Signal 6

[Doug Hardie]

> On 29 June 2018, at 08:57, Michael Sierchio <kudzu at tenebras.com> wrote:
> 
> One way to find out is to register a handler for SIGABRT and print and flush the context.

Registering a handler is easy.  The stack is shown through backtrace().  However, if the backtrace is in the main code, it shows the complete stack.  If it is in an interrupt handler function then it only shows the call to backtrace.  Is there some way to give it access to the complete stack?

> 
> On Fri, Jun 29, 2018 at 8:56 AM, Michael Sierchio <kudzu at tenebras.com> wrote:
> Are there process limits?
> 
> malloc() will call abort() if internal structures are munged (e.g., by heap overflow).
> 
> calling free() on a corrupted pointer does that reliably
> 
> is the root partition big enough for the dump?
> 
> = M
> 
> On Fri, Jun 29, 2018 at 8:40 AM, Doug Hardie <bc979 at lafn.org> wrote:
> I have a daemon process that runs forever (almost).  Something is killing it with a signal 6, but no core dump is done.  If I manually kill it with kill -6, then the log message shows core dumped and a core file is created.  The process has no reference to SIG_ABRT, so I suspect the kernel is doing the kill and is overriding the core dump.  I have previously encountered a similar issue where swap space was running out and the kernel killed this process without a core dump.  In that case there were quite a few messages logged about swap space issues before the process was killed.  There are no swap messages logged this time.
> 
> /etc/sysctl.conf contains:
> kern.sugid_coredump=1
> kern.corefile=/crash/%N.core
> 
> /crash is a directory in the root file system.
> 
> Other than swap issues, when would the kernel kill a process without a core dump?
> 
> -- Doug
> 
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> -- 
> "Well," Brahma said, "even after ten thousand explanations, a fool is no wiser, but an intelligent person requires only two thousand five hundred."
> 
> - The Mahābhārata
> 
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> 
> -- 
> "Well," Brahma said, "even after ten thousand explanations, a fool is no wiser, but an intelligent person requires only two thousand five hundred."
> 
> - The Mahābhārata