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[Launchpad Bug Tracker <1879987@xxxxxxxxxxxxxxxxxx>]

You have been subscribed to a public bug by Guilherme G. Piccoli (gpiccoli):

[Impact]

* Currently, if users provide the wrong console in kernel command-line
(like console=ttyS1, when the right one is ttyS0) *and* "quiet"
parameter is not provided, we may face an infinite loop on initramfs-
tools, effectively blocking the boot.

* Details are: the _log_msg() functions is "void" typed, which means it returns whatever its last command returns; this function is the basic building block for all error/warning messages in initramfs-tools. In case a bad console was provided to kernel on command-line, printf (and apparently all write()-related functions) returns error, and so this error is carried over in _log_msg().
 
* Happens that checkfs() function has a loop that runs forever in this scenario (*if* fsck is not present in initramfs, and obviously if "quiet" is not provided in the command-line). The situation is easily reproducible.

* This SRU proposes a pretty simple fix: return zero on _log_msg(). We
should definitely not brake the boot due to error log functions.


[Test Case]

* To reproduce this, one must boot a system (virtual machine is good)
with the wrong console set on kernel command-line through the "console="
parameter *and* not pass the "quiet" parameter.

* Also, e2fsck tool shouldn't be present in the initrd - for that, the
6th field of /etc/fstab (fs_passno) should be 0 and initrd must be
recreated after that. This is the default in Ubuntu, though.


[Regression Potential]

* The regression potential is small, we're just returning 0 after a
printf that is executed in error paths, so I don't expect any issues
from that. But in case something bad happens after this change, I expect
a more friendly" breakage, like an initramfs panic (drop to a shell),
not a silent failure or boot-loop.

** Affects: initramfs-tools (Ubuntu)
     Importance: High
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress

** Affects: initramfs-tools (Ubuntu Trusty)
     Importance: Low
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: Won't Fix

** Affects: initramfs-tools (Ubuntu Xenial)
     Importance: High
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress

** Affects: initramfs-tools (Ubuntu Bionic)
     Importance: High
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress

** Affects: initramfs-tools (Ubuntu Eoan)
     Importance: Low
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: Won't Fix

** Affects: initramfs-tools (Ubuntu Focal)
     Importance: High
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress

** Affects: initramfs-tools (Ubuntu Groovy)
     Importance: High
     Assignee: Guilherme G. Piccoli (gpiccoli)
         Status: In Progress


** Tags: seg sts
-- 
machine get stuck at boot if specified 'console=ttyS* ' doesn't exist.
https://bugs.launchpad.net/bugs/1879987
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