Revision 73223e4e2e3867ebf033a5a8eb2e5df0158ccc99 authored by zhong jiang on 18 August 2017, 22:16:24 UTC, committed by Linus Torvalds on 18 August 2017, 22:32:02 UTC
I hit a use after free issue when executing trinity and repoduced it with KASAN enabled. The related call trace is as follows. BUG: KASan: use after free in SyS_get_mempolicy+0x3c8/0x960 at addr ffff8801f582d766 Read of size 2 by task syz-executor1/798 INFO: Allocated in mpol_new.part.2+0x74/0x160 age=3 cpu=1 pid=799 __slab_alloc+0x768/0x970 kmem_cache_alloc+0x2e7/0x450 mpol_new.part.2+0x74/0x160 mpol_new+0x66/0x80 SyS_mbind+0x267/0x9f0 system_call_fastpath+0x16/0x1b INFO: Freed in __mpol_put+0x2b/0x40 age=4 cpu=1 pid=799 __slab_free+0x495/0x8e0 kmem_cache_free+0x2f3/0x4c0 __mpol_put+0x2b/0x40 SyS_mbind+0x383/0x9f0 system_call_fastpath+0x16/0x1b INFO: Slab 0xffffea0009cb8dc0 objects=23 used=8 fp=0xffff8801f582de40 flags=0x200000000004080 INFO: Object 0xffff8801f582d760 @offset=5984 fp=0xffff8801f582d600 Bytes b4 ffff8801f582d750: ae 01 ff ff 00 00 00 00 5a 5a 5a 5a 5a 5a 5a 5a ........ZZZZZZZZ Object ffff8801f582d760: 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b kkkkkkkkkkkkkkkk Object ffff8801f582d770: 6b 6b 6b 6b 6b 6b 6b a5 kkkkkkk. Redzone ffff8801f582d778: bb bb bb bb bb bb bb bb ........ Padding ffff8801f582d8b8: 5a 5a 5a 5a 5a 5a 5a 5a ZZZZZZZZ Memory state around the buggy address: ffff8801f582d600: fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8801f582d680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8801f582d700: fc fc fc fc fc fc fc fc fc fc fc fc fb fb fb fc !shared memory policy is not protected against parallel removal by other thread which is normally protected by the mmap_sem. do_get_mempolicy, however, drops the lock midway while we can still access it later. Early premature up_read is a historical artifact from times when put_user was called in this path see https://lwn.net/Articles/124754/ but that is gone since 8bccd85ffbaf ("[PATCH] Implement sys_* do_* layering in the memory policy layer."). but when we have the the current mempolicy ref count model. The issue was introduced accordingly. Fix the issue by removing the premature release. Link: http://lkml.kernel.org/r/1502950924-27521-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhong jiang <zhongjiang@huawei.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Rientjes <rientjes@google.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: <stable@vger.kernel.org> [2.6+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent da094e4
mq-deadline.c
/*
* MQ Deadline i/o scheduler - adaptation of the legacy deadline scheduler,
* for the blk-mq scheduling framework
*
* Copyright (C) 2016 Jens Axboe <axboe@kernel.dk>
*/
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/blkdev.h>
#include <linux/blk-mq.h>
#include <linux/elevator.h>
#include <linux/bio.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/rbtree.h>
#include <linux/sbitmap.h>
#include "blk.h"
#include "blk-mq.h"
#include "blk-mq-debugfs.h"
#include "blk-mq-tag.h"
#include "blk-mq-sched.h"
/*
* See Documentation/block/deadline-iosched.txt
*/
static const int read_expire = HZ / 2; /* max time before a read is submitted. */
static const int write_expire = 5 * HZ; /* ditto for writes, these limits are SOFT! */
static const int writes_starved = 2; /* max times reads can starve a write */
static const int fifo_batch = 16; /* # of sequential requests treated as one
by the above parameters. For throughput. */
struct deadline_data {
/*
* run time data
*/
/*
* requests (deadline_rq s) are present on both sort_list and fifo_list
*/
struct rb_root sort_list[2];
struct list_head fifo_list[2];
/*
* next in sort order. read, write or both are NULL
*/
struct request *next_rq[2];
unsigned int batching; /* number of sequential requests made */
unsigned int starved; /* times reads have starved writes */
/*
* settings that change how the i/o scheduler behaves
*/
int fifo_expire[2];
int fifo_batch;
int writes_starved;
int front_merges;
spinlock_t lock;
struct list_head dispatch;
};
static inline struct rb_root *
deadline_rb_root(struct deadline_data *dd, struct request *rq)
{
return &dd->sort_list[rq_data_dir(rq)];
}
/*
* get the request after `rq' in sector-sorted order
*/
static inline struct request *
deadline_latter_request(struct request *rq)
{
struct rb_node *node = rb_next(&rq->rb_node);
if (node)
return rb_entry_rq(node);
return NULL;
}
static void
deadline_add_rq_rb(struct deadline_data *dd, struct request *rq)
{
struct rb_root *root = deadline_rb_root(dd, rq);
elv_rb_add(root, rq);
}
static inline void
deadline_del_rq_rb(struct deadline_data *dd, struct request *rq)
{
const int data_dir = rq_data_dir(rq);
if (dd->next_rq[data_dir] == rq)
dd->next_rq[data_dir] = deadline_latter_request(rq);
elv_rb_del(deadline_rb_root(dd, rq), rq);
}
/*
* remove rq from rbtree and fifo.
*/
static void deadline_remove_request(struct request_queue *q, struct request *rq)
{
struct deadline_data *dd = q->elevator->elevator_data;
list_del_init(&rq->queuelist);
/*
* We might not be on the rbtree, if we are doing an insert merge
*/
if (!RB_EMPTY_NODE(&rq->rb_node))
deadline_del_rq_rb(dd, rq);
elv_rqhash_del(q, rq);
if (q->last_merge == rq)
q->last_merge = NULL;
}
static void dd_request_merged(struct request_queue *q, struct request *req,
enum elv_merge type)
{
struct deadline_data *dd = q->elevator->elevator_data;
/*
* if the merge was a front merge, we need to reposition request
*/
if (type == ELEVATOR_FRONT_MERGE) {
elv_rb_del(deadline_rb_root(dd, req), req);
deadline_add_rq_rb(dd, req);
}
}
static void dd_merged_requests(struct request_queue *q, struct request *req,
struct request *next)
{
/*
* if next expires before rq, assign its expire time to rq
* and move into next position (next will be deleted) in fifo
*/
if (!list_empty(&req->queuelist) && !list_empty(&next->queuelist)) {
if (time_before((unsigned long)next->fifo_time,
(unsigned long)req->fifo_time)) {
list_move(&req->queuelist, &next->queuelist);
req->fifo_time = next->fifo_time;
}
}
/*
* kill knowledge of next, this one is a goner
*/
deadline_remove_request(q, next);
}
/*
* move an entry to dispatch queue
*/
static void
deadline_move_request(struct deadline_data *dd, struct request *rq)
{
const int data_dir = rq_data_dir(rq);
dd->next_rq[READ] = NULL;
dd->next_rq[WRITE] = NULL;
dd->next_rq[data_dir] = deadline_latter_request(rq);
/*
* take it off the sort and fifo list
*/
deadline_remove_request(rq->q, rq);
}
/*
* deadline_check_fifo returns 0 if there are no expired requests on the fifo,
* 1 otherwise. Requires !list_empty(&dd->fifo_list[data_dir])
*/
static inline int deadline_check_fifo(struct deadline_data *dd, int ddir)
{
struct request *rq = rq_entry_fifo(dd->fifo_list[ddir].next);
/*
* rq is expired!
*/
if (time_after_eq(jiffies, (unsigned long)rq->fifo_time))
return 1;
return 0;
}
/*
* deadline_dispatch_requests selects the best request according to
* read/write expire, fifo_batch, etc
*/
static struct request *__dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
struct request *rq;
bool reads, writes;
int data_dir;
if (!list_empty(&dd->dispatch)) {
rq = list_first_entry(&dd->dispatch, struct request, queuelist);
list_del_init(&rq->queuelist);
goto done;
}
reads = !list_empty(&dd->fifo_list[READ]);
writes = !list_empty(&dd->fifo_list[WRITE]);
/*
* batches are currently reads XOR writes
*/
if (dd->next_rq[WRITE])
rq = dd->next_rq[WRITE];
else
rq = dd->next_rq[READ];
if (rq && dd->batching < dd->fifo_batch)
/* we have a next request are still entitled to batch */
goto dispatch_request;
/*
* at this point we are not running a batch. select the appropriate
* data direction (read / write)
*/
if (reads) {
BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[READ]));
if (writes && (dd->starved++ >= dd->writes_starved))
goto dispatch_writes;
data_dir = READ;
goto dispatch_find_request;
}
/*
* there are either no reads or writes have been starved
*/
if (writes) {
dispatch_writes:
BUG_ON(RB_EMPTY_ROOT(&dd->sort_list[WRITE]));
dd->starved = 0;
data_dir = WRITE;
goto dispatch_find_request;
}
return NULL;
dispatch_find_request:
/*
* we are not running a batch, find best request for selected data_dir
*/
if (deadline_check_fifo(dd, data_dir) || !dd->next_rq[data_dir]) {
/*
* A deadline has expired, the last request was in the other
* direction, or we have run out of higher-sectored requests.
* Start again from the request with the earliest expiry time.
*/
rq = rq_entry_fifo(dd->fifo_list[data_dir].next);
} else {
/*
* The last req was the same dir and we have a next request in
* sort order. No expired requests so continue on from here.
*/
rq = dd->next_rq[data_dir];
}
dd->batching = 0;
dispatch_request:
/*
* rq is the selected appropriate request.
*/
dd->batching++;
deadline_move_request(dd, rq);
done:
rq->rq_flags |= RQF_STARTED;
return rq;
}
static struct request *dd_dispatch_request(struct blk_mq_hw_ctx *hctx)
{
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
struct request *rq;
spin_lock(&dd->lock);
rq = __dd_dispatch_request(hctx);
spin_unlock(&dd->lock);
return rq;
}
static void dd_exit_queue(struct elevator_queue *e)
{
struct deadline_data *dd = e->elevator_data;
BUG_ON(!list_empty(&dd->fifo_list[READ]));
BUG_ON(!list_empty(&dd->fifo_list[WRITE]));
kfree(dd);
}
/*
* initialize elevator private data (deadline_data).
*/
static int dd_init_queue(struct request_queue *q, struct elevator_type *e)
{
struct deadline_data *dd;
struct elevator_queue *eq;
eq = elevator_alloc(q, e);
if (!eq)
return -ENOMEM;
dd = kzalloc_node(sizeof(*dd), GFP_KERNEL, q->node);
if (!dd) {
kobject_put(&eq->kobj);
return -ENOMEM;
}
eq->elevator_data = dd;
INIT_LIST_HEAD(&dd->fifo_list[READ]);
INIT_LIST_HEAD(&dd->fifo_list[WRITE]);
dd->sort_list[READ] = RB_ROOT;
dd->sort_list[WRITE] = RB_ROOT;
dd->fifo_expire[READ] = read_expire;
dd->fifo_expire[WRITE] = write_expire;
dd->writes_starved = writes_starved;
dd->front_merges = 1;
dd->fifo_batch = fifo_batch;
spin_lock_init(&dd->lock);
INIT_LIST_HEAD(&dd->dispatch);
q->elevator = eq;
return 0;
}
static int dd_request_merge(struct request_queue *q, struct request **rq,
struct bio *bio)
{
struct deadline_data *dd = q->elevator->elevator_data;
sector_t sector = bio_end_sector(bio);
struct request *__rq;
if (!dd->front_merges)
return ELEVATOR_NO_MERGE;
__rq = elv_rb_find(&dd->sort_list[bio_data_dir(bio)], sector);
if (__rq) {
BUG_ON(sector != blk_rq_pos(__rq));
if (elv_bio_merge_ok(__rq, bio)) {
*rq = __rq;
return ELEVATOR_FRONT_MERGE;
}
}
return ELEVATOR_NO_MERGE;
}
static bool dd_bio_merge(struct blk_mq_hw_ctx *hctx, struct bio *bio)
{
struct request_queue *q = hctx->queue;
struct deadline_data *dd = q->elevator->elevator_data;
struct request *free = NULL;
bool ret;
spin_lock(&dd->lock);
ret = blk_mq_sched_try_merge(q, bio, &free);
spin_unlock(&dd->lock);
if (free)
blk_mq_free_request(free);
return ret;
}
/*
* add rq to rbtree and fifo
*/
static void dd_insert_request(struct blk_mq_hw_ctx *hctx, struct request *rq,
bool at_head)
{
struct request_queue *q = hctx->queue;
struct deadline_data *dd = q->elevator->elevator_data;
const int data_dir = rq_data_dir(rq);
if (blk_mq_sched_try_insert_merge(q, rq))
return;
blk_mq_sched_request_inserted(rq);
if (at_head || blk_rq_is_passthrough(rq)) {
if (at_head)
list_add(&rq->queuelist, &dd->dispatch);
else
list_add_tail(&rq->queuelist, &dd->dispatch);
} else {
deadline_add_rq_rb(dd, rq);
if (rq_mergeable(rq)) {
elv_rqhash_add(q, rq);
if (!q->last_merge)
q->last_merge = rq;
}
/*
* set expire time and add to fifo list
*/
rq->fifo_time = jiffies + dd->fifo_expire[data_dir];
list_add_tail(&rq->queuelist, &dd->fifo_list[data_dir]);
}
}
static void dd_insert_requests(struct blk_mq_hw_ctx *hctx,
struct list_head *list, bool at_head)
{
struct request_queue *q = hctx->queue;
struct deadline_data *dd = q->elevator->elevator_data;
spin_lock(&dd->lock);
while (!list_empty(list)) {
struct request *rq;
rq = list_first_entry(list, struct request, queuelist);
list_del_init(&rq->queuelist);
dd_insert_request(hctx, rq, at_head);
}
spin_unlock(&dd->lock);
}
static bool dd_has_work(struct blk_mq_hw_ctx *hctx)
{
struct deadline_data *dd = hctx->queue->elevator->elevator_data;
return !list_empty_careful(&dd->dispatch) ||
!list_empty_careful(&dd->fifo_list[0]) ||
!list_empty_careful(&dd->fifo_list[1]);
}
/*
* sysfs parts below
*/
static ssize_t
deadline_var_show(int var, char *page)
{
return sprintf(page, "%d\n", var);
}
static ssize_t
deadline_var_store(int *var, const char *page, size_t count)
{
char *p = (char *) page;
*var = simple_strtol(p, &p, 10);
return count;
}
#define SHOW_FUNCTION(__FUNC, __VAR, __CONV) \
static ssize_t __FUNC(struct elevator_queue *e, char *page) \
{ \
struct deadline_data *dd = e->elevator_data; \
int __data = __VAR; \
if (__CONV) \
__data = jiffies_to_msecs(__data); \
return deadline_var_show(__data, (page)); \
}
SHOW_FUNCTION(deadline_read_expire_show, dd->fifo_expire[READ], 1);
SHOW_FUNCTION(deadline_write_expire_show, dd->fifo_expire[WRITE], 1);
SHOW_FUNCTION(deadline_writes_starved_show, dd->writes_starved, 0);
SHOW_FUNCTION(deadline_front_merges_show, dd->front_merges, 0);
SHOW_FUNCTION(deadline_fifo_batch_show, dd->fifo_batch, 0);
#undef SHOW_FUNCTION
#define STORE_FUNCTION(__FUNC, __PTR, MIN, MAX, __CONV) \
static ssize_t __FUNC(struct elevator_queue *e, const char *page, size_t count) \
{ \
struct deadline_data *dd = e->elevator_data; \
int __data; \
int ret = deadline_var_store(&__data, (page), count); \
if (__data < (MIN)) \
__data = (MIN); \
else if (__data > (MAX)) \
__data = (MAX); \
if (__CONV) \
*(__PTR) = msecs_to_jiffies(__data); \
else \
*(__PTR) = __data; \
return ret; \
}
STORE_FUNCTION(deadline_read_expire_store, &dd->fifo_expire[READ], 0, INT_MAX, 1);
STORE_FUNCTION(deadline_write_expire_store, &dd->fifo_expire[WRITE], 0, INT_MAX, 1);
STORE_FUNCTION(deadline_writes_starved_store, &dd->writes_starved, INT_MIN, INT_MAX, 0);
STORE_FUNCTION(deadline_front_merges_store, &dd->front_merges, 0, 1, 0);
STORE_FUNCTION(deadline_fifo_batch_store, &dd->fifo_batch, 0, INT_MAX, 0);
#undef STORE_FUNCTION
#define DD_ATTR(name) \
__ATTR(name, S_IRUGO|S_IWUSR, deadline_##name##_show, \
deadline_##name##_store)
static struct elv_fs_entry deadline_attrs[] = {
DD_ATTR(read_expire),
DD_ATTR(write_expire),
DD_ATTR(writes_starved),
DD_ATTR(front_merges),
DD_ATTR(fifo_batch),
__ATTR_NULL
};
#ifdef CONFIG_BLK_DEBUG_FS
#define DEADLINE_DEBUGFS_DDIR_ATTRS(ddir, name) \
static void *deadline_##name##_fifo_start(struct seq_file *m, \
loff_t *pos) \
__acquires(&dd->lock) \
{ \
struct request_queue *q = m->private; \
struct deadline_data *dd = q->elevator->elevator_data; \
\
spin_lock(&dd->lock); \
return seq_list_start(&dd->fifo_list[ddir], *pos); \
} \
\
static void *deadline_##name##_fifo_next(struct seq_file *m, void *v, \
loff_t *pos) \
{ \
struct request_queue *q = m->private; \
struct deadline_data *dd = q->elevator->elevator_data; \
\
return seq_list_next(v, &dd->fifo_list[ddir], pos); \
} \
\
static void deadline_##name##_fifo_stop(struct seq_file *m, void *v) \
__releases(&dd->lock) \
{ \
struct request_queue *q = m->private; \
struct deadline_data *dd = q->elevator->elevator_data; \
\
spin_unlock(&dd->lock); \
} \
\
static const struct seq_operations deadline_##name##_fifo_seq_ops = { \
.start = deadline_##name##_fifo_start, \
.next = deadline_##name##_fifo_next, \
.stop = deadline_##name##_fifo_stop, \
.show = blk_mq_debugfs_rq_show, \
}; \
\
static int deadline_##name##_next_rq_show(void *data, \
struct seq_file *m) \
{ \
struct request_queue *q = data; \
struct deadline_data *dd = q->elevator->elevator_data; \
struct request *rq = dd->next_rq[ddir]; \
\
if (rq) \
__blk_mq_debugfs_rq_show(m, rq); \
return 0; \
}
DEADLINE_DEBUGFS_DDIR_ATTRS(READ, read)
DEADLINE_DEBUGFS_DDIR_ATTRS(WRITE, write)
#undef DEADLINE_DEBUGFS_DDIR_ATTRS
static int deadline_batching_show(void *data, struct seq_file *m)
{
struct request_queue *q = data;
struct deadline_data *dd = q->elevator->elevator_data;
seq_printf(m, "%u\n", dd->batching);
return 0;
}
static int deadline_starved_show(void *data, struct seq_file *m)
{
struct request_queue *q = data;
struct deadline_data *dd = q->elevator->elevator_data;
seq_printf(m, "%u\n", dd->starved);
return 0;
}
static void *deadline_dispatch_start(struct seq_file *m, loff_t *pos)
__acquires(&dd->lock)
{
struct request_queue *q = m->private;
struct deadline_data *dd = q->elevator->elevator_data;
spin_lock(&dd->lock);
return seq_list_start(&dd->dispatch, *pos);
}
static void *deadline_dispatch_next(struct seq_file *m, void *v, loff_t *pos)
{
struct request_queue *q = m->private;
struct deadline_data *dd = q->elevator->elevator_data;
return seq_list_next(v, &dd->dispatch, pos);
}
static void deadline_dispatch_stop(struct seq_file *m, void *v)
__releases(&dd->lock)
{
struct request_queue *q = m->private;
struct deadline_data *dd = q->elevator->elevator_data;
spin_unlock(&dd->lock);
}
static const struct seq_operations deadline_dispatch_seq_ops = {
.start = deadline_dispatch_start,
.next = deadline_dispatch_next,
.stop = deadline_dispatch_stop,
.show = blk_mq_debugfs_rq_show,
};
#define DEADLINE_QUEUE_DDIR_ATTRS(name) \
{#name "_fifo_list", 0400, .seq_ops = &deadline_##name##_fifo_seq_ops}, \
{#name "_next_rq", 0400, deadline_##name##_next_rq_show}
static const struct blk_mq_debugfs_attr deadline_queue_debugfs_attrs[] = {
DEADLINE_QUEUE_DDIR_ATTRS(read),
DEADLINE_QUEUE_DDIR_ATTRS(write),
{"batching", 0400, deadline_batching_show},
{"starved", 0400, deadline_starved_show},
{"dispatch", 0400, .seq_ops = &deadline_dispatch_seq_ops},
{},
};
#undef DEADLINE_QUEUE_DDIR_ATTRS
#endif
static struct elevator_type mq_deadline = {
.ops.mq = {
.insert_requests = dd_insert_requests,
.dispatch_request = dd_dispatch_request,
.next_request = elv_rb_latter_request,
.former_request = elv_rb_former_request,
.bio_merge = dd_bio_merge,
.request_merge = dd_request_merge,
.requests_merged = dd_merged_requests,
.request_merged = dd_request_merged,
.has_work = dd_has_work,
.init_sched = dd_init_queue,
.exit_sched = dd_exit_queue,
},
.uses_mq = true,
#ifdef CONFIG_BLK_DEBUG_FS
.queue_debugfs_attrs = deadline_queue_debugfs_attrs,
#endif
.elevator_attrs = deadline_attrs,
.elevator_name = "mq-deadline",
.elevator_owner = THIS_MODULE,
};
static int __init deadline_init(void)
{
return elv_register(&mq_deadline);
}
static void __exit deadline_exit(void)
{
elv_unregister(&mq_deadline);
}
module_init(deadline_init);
module_exit(deadline_exit);
MODULE_AUTHOR("Jens Axboe");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("MQ deadline IO scheduler");
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