1 files changed, 60 insertions, 62 deletions

diff --git a/fs/exec.c b/fs/exec.c
index fd774c7cb483..8875dd10ae7a 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -74,6 +74,8 @@ static DEFINE_RWLOCK(binfmt_lock);
 void __register_binfmt(struct linux_binfmt * fmt, int insert)
 {
 	BUG_ON(!fmt);
+	if (WARN_ON(!fmt->load_binary))
+		return;
 	write_lock(&binfmt_lock);
 	insert ? list_add(&fmt->lh, &formats) :
 		 list_add_tail(&fmt->lh, &formats);
@@ -266,7 +268,7 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
 	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
 	vma->vm_end = STACK_TOP_MAX;
 	vma->vm_start = vma->vm_end - PAGE_SIZE;
-	vma->vm_flags = VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
+	vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
 	vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
 	INIT_LIST_HEAD(&vma->anon_vma_chain);
 
@@ -1365,18 +1367,18 @@ out:
 }
 EXPORT_SYMBOL(remove_arg_zero);
 
+#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
 /*
  * cycle the list of binary formats handler, until one recognizes the image
  */
 int search_binary_handler(struct linux_binprm *bprm)
 {
-	unsigned int depth = bprm->recursion_depth;
-	int try,retval;
+	bool need_retry = IS_ENABLED(CONFIG_MODULES);
 	struct linux_binfmt *fmt;
-	pid_t old_pid, old_vpid;
+	int retval;
 
 	/* This allows 4 levels of binfmt rewrites before failing hard. */
-	if (depth > 5)
+	if (bprm->recursion_depth > 5)
 		return -ELOOP;
 
 	retval = security_bprm_check(bprm);
@@ -1387,71 +1389,67 @@ int search_binary_handler(struct linux_binprm *bprm)
 	if (retval)
 		return retval;
 
+	retval = -ENOENT;
+ retry:
+	read_lock(&binfmt_lock);
+	list_for_each_entry(fmt, &formats, lh) {
+		if (!try_module_get(fmt->module))
+			continue;
+		read_unlock(&binfmt_lock);
+		bprm->recursion_depth++;
+		retval = fmt->load_binary(bprm);
+		bprm->recursion_depth--;
+		if (retval >= 0 || retval != -ENOEXEC ||
+		    bprm->mm == NULL || bprm->file == NULL) {
+			put_binfmt(fmt);
+			return retval;
+		}
+		read_lock(&binfmt_lock);
+		put_binfmt(fmt);
+	}
+	read_unlock(&binfmt_lock);
+
+	if (need_retry && retval == -ENOEXEC) {
+		if (printable(bprm->buf[0]) && printable(bprm->buf[1]) &&
+		    printable(bprm->buf[2]) && printable(bprm->buf[3]))
+			return retval;
+		if (request_module("binfmt-%04x", *(ushort *)(bprm->buf + 2)) < 0)
+			return retval;
+		need_retry = false;
+		goto retry;
+	}
+
+	return retval;
+}
+EXPORT_SYMBOL(search_binary_handler);
+
+static int exec_binprm(struct linux_binprm *bprm)
+{
+	pid_t old_pid, old_vpid;
+	int ret;
+
 	/* Need to fetch pid before load_binary changes it */
 	old_pid = current->pid;
 	rcu_read_lock();
 	old_vpid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));
 	rcu_read_unlock();
 
-	retval = -ENOENT;
-	for (try=0; try<2; try++) {
-		read_lock(&binfmt_lock);
-		list_for_each_entry(fmt, &formats, lh) {
-			int (*fn)(struct linux_binprm *) = fmt->load_binary;
-			if (!fn)
-				continue;
-			if (!try_module_get(fmt->module))
-				continue;
-			read_unlock(&binfmt_lock);
-			bprm->recursion_depth = depth + 1;
-			retval = fn(bprm);
-			bprm->recursion_depth = depth;
-			if (retval >= 0) {
-				if (depth == 0) {
-					trace_sched_process_exec(current, old_pid, bprm);
-					ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
-				}
-				put_binfmt(fmt);
-				allow_write_access(bprm->file);
-				if (bprm->file)
-					fput(bprm->file);
-				bprm->file = NULL;
-				current->did_exec = 1;
-				proc_exec_connector(current);
-				return retval;
-			}
-			read_lock(&binfmt_lock);
-			put_binfmt(fmt);
-			if (retval != -ENOEXEC || bprm->mm == NULL)
-				break;
-			if (!bprm->file) {
-				read_unlock(&binfmt_lock);
-				return retval;
-			}
+	ret = search_binary_handler(bprm);
+	if (ret >= 0) {
+		trace_sched_process_exec(current, old_pid, bprm);
+		ptrace_event(PTRACE_EVENT_EXEC, old_vpid);
+		current->did_exec = 1;
+		proc_exec_connector(current);
+
+		if (bprm->file) {
+			allow_write_access(bprm->file);
+			fput(bprm->file);
+			bprm->file = NULL; /* to catch use-after-free */
 		}
-		read_unlock(&binfmt_lock);
-#ifdef CONFIG_MODULES
-		if (retval != -ENOEXEC || bprm->mm == NULL) {
-			break;
-		} else {
-#define printable(c) (((c)=='\t') || ((c)=='\n') || (0x20<=(c) && (c)<=0x7e))
-			if (printable(bprm->buf[0]) &&
-			    printable(bprm->buf[1]) &&
-			    printable(bprm->buf[2]) &&
-			    printable(bprm->buf[3]))
-				break; /* -ENOEXEC */
-			if (try)
-				break; /* -ENOEXEC */
-			request_module("binfmt-%04x", *(unsigned short *)(&bprm->buf[2]));
-		}
-#else
-		break;
-#endif
 	}
-	return retval;
-}
 
-EXPORT_SYMBOL(search_binary_handler);
+	return ret;
+}
 
 /*
  * sys_execve() executes a new program.
@@ -1541,7 +1539,7 @@ static int do_execve_common(const char *filename,
 	if (retval < 0)
 		goto out;
 
-	retval = search_binary_handler(bprm);
+	retval = exec_binprm(bprm);
 	if (retval < 0)
 		goto out;