Ow Mun Heng said: [snip]
The author then compares the results with that of BSD eg: OpenBSD and FreeBSD IIRC, and notes that on a system with Pentium 90 w/ 32MB Ram, on using the forkbomb, doesn't bring the system down to it's knees.
Following the discussion on the -devel list, the BSDs aren't immune.
https://www.redhat.com/archives/fedora-devel-list/2005-March/msg01201.html
I gave a try to "while(1) fork();" on OpenBSD (SS5, 64MB RAM). You can't go much simpler than that. Results:
Running as normal user, max number of processes is limited to 64 by default, load average went to 50-something. Perfectly able to kill offending process(es).
Running as root, max number of processes is limited to 340, load average went to almost 300. Not able to do much, since root couldn't create any new processes (in order to kill existing), but top worked, and already running processes worked. Anyhow, if somebody does fork bomb as root, he could just as well type "halt" or wipe out the disk or do some other irreversable damage.
The maximum number of processes per user is hard coded in OpenBSD kernel. It is 340 for root, and 64/128 for normal users in my generic kernel (soft limit is 64, hard limit is 128). If you want more either for root or normal users, you need to recompile the kernel. In *BSD world, recompiling the kernel is something you do twice a day anyhow, so this isn't much of a problem ;-)
For those interested, these are ulimits on stock OpenBSD (user and root, soft and hard).
$ ulimit -Sa core file size (blocks, -c) unlimited data seg size (kbytes, -d) 76800 file size (blocks, -f) unlimited max locked memory (kbytes, -l) 28430 max memory size (kbytes, -m) 84964 open files (-n) 64 pipe size (512 bytes, -p) 1 stack size (kbytes, -s) 4096 cpu time (seconds, -t) unlimited max user processes (-u) 64 virtual memory (kbytes, -v) 80896
$ ulimit -Ha core file size (blocks, -c) unlimited data seg size (kbytes, -d) 131072 file size (blocks, -f) unlimited max locked memory (kbytes, -l) 85292 max memory size (kbytes, -m) 85292 open files (-n) 1024 pipe size (512 bytes, -p) 1 stack size (kbytes, -s) 131072 cpu time (seconds, -t) unlimited max user processes (-u) 128 virtual memory (kbytes, -v) 262144
# ulimit -Sa core file size (blocks, -c) unlimited data seg size (kbytes, -d) 131072 file size (blocks, -f) unlimited max locked memory (kbytes, -l) 28430 max memory size (kbytes, -m) 84964 open files (-n) 128 pipe size (512 bytes, -p) 1 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 340 virtual memory (kbytes, -v) 139264
# ulimit -Ha core file size (blocks, -c) unlimited data seg size (kbytes, -d) 131072 file size (blocks, -f) unlimited max locked memory (kbytes, -l) 85292 max memory size (kbytes, -m) 85292 open files (-n) 1024 pipe size (512 bytes, -p) 1 stack size (kbytes, -s) 131072 cpu time (seconds, -t) unlimited max user processes (-u) 340 virtual memory (kbytes, -v) 262144
-- Aleksandar Milivojevic <amilivojevic@xxxxxx> Pollard Banknote Limited Systems Administrator 1499 Buffalo Place Tel: (204) 474-2323 ext 276 Winnipeg, MB R3T 1L7
