This is a note to let you know that I've just added the patch titled
dm ioctl: fix alignment of event number in the device list
to the 4.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-ioctl-fix-alignment-of-event-number-in-the-device-list.patch
and it can be found in the queue-4.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 62e082430ea4bb5b28909ca4375bb683931e22aa Mon Sep 17 00:00:00 2001
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Date: Wed, 20 Sep 2017 07:29:49 -0400
Subject: dm ioctl: fix alignment of event number in the device list
From: Mikulas Patocka <mpatocka@xxxxxxxxxx>
commit 62e082430ea4bb5b28909ca4375bb683931e22aa upstream.
The size of struct dm_name_list is different on 32-bit and 64-bit
kernels (so "(nl + 1)" differs between 32-bit and 64-bit kernels).
This mismatch caused some harmless difference in padding when using 32-bit
or 64-bit kernel. Commit 23d70c5e52dd ("dm ioctl: report event number in
DM_LIST_DEVICES") added reporting event number in the output of
DM_LIST_DEVICES_CMD. This difference in padding makes it impossible for
userspace to determine the location of the event number (the location
would be different when running on 32-bit and 64-bit kernels).
Fix the padding by using offsetof(struct dm_name_list, name) instead of
sizeof(struct dm_name_list) to determine the location of entries.
Also, the ioctl version number is incremented to 37 so that userspace
can use the version number to determine that the event number is present
and correctly located.
In addition, a global event is now raised when a DM device is created,
removed, renamed or when table is swapped, so that the user can monitor
for device changes.
Reported-by: Eugene Syromiatnikov <esyr@xxxxxxxxxx>
Fixes: 23d70c5e52dd ("dm ioctl: report event number in DM_LIST_DEVICES")
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/dm-core.h | 1 +
drivers/md/dm-ioctl.c | 37 ++++++++++++++++++++++++-------------
drivers/md/dm.c | 10 ++++++++--
include/uapi/linux/dm-ioctl.h | 4 ++--
4 files changed, 35 insertions(+), 17 deletions(-)
--- a/drivers/md/dm-core.h
+++ b/drivers/md/dm-core.h
@@ -149,5 +149,6 @@ static inline bool dm_message_test_buffe
extern atomic_t dm_global_event_nr;
extern wait_queue_head_t dm_global_eventq;
+void dm_issue_global_event(void);
#endif
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -477,9 +477,13 @@ static int remove_all(struct file *filp,
* Round up the ptr to an 8-byte boundary.
*/
#define ALIGN_MASK 7
+static inline size_t align_val(size_t val)
+{
+ return (val + ALIGN_MASK) & ~ALIGN_MASK;
+}
static inline void *align_ptr(void *ptr)
{
- return (void *) (((size_t) (ptr + ALIGN_MASK)) & ~ALIGN_MASK);
+ return (void *)align_val((size_t)ptr);
}
/*
@@ -505,7 +509,7 @@ static int list_devices(struct file *fil
struct hash_cell *hc;
size_t len, needed = 0;
struct gendisk *disk;
- struct dm_name_list *nl, *old_nl = NULL;
+ struct dm_name_list *orig_nl, *nl, *old_nl = NULL;
uint32_t *event_nr;
down_write(&_hash_lock);
@@ -516,17 +520,15 @@ static int list_devices(struct file *fil
*/
for (i = 0; i < NUM_BUCKETS; i++) {
list_for_each_entry (hc, _name_buckets + i, name_list) {
- needed += sizeof(struct dm_name_list);
- needed += strlen(hc->name) + 1;
- needed += ALIGN_MASK;
- needed += (sizeof(uint32_t) + ALIGN_MASK) & ~ALIGN_MASK;
+ needed += align_val(offsetof(struct dm_name_list, name) + strlen(hc->name) + 1);
+ needed += align_val(sizeof(uint32_t));
}
}
/*
* Grab our output buffer.
*/
- nl = get_result_buffer(param, param_size, &len);
+ nl = orig_nl = get_result_buffer(param, param_size, &len);
if (len < needed) {
param->flags |= DM_BUFFER_FULL_FLAG;
goto out;
@@ -549,11 +551,16 @@ static int list_devices(struct file *fil
strcpy(nl->name, hc->name);
old_nl = nl;
- event_nr = align_ptr(((void *) (nl + 1)) + strlen(hc->name) + 1);
+ event_nr = align_ptr(nl->name + strlen(hc->name) + 1);
*event_nr = dm_get_event_nr(hc->md);
nl = align_ptr(event_nr + 1);
}
}
+ /*
+ * If mismatch happens, security may be compromised due to buffer
+ * overflow, so it's better to crash.
+ */
+ BUG_ON((char *)nl - (char *)orig_nl != needed);
out:
up_write(&_hash_lock);
@@ -1621,7 +1628,8 @@ static int target_message(struct file *f
* which has a variable size, is not used by the function processing
* the ioctl.
*/
-#define IOCTL_FLAGS_NO_PARAMS 1
+#define IOCTL_FLAGS_NO_PARAMS 1
+#define IOCTL_FLAGS_ISSUE_GLOBAL_EVENT 2
/*-----------------------------------------------------------------
* Implementation of open/close/ioctl on the special char
@@ -1635,12 +1643,12 @@ static ioctl_fn lookup_ioctl(unsigned in
ioctl_fn fn;
} _ioctls[] = {
{DM_VERSION_CMD, 0, NULL}, /* version is dealt with elsewhere */
- {DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS, remove_all},
+ {DM_REMOVE_ALL_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, remove_all},
{DM_LIST_DEVICES_CMD, 0, list_devices},
- {DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_create},
- {DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS, dev_remove},
- {DM_DEV_RENAME_CMD, 0, dev_rename},
+ {DM_DEV_CREATE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_create},
+ {DM_DEV_REMOVE_CMD, IOCTL_FLAGS_NO_PARAMS | IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_remove},
+ {DM_DEV_RENAME_CMD, IOCTL_FLAGS_ISSUE_GLOBAL_EVENT, dev_rename},
{DM_DEV_SUSPEND_CMD, IOCTL_FLAGS_NO_PARAMS, dev_suspend},
{DM_DEV_STATUS_CMD, IOCTL_FLAGS_NO_PARAMS, dev_status},
{DM_DEV_WAIT_CMD, 0, dev_wait},
@@ -1869,6 +1877,9 @@ static int ctl_ioctl(struct file *file,
unlikely(ioctl_flags & IOCTL_FLAGS_NO_PARAMS))
DMERR("ioctl %d tried to output some data but has IOCTL_FLAGS_NO_PARAMS set", cmd);
+ if (!r && ioctl_flags & IOCTL_FLAGS_ISSUE_GLOBAL_EVENT)
+ dm_issue_global_event();
+
/*
* Copy the results back to userland.
*/
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -52,6 +52,12 @@ static struct workqueue_struct *deferred
atomic_t dm_global_event_nr = ATOMIC_INIT(0);
DECLARE_WAIT_QUEUE_HEAD(dm_global_eventq);
+void dm_issue_global_event(void)
+{
+ atomic_inc(&dm_global_event_nr);
+ wake_up(&dm_global_eventq);
+}
+
/*
* One of these is allocated per bio.
*/
@@ -1865,9 +1871,8 @@ static void event_callback(void *context
dm_send_uevents(&uevents, &disk_to_dev(md->disk)->kobj);
atomic_inc(&md->event_nr);
- atomic_inc(&dm_global_event_nr);
wake_up(&md->eventq);
- wake_up(&dm_global_eventq);
+ dm_issue_global_event();
}
/*
@@ -2283,6 +2288,7 @@ struct dm_table *dm_swap_table(struct ma
}
map = __bind(md, table, &limits);
+ dm_issue_global_event();
out:
mutex_unlock(&md->suspend_lock);
--- a/include/uapi/linux/dm-ioctl.h
+++ b/include/uapi/linux/dm-ioctl.h
@@ -269,9 +269,9 @@ enum {
#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
#define DM_VERSION_MAJOR 4
-#define DM_VERSION_MINOR 36
+#define DM_VERSION_MINOR 37
#define DM_VERSION_PATCHLEVEL 0
-#define DM_VERSION_EXTRA "-ioctl (2017-06-09)"
+#define DM_VERSION_EXTRA "-ioctl (2017-09-20)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */
Patches currently in stable-queue which might be from mpatocka@xxxxxxxxxx are
queue-4.13/dm-ioctl-fix-alignment-of-event-number-in-the-device-list.patch