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f2fs: fix use-after-free of dicard command entry 

As Dan Carpenter reported:

The patch 20ee4382322c: "f2fs: issue small discard by LBA order" from
Jul 8, 2018, leads to the following Smatch warning:

	fs/f2fs/segment.c:1277 __issue_discard_cmd_orderly()
	warn: 'dc' was already freed.

See also:
fs/f2fs/segment.c:2550 __issue_discard_cmd_range() warn: 'dc' was already freed.

In order to fix this issue, let's get error from __submit_discard_cmd(),
and release current discard command after we referenced next one.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2018-08-08 10:14:55 +08:00 committed by Jaegeuk Kim
parent b83dcfe671
commit 6b9cb1242c
1 changed files with 48 additions and 37 deletions
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85
fs/f2fs/segment.c
View File

@ -994,7 +994,7 @@ static void __update_discard_tree_range(struct f2fs_sb_info *sbi,
struct block_device *bdev, block_t lstart,
block_t start, block_t len);
/* this function is copied from blkdev_issue_discard from block/blk-lib.c */
static void __submit_discard_cmd(struct f2fs_sb_info *sbi,
static int __submit_discard_cmd(struct f2fs_sb_info *sbi,
struct discard_policy *dpolicy,
struct discard_cmd *dc,
unsigned int *issued)
@ -1011,10 +1011,10 @@ static void __submit_discard_cmd(struct f2fs_sb_info *sbi,
int err = 0;
if (dc->state != D_PREP)
return;
return 0;
if (is_sbi_flag_set(sbi, SBI_NEED_FSCK))
return;
return 0;
trace_f2fs_issue_discard(bdev, dc->start, dc->len);
@ -1053,52 +1053,54 @@ static void __submit_discard_cmd(struct f2fs_sb_info *sbi,
SECTOR_FROM_BLOCK(len),
GFP_NOFS, 0, &bio);
submit:
if (!err && bio) {
/*
* should keep before submission to avoid D_DONE
* right away
*/
spin_lock_irqsave(&dc->lock, flags);
if (last)
dc->state = D_SUBMIT;
else
dc->state = D_PARTIAL;
dc->bio_ref++;
spin_unlock_irqrestore(&dc->lock, flags);
atomic_inc(&dcc->issing_discard);
dc->issuing++;
list_move_tail(&dc->list, wait_list);
/* sanity check on discard range */
__check_sit_bitmap(sbi, start, start + len);
bio->bi_private = dc;
bio->bi_end_io = f2fs_submit_discard_endio;
bio->bi_opf |= flag;
submit_bio(bio);
atomic_inc(&dcc->issued_discard);
f2fs_update_iostat(sbi, FS_DISCARD, 1);
} else {
if (err) {
spin_lock_irqsave(&dc->lock, flags);
if (dc->state == D_PARTIAL)
dc->state = D_SUBMIT;
spin_unlock_irqrestore(&dc->lock, flags);
__remove_discard_cmd(sbi, dc);
err = -EIO;
break;
}
f2fs_bug_on(sbi, !bio);
/*
* should keep before submission to avoid D_DONE
* right away
*/
spin_lock_irqsave(&dc->lock, flags);
if (last)
dc->state = D_SUBMIT;
else
dc->state = D_PARTIAL;
dc->bio_ref++;
spin_unlock_irqrestore(&dc->lock, flags);
atomic_inc(&dcc->issing_discard);
dc->issuing++;
list_move_tail(&dc->list, wait_list);
/* sanity check on discard range */
__check_sit_bitmap(sbi, start, start + len);
bio->bi_private = dc;
bio->bi_end_io = f2fs_submit_discard_endio;
bio->bi_opf |= flag;
submit_bio(bio);
atomic_inc(&dcc->issued_discard);
f2fs_update_iostat(sbi, FS_DISCARD, 1);
lstart += len;
start += len;
total_len -= len;
len = total_len;
}
if (len)
if (!err && len)
__update_discard_tree_range(sbi, bdev, lstart, start, len);
return err;
}
static struct discard_cmd *__insert_discard_tree(struct f2fs_sb_info *sbi,
@ -1304,6 +1306,7 @@ static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
while (dc) {
struct rb_node *node;
int err = 0;
if (dc->state != D_PREP)
goto next;
@ -1314,12 +1317,14 @@ static unsigned int __issue_discard_cmd_orderly(struct f2fs_sb_info *sbi,
}
dcc->next_pos = dc->lstart + dc->len;
__submit_discard_cmd(sbi, dpolicy, dc, &issued);
err = __submit_discard_cmd(sbi, dpolicy, dc, &issued);
if (issued >= dpolicy->max_requests)
break;
next:
node = rb_next(&dc->rb_node);
if (err)
__remove_discard_cmd(sbi, dc);
dc = rb_entry_safe(node, struct discard_cmd, rb_node);
}
@ -2571,6 +2576,7 @@ static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
while (dc && dc->lstart <= end) {
struct rb_node *node;
int err = 0;
if (dc->len < dpolicy->granularity)
goto skip;
@ -2580,11 +2586,14 @@ static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
goto skip;
}
__submit_discard_cmd(sbi, dpolicy, dc, &issued);
err = __submit_discard_cmd(sbi, dpolicy, dc, &issued);
if (issued >= dpolicy->max_requests) {
start = dc->lstart + dc->len;
if (err)
__remove_discard_cmd(sbi, dc);
blk_finish_plug(&plug);
mutex_unlock(&dcc->cmd_lock);
trimmed += __wait_all_discard_cmd(sbi, NULL);
@ -2593,6 +2602,8 @@ static unsigned int __issue_discard_cmd_range(struct f2fs_sb_info *sbi,
}
skip:
node = rb_next(&dc->rb_node);
if (err)
__remove_discard_cmd(sbi, dc);
dc = rb_entry_safe(node, struct discard_cmd, rb_node);
if (fatal_signal_pending(current))