{"action":"opened","issue":{"url":"https://api.github.com/repos/openwrt/packages/issues/1660","labels_url":"https://api.github.com/repos/openwrt/packages/issues/1660/labels{/name}","comments_url":"https://api.github.com/repos/openwrt/packages/issues/1660/comments","events_url":"https://api.github.com/repos/openwrt/packages/issues/1660/events","html_url":"https://github.com/openwrt/packages/issues/1660","id":101189213,"number":1660,"title":"collectd 5.5.0 dns module segfaults (with kernel 4.1.x ?)","user":{"login":"hnyman","id":7926856,"avatar_url":"https://avatars.githubusercontent.com/u/7926856?v=3","gravatar_id":"","url":"https://api.github.com/users/hnyman","html_url":"https://github.com/hnyman","followers_url":"https://api.github.com/users/hnyman/followers","following_url":"https://api.github.com/users/hnyman/following{/other_user}","gists_url":"https://api.github.com/users/hnyman/gists{/gist_id}","starred_url":"https://api.github.com/users/hnyman/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/hnyman/subscriptions","organizations_url":"https://api.github.com/users/hnyman/orgs","repos_url":"https://api.github.com/users/hnyman/repos","events_url":"https://api.github.com/users/hnyman/events{/privacy}","received_events_url":"https://api.github.com/users/hnyman/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-08-15T16:47:46Z","updated_at":"2015-08-15T16:47:46Z","closed_at":null,"body":"I get segfault from collectd 5.5.0 if the DNS statistics plugin is enabled. \r\nar71xx / WNDR3700\r\n\r\nMy personal build included collectd 5.5.0 for a few weeks before the #1575 updated it officially. \r\n\r\n* collectd DNS plugin works ok upto trunk build 46391 (July 16th) with kernel 3.18.18.\r\n* collectd DNS plugin segfaults with all later builds with kernel 4.1.x. Earliest segfaulting build that I have is r46441 (Jul 22) with kernel 4.1.3\r\n\r\n```\r\n[  104.435977] \r\n[  104.435977] do_page_fault(): sending SIGSEGV to collectd for invalid write access to 76db3ae8\r\n[  104.444585] epc = 76f6ef30 in dns.so[76f6e000+14000]\r\n[  104.449597] ra  = 0040f084 in collectd[400000+30000]\r\n[  104.454602] \r\n```\r\nDisabling dns plugin in Luci statistics enables collectd to stay running.\r\n\r\nThere has been no commits to dns.c at the collectd repo for 9 months, so I see nothing obvious from that angle. Similarly, there are no obviously related changes in Luci during 16-22 July. Thus I highlight the kernel change as my guess as a possible reason.\r\n\r\nI am rather uncertain into which direction to go looking for a solution. I found one earlier discussion with references to lua and collectd and a possible solution related to gcc compilation options, so I am including that link as a reference http://stackoverflow.com/questions/12750264/got-sigsegv-while-calling-require-lsqlite3-with-lua-5-1-5 \r\n\r\nI might try looking for more exact regression window inside 16-22 July."}}