integer overflow in ipcs.c, do_shm()

[rudimeier]

/proc/sys/kernel/shmall gives a count of pages as size_t. This overflows when multiplying by pagesize:

ipc_print_size(unit == IPC_UNIT_DEFAULT ? IPC_UNIT_KB : unit,
               _("max total shared memory"),
               lim.shmall * getpagesize(), "\n", 0);

That's why ./tests/ts/ipcs/limits2 fails on systems where shmall is large enough.
The problem got a bit worse since 56692a6.

Don't know how this should be fixed. I guess the only real fix would be to use large integer arithmetics.

[rudimeier]

Thanks, but this fix still not works on x86_64 where size_t and unit64_t are the same.
For example on my system I have per default

$ cat /proc/sys/kernel/shmall
1152921504606846720 

which is 4611686018427386880 KB and greater than 2^64 bytes
so ipcs can't do it correctly:

$ ./ipcs -ml | grep "max total"
max total shared memory (kbytes) = 18014398509480960

[DerDakon]

I think I have hit the same thing on hppa with 2.36.2. The ipcs/limits2 test fails for me.

# cat limits2
check for difference between kernel and IPC
/proc/sys/kernel/shmmni kernel=, ipcs=4096
/proc/sys/kernel/shmall kernel=, ipcs=18014398509481980
/proc/sys/kernel/shmmax kernel=, ipcs=18014398509465599
#  cat /proc/sys/kernel/shmmni /proc/sys/kernel/shmall /proc/sys/kernel/shmmax
4096
18446744073692774399
18446744073692774399
# ipcs -ml
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 18014398509465599
max total shared memory (kbytes) = 18014398509481980
min seg size (bytes) = 1