系统调用可以导致Linux中的系统恐慌吗？

Question

Please don't consider syscalls due to calls to panic() etc., which are actually supposed to panic the system. I am more interested in general purpose system calls such as Socket , read, write etc. If such syscalls do cause a panic, then is this a kernel bug? My understanding is that it should be a kernel bug. If passed with wrong arguments then system-call should just abort not panic the complete system.

Answer 1

Strangely enough, this is not 100% correct.

Yes, input to system calls by a non privileged user should not cause a panic unless there is a bug in the kernel or a hardware malfunction (such as broken RAM chips).

However, this not true for a privileged user (such as root). Consider the write(2) system call, when applied to /dev/mem by a privileged user (root being the obvious example) - there is nothing stopping you from overwriting kernel memory with it.

Unix is like that - it gives you the full length of the rope to hang yourself easily, if this is what you wish to do :-)

Answer 2

Of course, the kernel must check the syscall parameters, user permissions, resources availability and handle issues like concurrency in order to avoid crash at all costs. The bottomline is that a simple user (even root, ideally - but as mentionned by gby this is difficult since root can have direct access to the physical address space) should never be able to crash the system, no matter how hard she tries.