Nagios Support Forum

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On 19/06/08 07:46 AM, Franky Van Liedekerke wrote:
> Hi all,
>
> I had some problems with history.cgi where it consistently coredumped on me.
> After some searching, it seems that history.c assumes that each line in
> nagios.log has a certain maximum lenght (MAX_INPUT_BUFFER) but some
> plugins write more info away there (like the check_oracle_health plugin
> in my case).
> But the issue is: when such a long line is found, history.c doesn't chop
> it off after MAX_INPUT_BUFFER characters and as such coredumps ...
> Solution: add the line
>
> input[MAX_INPUT_BUFFER]='\x0';
>
> at around line 551 in cgi/history.c (before the "strip(input);" line),
> so the code becomes:
>
> printf("\n");
>
> while(1){
>
> free(input);
>
> if(use_lifo==TRUE){
> if((input=pop_lifo())==NULL)
> break;
> }
> else{
> if((input=mmap_fgets(thefile))==NULL)
> break;
> }
>
> input[MAX_INPUT_BUFFER]='\x0';
> strip(input);
>
> This solves my problem for now, but I don't know if it is the correct
> solution of course ...

I don't have time to test, but it looks like the segfault is just a few
lines below:

strcpy(input_buffer2,input);

input_buffer2 has a static length of MAX_INPUT_BUFFER, so you should
rather use strncpy and limit to "MAX_INPUT_BUFFER-1" characters (so it
will be able to terminate it with a \0).

Your fix will work just as well, but changing strcpy to strncpy is more
obvious and use of strcpy is discouraged for that exact reason.

Thomas
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