On Fri 30-06-17 11:59:37, Anshuman Khandual wrote: > Hello, > > execve() system call should support argument length of > MAX_ARG_STRLEN (PAGE_SIZE * 32). On 64K page size systems, we > are not able to pass 32 * PAGE_SIZE arguments into the execve() > system call because of the following reasons. > > * struct linux_binprm's vma starts with a size of PAGE_SIZE > > vma->vm_end = STACK_TOP_MAX; > vma->vm_start = vma->vm_end - PAGE_SIZE; > > * The VMA expands as much depending upon the argument size. So > for 32 * PAGE_SIZE argument, it becomes 33 * PAGE_SIZE. > > * 33 * PAGE_SIZE with 64K pages fails the following test in > get_arg_page() function. 33 * PAGE_SIZE is more than 2MB > (8 MB /4) with 64K page size. > > if (size > READ_ONCE(rlim[RLIMIT_STACK].rlim_cur) / 4) > > * Right now RLIMIT_STACK is hard coded 8MB which does not take > PAGE_SIZE into account. > > Wondering what should be the solution for this problem ? > > * Change the default stack size from 8MB ?
just increase the ulimit if you want to use such a large arguments. > * Change the ratio test from 1/4th ? -- Michal Hocko SUSE Labs
