[squid-dev] Squid 3.5.23: crash in Comm::DoSelect

[Amos Jeffries]

FYI: Squid-3.5.23 does not exist yet. What is the output of "squid -v" ?

On 18/10/2016 5:01 a.m., oleg gv wrote:
> I have big traffic (at least 100 computers) , and squid often crashed in
> Comm::DoSelect(int msec) function.
> I have interception mode and NAT redirect.
> 
> In coredump I saw then bug is in next fragment of code:
> 
> 446│         for (size_t loopIndex = 0; loopIndex < nfds; ++loopIndex) {
> 447│             fde *F;
> 448│             int revents = pfds[loopIndex].revents;
> 449│             fd = pfds[loopIndex].fd;
> 450│
> 451│             if (fd == -1)
> 452│                 continue;
> 453│
> 454├>            if (fd_table[fd].flags.read_pending)
> 455│                 revents |= POLLIN;
> 
> SIGSEGV occured often (about 1 time in a minute) in line 454 : fd=-66012128
> , loopindex=283
> 
> (gdb) p pfds[282]
> $17 = {fd = 291, events = 64, revents = 0}   -- looks ok
> 
> (gdb) p pfds[283]
> $18 = {fd = -66012128, events = 32595, revents = 0}  -- looks strange and
> spoiled
> 
> (gdb) p Biggest_FD
> $19 = 292
> 

What is the nfds value ?

It looks to me like only 282 FD have operations to perform on this I/O
cycle.

What I/O module is being used?

 src/comm/ModDevPoll.cc:Comm::DoSelect(int msec)
 src/comm/ModPoll.cc:Comm::DoSelect(int msec)


Amos