From 370c860f748d149097710dc7952a64f627db9de7 Mon Sep 17 00:00:00 2001 From: Dave Reisner Date: Sat, 19 Apr 2014 13:22:35 -0400 Subject: 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. --- src/libudev/libudev-monitor.c | 6 ++---- src/readahead/readahead-common.c | 6 ++---- src/shared/util.h | 6 ++++++ src/tmpfiles/tmpfiles.c | 11 ++++------- 4 files changed, 14 insertions(+), 15 deletions(-) diff --git a/src/libudev/libudev-monitor.c b/src/libudev/libudev-monitor.c index 3f7436b09..0a2ab82a8 100644 --- a/src/libudev/libudev-monitor.c +++ b/src/libudev/libudev-monitor.c @@ -108,15 +108,13 @@ static struct udev_monitor *udev_monitor_new(struct udev *udev) /* we consider udev running when /dev is on devtmpfs */ static bool udev_has_devtmpfs(struct udev *udev) { - struct file_handle *h; + union file_handle_union h = { .handle.handle_bytes = MAX_HANDLE_SZ, }; int mount_id; _cleanup_fclose_ FILE *f = NULL; char line[LINE_MAX], *e; int r; - h = alloca(MAX_HANDLE_SZ); - h->handle_bytes = MAX_HANDLE_SZ; - r = name_to_handle_at(AT_FDCWD, "/dev", h, &mount_id, 0); + r = name_to_handle_at(AT_FDCWD, "/dev", &h.handle, &mount_id, 0); if (r < 0) return false; diff --git a/src/readahead/readahead-common.c b/src/readahead/readahead-common.c index 5ffa88b78..49679fc83 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 900f1cf54..891848a1d 100644 --- a/src/shared/util.h +++ b/src/shared/util.h @@ -22,6 +22,7 @@ ***/ #include +#include #include #include #include @@ -914,3 +915,8 @@ uint64_t physical_memory(void); char* mount_test_option(const char *haystack, const char *needle); void hexdump(FILE *f, const void *p, size_t s); + +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 33e7cbc05..04b472da9 100644 --- a/src/tmpfiles/tmpfiles.c +++ b/src/tmpfiles/tmpfiles.c @@ -217,19 +217,16 @@ 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; -- cgit v1.2.3