convert DM printk macros to pr_<level> macros & fix printk() rate limiting code & fix race between dm_get_from_kobject() and __dm_destroy() in kernel-dm CVE-2017-18203
Tracked by Jolla
(Rejected)
asked 2018-06-26 07:59:53 +0300
This post is a wiki. Anyone with karma >75 is welcome to improve it.
The dm_get_from_kobject function in drivers/md/dm.c in the Linux kernel before 4.14.3 allow local users to cause a denial of service (BUG) by leveraging a race condition with __dm_destroy during creation and removal of DM devices. CVSS Score: 4.7medium local
The jolla1 has following Kernel-options set, so DM is present: CONFIG_MD=y , CONFIG_BLK_DEV_DM_BUILTIN=y , CONFIG_BLK_DEV_DM=y and CONFIG_DM_CRYPT=y.
Kernel-3.2 patches are available: |1| |2| |3|
Files affected: kernel-adaptation-sbj-3.4.108.20171107.1/drivers/md/dm.c
kernel-adaptation-sbj-3.4.108.20171107.1/include/linux/device-mapper.h
So the whole patch should look like:
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index c00bcdc..ca688a2 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -25,16 +25,6 @@
#define DM_MSG_PREFIX "core"
-#ifdef CONFIG_PRINTK
-/*
- * ratelimit state to be used in DMXXX_LIMIT().
- */
-DEFINE_RATELIMIT_STATE(dm_ratelimit_state,
- DEFAULT_RATELIMIT_INTERVAL,
- DEFAULT_RATELIMIT_BURST);
-EXPORT_SYMBOL(dm_ratelimit_state);
-#endif
-
/*
* Cookies are numeric values sent with CHANGE and REMOVE
* uevents while resuming, removing or renaming the device.
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index ca688a2..d7e6399 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2692,11 +2682,15 @@ struct mapped_device *dm_get_from_kobject(struct kobject *kobj)
md = container_of(kobj, struct mapped_device, kobj_holder.kobj);
- if (test_bit(DMF_FREEING, &md->flags) ||
- dm_deleting_md(md))
- return NULL;
-
+ spin_lock(&_minor_lock);
+ if (test_bit(DMF_FREEING, &md->flags) || dm_deleting_md(md)) {
+ md = NULL;
+ goto out;
+ }
dm_get(md);
+out:
+ spin_unlock(&_minor_lock);
+
return md;
}
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 213a870..e1e1842 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -404,48 +404,41 @@ extern struct ratelimit_state dm_ratelimit_state;
#define dm_ratelimit() 0
#endif
-#define DMCRIT(f, arg...) \
- printk(KERN_CRIT DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
-
-#define DMERR(f, arg...) \
- printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
-#define DMERR_LIMIT(f, arg...) \
- do { \
- if (dm_ratelimit()) \
- printk(KERN_ERR DM_NAME ": " DM_MSG_PREFIX ": " \
- f "\n", ## arg); \
- } while (0)
-
-#define DMWARN(f, arg...) \
- printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
-#define DMWARN_LIMIT(f, arg...) \
- do { \
- if (dm_ratelimit()) \
- printk(KERN_WARNING DM_NAME ": " DM_MSG_PREFIX ": " \
- f "\n", ## arg); \
- } while (0)
-
-#define DMINFO(f, arg...) \
- printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f "\n", ## arg)
-#define DMINFO_LIMIT(f, arg...) \
- do { \
- if (dm_ratelimit()) \
- printk(KERN_INFO DM_NAME ": " DM_MSG_PREFIX ": " f \
- "\n", ## arg); \
- } while (0)
+#define DM_FMT(fmt) DM_NAME ": " DM_MSG_PREFIX ": " fmt "\n"
+
+#define DMCRIT(fmt, ...) pr_crit(DM_FMT(fmt), ##__VA_ARGS__)
+
+#define DMERR(fmt, ...) pr_err(DM_FMT(fmt), ##__VA_ARGS__)
+#define DMERR_LIMIT(fmt, ...) \
+do { \
+ if (dm_ratelimit()) \
+ DMERR(fmt, ##__VA_ARGS__); \
+} while (0)
+
+#define DMWARN(fmt, ...) pr_warn(DM_FMT(fmt), ##__VA_ARGS__)
+#define DMWARN_LIMIT(fmt, ...) \
+do { \
+ if (dm_ratelimit()) \
+ DMWARN(fmt, ##__VA_ARGS__); \
+} while (0)
+
+#define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
+#define DMINFO_LIMIT(fmt, ...) \
+do { \
+ if (dm_ratelimit()) \
+ DMINFO(fmt, ##__VA_ARGS__); \
+} while (0)
#ifdef CONFIG_DM_DEBUG
-# define DMDEBUG(f, arg...) \
- printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX " DEBUG: " f "\n", ## arg)
-# define DMDEBUG_LIMIT(f, arg...) \
- do { \
- if (dm_ratelimit()) \
- printk(KERN_DEBUG DM_NAME ": " DM_MSG_PREFIX ": " f \
- "\n", ## arg); \
- } while (0)
+#define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__)
+#define DMDEBUG_LIMIT(fmt, ...) \
+do { \
+ if (dm_ratelimit()) \
+ DMDEBUG(fmt, ##__VA_ARGS__); \
+} while (0)
#else
-# define DMDEBUG(f, arg...) do {} while (0)
-# define DMDEBUG_LIMIT(f, arg...) do {} while (0)
+#define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
+#define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
#endif
#define DMEMIT(x...) sz += ((sz >= maxlen) ? \
and as a second step, finally:
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index e1e1842..45bf2dd 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -396,46 xxxxx @@ void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
*---------------------------------------------------------------*/
#define DM_NAME "device-mapper"
-#ifdef CONFIG_PRINTK
-extern struct ratelimit_state dm_ratelimit_state;
-
-#define dm_ratelimit() __ratelimit(&dm_ratelimit_state)
-#else
-#define dm_ratelimit() 0
-#endif
+#define DM_RATELIMIT(pr_func, fmt, ...) \
+do { \
+ static DEFINE_RATELIMIT_STATE(rs, DEFAULT_RATELIMIT_INTERVAL, \
+ DEFAULT_RATELIMIT_BURST); \
+ \
+ if (__ratelimit(&rs)) \
+ pr_func(DM_FMT(fmt), ##__VA_ARGS__); \
+} while (0)
#define DM_FMT(fmt) DM_NAME ": " DM_MSG_PREFIX ": " fmt "\n"
#define DMCRIT(fmt, ...) pr_crit(DM_FMT(fmt), ##__VA_ARGS__)
#define DMERR(fmt, ...) pr_err(DM_FMT(fmt), ##__VA_ARGS__)
-#define DMERR_LIMIT(fmt, ...) \
-do { \
- if (dm_ratelimit()) \
- DMERR(fmt, ##__VA_ARGS__); \
-} while (0)
-
+#define DMERR_LIMIT(fmt, ...) DM_RATELIMIT(pr_err, fmt, ##__VA_ARGS__)
#define DMWARN(fmt, ...) pr_warn(DM_FMT(fmt), ##__VA_ARGS__)
-#define DMWARN_LIMIT(fmt, ...) \
-do { \
- if (dm_ratelimit()) \
- DMWARN(fmt, ##__VA_ARGS__); \
-} while (0)
-
+#define DMWARN_LIMIT(fmt, ...) DM_RATELIMIT(pr_warn, fmt, ##__VA_ARGS__)
#define DMINFO(fmt, ...) pr_info(DM_FMT(fmt), ##__VA_ARGS__)
-#define DMINFO_LIMIT(fmt, ...) \
-do { \
- if (dm_ratelimit()) \
- DMINFO(fmt, ##__VA_ARGS__); \
-} while (0)
+#define DMINFO_LIMIT(fmt, ...) DM_RATELIMIT(pr_info, fmt, ##__VA_ARGS__)
#ifdef CONFIG_DM_DEBUG
#define DMDEBUG(fmt, ...) printk(KERN_DEBUG DM_FMT(fmt), ##__VA_ARGS__)
-#define DMDEBUG_LIMIT(fmt, ...) \
-do { \
- if (dm_ratelimit()) \
- DMDEBUG(fmt, ##__VA_ARGS__); \
-} while (0)
+#define DMDEBUG_LIMIT(fmt, ...) DM_RATELIMIT(pr_debug, fmt, ##__VA_ARGS__)
#else
#define DMDEBUG(fmt, ...) no_printk(fmt, ##__VA_ARGS__)
#define DMDEBUG_LIMIT(fmt, ...) no_printk(fmt, ##__VA_ARGS__)