which limit is hit here?

[Per olof Ljungmark]

On 02/15/18 08:56, Michael Schuster wrote:
> Hi Per,
> 
> On Thu, Feb 15, 2018 at 8:41 AM, Per olof Ljungmark <peo at nethead.se
> <mailto:peo at nethead.se>> wrote:
> 
>     Hi,
> 
>     A process "squatter" from Cyrus-IMAP version 2.5.11 exits with signal
>     11. The purpose of the process is to create an index of the content in a
>     mailbox.
> 
>     On large mailboxes, squatter coredumps, the final message from truss
>     reads:
> 
>     mmap(0x0,700448768,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANON,-1,0x0) =
>     34783363072 (0x819400000)
>     mmap(0x0,936334732,PROT_READ,MAP_SHARED,107,0x0) = 35483811840
>     (0x843000000)
>     SIGNAL 11 (SIGSEGV)
>     process killed, signal = 11 (core dumped)
> 
> 
> to me this looks like the error is happening *after* mmap() returned
> successfully - most likely because "someone" miscalculates some pointer
> and tries to access an unmapped address. Maybe (but that's conjecture),
> PROT_READ is wrong here and someone is attempting to write to that
> mapped region; I'm not 100% sure though whether that'd actually trigger
> SIGSEGV.
> 
> I'd suggest you do something like
> $ gdb squatter core
> (gdb) bt
> 
> and look at the output, and maybe go to the maintainers of Cyrus-IMAP... 

Hi,

gdb says,

(gdb) bt
#0  0x00000000004049cc in ?? ()
#1  0x0000000803456da4 in ?? ()
#2  0x0000000804445130 in ?? ()
#3  0x003875e5ffffcb00 in ?? ()
#4  0x00000008047e7008 in ?? ()
#5  0x00000008047e7048 in ?? ()
#6  0x00000001040000c0 in ?? ()
#7  0x0000000810800000 in ?? ()
#8  0x0000000200000045 in ?? ()
#9  0x000000083a400000 in ?? ()
#10 0x00000008047e8e98 in ?? ()
#11 0x00000000000003bb in ?? ()
#12 0x00000008047e8eb8 in ?? ()
#13 0x00000000000000bf in ?? ()
#14 0x0ffd2a151071e550 in ?? ()
#15 0x000000bf00000002 in ?? ()
#16 0x37cf558c1298d1e7 in ?? ()
#17 0x0135682800000000 in ?? ()
#18 0x02e00a0e020d0336 in ?? ()
#19 0x0487888c03b90d10 in ?? ()
#20 0x062618da0556e126 in ?? ()
#21 0x0000000006f31067 in ?? ()
#22 0x0000000000000000 in ?? ()