1 files changed, 33 insertions, 3 deletions

diff --git a/fs/exec.c b/fs/exec.c
index cece8c14f377..28e3b5eb2f4a 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -984,7 +984,7 @@ int kernel_read_file_from_fd(int fd, void **buf, loff_t *size, loff_t max_size,
 	struct fd f = fdget(fd);
 	int ret = -EBADF;
 
-	if (!f.file)
+	if (!f.file || !(f.file->f_mode & FMODE_READ))
 		goto out;
 
 	ret = kernel_read_file(f.file, buf, size, max_size, id);
@@ -1011,7 +1011,7 @@ static int exec_mmap(struct mm_struct *mm)
 	/* Notify parent that we're no longer interested in the old VM */
 	tsk = current;
 	old_mm = current->mm;
-	mm_release(tsk, old_mm);
+	exec_mm_release(tsk, old_mm);
 
 	if (old_mm) {
 		sync_mm_rss(old_mm);
@@ -1028,10 +1028,23 @@ static int exec_mmap(struct mm_struct *mm)
 		}
 	}
 	task_lock(tsk);
+
+	local_irq_disable();
 	active_mm = tsk->active_mm;
-	tsk->mm = mm;
 	tsk->active_mm = mm;
+	tsk->mm = mm;
+	/*
+	 * This prevents preemption while active_mm is being loaded and
+	 * it and mm are being updated, which could cause problems for
+	 * lazy tlb mm refcounting when these are updated by context
+	 * switches. Not all architectures can handle irqs off over
+	 * activate_mm yet.
+	 */
+	if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
+		local_irq_enable();
 	activate_mm(active_mm, mm);
+	if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM))
+		local_irq_enable();
 	tsk->mm->vmacache_seqnum = 0;
 	vmacache_flush(tsk);
 	task_unlock(tsk);
@@ -1792,6 +1805,9 @@ static int __do_execve_file(int fd, struct filename *filename,
 		goto out_unmark;
 
 	bprm->argc = count(argv, MAX_ARG_STRINGS);
+	if (bprm->argc == 0)
+		pr_warn_once("process '%s' launched '%s' with NULL argv: empty string added\n",
+			     current->comm, bprm->filename);
 	if ((retval = bprm->argc) < 0)
 		goto out;
 
@@ -1816,6 +1832,20 @@ static int __do_execve_file(int fd, struct filename *filename,
 	if (retval < 0)
 		goto out;
 
+	/*
+	 * When argv is empty, add an empty string ("") as argv[0] to
+	 * ensure confused userspace programs that start processing
+	 * from argv[1] won't end up walking envp. See also
+	 * bprm_stack_limits().
+	 */
+	if (bprm->argc == 0) {
+		const char *argv[] = { "", NULL };
+		retval = copy_strings_kernel(1, argv, bprm);
+		if (retval < 0)
+			goto out;
+		bprm->argc = 1;
+	}
+
 	retval = exec_binprm(bprm);
 	if (retval < 0)
 		goto out;