Re: [patch 0/3] no MAX_ARG_PAGES -v2
From: Ollie Wild <hidden>
Date: 2007-06-14 20:59:21
Also in:
linux-arch, lkml
quoted hunk ↗ jump to hunk
@@ -1385,6 +1401,10 @@ int do_execve(char * filename, goto out; bprm->argv_len = env_p - bprm->p; + retval = expand_arg_vma(bprm); + if (retval < 0) + goto out; + retval = search_binary_handler(bprm,regs); if (retval >= 0) { /* execve success */
At this point bprm->argc hasn't been finalized yet. For example, the script binfmt reads the script header and adds additional arguments. The flush_old_exec() function is a better place to call this. I'm not 100% sure this is the right way to handle this, though. The problem isn't as simple as ensuring the stack doesn't overflow during argument allocation. We also need to ensure the program has sufficient stack space to run subsequently. Otherwise, the observable behavior is identical. Since we can't realistically predict acceptable stack availability requirements, some amount of uncertainty is always going to exist. A good heuristic, though, might be to limit argument size to a percentage (say 25%) of maximum stack size and validate this inside copy_strings(). Ollie -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>