tree df157ccec202fcf396df4cb1110dd8f48766da15
parent a18c3339c8d8038377a7ba0a5d0f845924ec1490
author William Lallemand <wlallemand@haproxy.org> 1658357563 +0200
committer William Lallemand <wlallemand@haproxy.org> 1658357563 +0200

BUG/MEDIUM: mworker: proc_self incorrectly set crashes upon reload

When updating from 2.4 to 2.6, the child->reloads++ instruction changed
place, resulting in a former worker from the 2.4 process, still
identified as a current worker once in 2.6, because its reload counter
is still 0.

Unfortunately this counter is used to chose the mworker_proc structure
that will be used for the new worker.

What happens next, is that the mworker_proc structure of the previous
process is selected, and this one has ipc_fd[1] set to -1, because this
structure was supposed to be in the master.

The process then forks, and mworker_sockpair_register_per_thread() tries
to register ipc_fd[1] which is set to -1, instead of the fd of the new
socketpair.

This patch fixes the issue by checking if child->pid is equal to -1 when
selecting proc_self. This way we could be sure it wasn't a previous
process.

Should fix issue #1785.

This must be backported as far as 2.4 to fix the issue related to the
reload computation difference. However backporting it in every stable
branch will enforce the reload process.