From 15934e2c8123ee307574059d7c3f6a5916c054c9 Mon Sep 17 00:00:00 2001
From: Dave Reisner <dreisner@archlinux.org>
Date: Sat, 19 Apr 2014 13:22:35 -0400
Subject: [PATCH] implement a union to pad out file_handle

Cases where name_to_handle_at is used allocated the full struct to be
MAX_HANDLE_SZ, and assigned this size to handle_bytes. This is wrong
since handle_bytes should describe the length of the flexible array
member and not the whole struct.

Define a union type which includes sufficient padding to allow
assignment of MAX_HANDLE_SZ to be correct.

(cherry picked from commit 370c860f748d149097710dc7952a64f627db9de7)

Conflicts:
	src/shared/util.h

(cherry picked from commit 91795825a093331ef136be1d630c5fcad299dfe8)

Conflicts:
	src/libudev/libudev-monitor.c
	src/shared/util.h
---
 src/readahead/readahead-common.c |  6 ++----
 src/shared/util.h                |  6 ++++++
 src/tmpfiles/tmpfiles.c          | 11 ++++-------
 3 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/readahead/readahead-common.c b/src/readahead/readahead-common.c
index aea1fbeea4..1edf9cc33c 100644
--- a/src/readahead/readahead-common.c
+++ b/src/readahead/readahead-common.c
@@ -75,7 +75,7 @@ int fs_on_ssd(const char *p) {
         if (major(st.st_dev) == 0) {
                 _cleanup_fclose_ FILE *f = NULL;
                 int mount_id;
-                struct file_handle *h;
+                union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ, };
 
                 /* Might be btrfs, which exposes "ssd" as mount flag if it is on ssd.
                  *
@@ -83,9 +83,7 @@ int fs_on_ssd(const char *p) {
                  * and then lookup the mount ID in mountinfo to find
                  * the mount options. */
 
-                h = alloca(MAX_HANDLE_SZ);
-                h->handle_bytes = MAX_HANDLE_SZ;
-                r = name_to_handle_at(AT_FDCWD, p, h, &mount_id, AT_SYMLINK_FOLLOW);
+                r = name_to_handle_at(AT_FDCWD, p, &h.handle, &mount_id, AT_SYMLINK_FOLLOW);
                 if (r < 0)
                         return false;
 
diff --git a/src/shared/util.h b/src/shared/util.h
index 47a3dc9114..a1738856bc 100644
--- a/src/shared/util.h
+++ b/src/shared/util.h
@@ -22,6 +22,7 @@
 ***/
 
 #include <alloca.h>
+#include <fcntl.h>
 #include <inttypes.h>
 #include <time.h>
 #include <sys/time.h>
@@ -776,3 +777,8 @@ static inline void qsort_safe(void *base, size_t nmemb, size_t size,
                 qsort(base, nmemb, size, compar);
         }
 }
+
+union file_handle_union {
+  struct file_handle handle;
+  char padding[sizeof(struct file_handle) + MAX_HANDLE_SZ];
+};
diff --git a/src/tmpfiles/tmpfiles.c b/src/tmpfiles/tmpfiles.c
index fb88acd7b9..98d01a1384 100644
--- a/src/tmpfiles/tmpfiles.c
+++ b/src/tmpfiles/tmpfiles.c
@@ -215,19 +215,16 @@ static bool unix_socket_alive(const char *fn) {
 }
 
 static int dir_is_mount_point(DIR *d, const char *subdir) {
-        struct file_handle *h;
+        union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ };
         int mount_id_parent, mount_id;
         int r_p, r;
 
-        h = alloca(MAX_HANDLE_SZ);
-
-        h->handle_bytes = MAX_HANDLE_SZ;
-        r_p = name_to_handle_at(dirfd(d), ".", h, &mount_id_parent, 0);
+        r_p = name_to_handle_at(dirfd(d), ".", &h.handle, &mount_id_parent, 0);
         if (r_p < 0)
                 r_p = -errno;
 
-        h->handle_bytes = MAX_HANDLE_SZ;
-        r = name_to_handle_at(dirfd(d), subdir, h, &mount_id, 0);
+        h.handle.handle_bytes = MAX_HANDLE_SZ;
+        r = name_to_handle_at(dirfd(d), subdir, &h.handle, &mount_id, 0);
         if (r < 0)
                 r = -errno;