUSTcXXfmiEF/qwiMtGMMnbqwNJiO25GPbrdh2bV 96sa5dwkSNCEd6zxhEKAdrb18y/DSSFofOhNOmZoauHbwb65Cw4WHkgPlmFVwDvw UsAGORiOK8gLG1MqTGOSX4Toku40G7YGWlYVczyP+suDB2wK6fxZVKVAXAKztlrr 19n+BZgi0vEDWm7ZJcgCL0K6wcPdSdOBOEttrhaBrAHb/BE5FAERVQ/7lmbkspJZ gXB7pAfUCOAh2Juj1/esZWig2sv+5GxTQEZphP2lg6wHvNjzD1Bit4M3uvDzzz+P tvZbNgsKo4JiDtSfBUcJctjXZ0ADnjURRzl24SUkA9mJcsVM3pg= =lYFZ -----END PGP SIGNATURE-----