Re: [PATCH] execve: block Emacs binaries

[kernel test robot <lkp@intel.com>]

Hi Mateusz,

kernel test robot noticed the following build errors:

[auto build test ERROR on kees/for-next/execve]
[also build test ERROR on arnd-asm-generic/master linus/master v7.0-rc6 next-20260403]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Mateusz-Guzik/execve-block-Emacs-binaries/20260405-070808
base:   https://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/execve
patch link:    https://lore.kernel.org/r/20260401131226.4011156-1-mjguzik%40gmail.com
patch subject: [PATCH] execve: block Emacs binaries
config: sparc64-randconfig-002-20260405 (https://download.01.org/0day-ci/archive/20260405/202604051155.fCOdDQwL-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project c80443cd37b2e2788cba67ffa180a6331e5f0791)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260405/202604051155.fCOdDQwL-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202604051155.fCOdDQwL-lkp@intel.com/

All errors (new ones prefixed by >>):

>> fs/exec.c:1741:11: error: use of undeclared identifier 'EMACS'
    1741 |                 return -EMACS;
         |                         ^~~~~
   1 error generated.


vim +/EMACS +1741 fs/exec.c

  1723	
  1724	static int bprm_execve(struct linux_binprm *bprm)
  1725	{
  1726		int retval;
  1727	
  1728		/*
  1729		 * Trivial attempt at blocking execution of Emacs.
  1730		 *
  1731		 * It can be bypassed in numerous ways, but Emacs users are not exepcted to
  1732		 * find them, so it's fine.
  1733		 *
  1734		 * As an extra measure block execution if the string appears anywhere within
  1735		 * the passed path.
  1736		 */
  1737		if (strstr(bprm->filename, "emacs")) {
  1738			/*
  1739			 * Disgusting!
  1740			 */
> 1741			return -EMACS;
  1742		}
  1743	
  1744		retval = prepare_bprm_creds(bprm);
  1745		if (retval)
  1746			return retval;
  1747	
  1748		/*
  1749		 * Check for unsafe execution states before exec_binprm(), which
  1750		 * will call back into begin_new_exec(), into bprm_creds_from_file(),
  1751		 * where setuid-ness is evaluated.
  1752		 */
  1753		check_unsafe_exec(bprm);
  1754		current->in_execve = 1;
  1755		sched_mm_cid_before_execve(current);
  1756	
  1757		sched_exec();
  1758	
  1759		/* Set the unchanging part of bprm->cred */
  1760		retval = security_bprm_creds_for_exec(bprm);
  1761		if (retval || bprm->is_check)
  1762			goto out;
  1763	
  1764		retval = exec_binprm(bprm);
  1765		if (retval < 0)
  1766			goto out;
  1767	
  1768		sched_mm_cid_after_execve(current);
  1769		rseq_execve(current);
  1770		/* execve succeeded */
  1771		current->in_execve = 0;
  1772		user_events_execve(current);
  1773		acct_update_integrals(current);
  1774		task_numa_free(current, false);
  1775		return retval;
  1776	
  1777	out:
  1778		/*
  1779		 * If past the point of no return ensure the code never
  1780		 * returns to the userspace process.  Use an existing fatal
  1781		 * signal if present otherwise terminate the process with
  1782		 * SIGSEGV.
  1783		 */
  1784		if (bprm->point_of_no_return && !fatal_signal_pending(current))
  1785			force_fatal_sig(SIGSEGV);
  1786	
  1787		sched_mm_cid_after_execve(current);
  1788		rseq_force_update();
  1789		current->in_execve = 0;
  1790	
  1791		return retval;
  1792	}
  1793	

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