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f2fs: fix NULL pointer dereference in f2fs_verity_work()

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If both compression and fsverity feature is on, generic/572 will
report below NULL pointer dereference bug.

 BUG: kernel NULL pointer dereference, address: 0000000000000018
 RIP: 0010:f2fs_verity_work+0x60/0x90 [f2fs]
 #PF: supervisor read access in kernel mode
 Workqueue: fsverity_read_queue f2fs_verity_work [f2fs]
 RIP: 0010:f2fs_verity_work+0x60/0x90 [f2fs]
 Call Trace:
  process_one_work+0x16c/0x3f0
  worker_thread+0x4c/0x440
  ? rescuer_thread+0x350/0x350
  kthread+0xf8/0x130
  ? kthread_unpark+0x70/0x70
  ret_from_fork+0x35/0x40

There are two issue in f2fs_verity_work():
- it needs to traverse and verify all pages in bio.
- if pages in bio belong to non-compressed cluster, accessing
decompress IO context stored in page private will cause NULL
pointer dereference.

Fix them.

Signed-off-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Chao Yu 2020-03-23 17:43:04 +08:00 committed by Jaegeuk Kim
parent 23c51bed6f
commit 79bbefb19f
2 changed files with 32 additions and 5 deletions
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2
fs/f2fs/compress.c
View File

@ -477,6 +477,8 @@ out_vunmap_cbuf:
out_vunmap_rbuf:
vunmap(dic->rbuf);
out_free_dic:
if (verity)
refcount_add(dic->nr_cpages - 1, &dic->ref);
if (!verity)
f2fs_decompress_end_io(dic->rpages, dic->cluster_size,
ret, false);

35
fs/f2fs/data.c
View File

@ -187,12 +187,37 @@ static void f2fs_verify_pages(struct page **rpages, unsigned int cluster_size)
static void f2fs_verify_bio(struct bio *bio)
{
struct page *page = bio_first_page_all(bio);
struct decompress_io_ctx *dic =
(struct decompress_io_ctx *)page_private(page);
struct bio_vec *bv;
struct bvec_iter_all iter_all;
f2fs_verify_pages(dic->rpages, dic->cluster_size);
f2fs_free_dic(dic);
bio_for_each_segment_all(bv, bio, iter_all) {
struct page *page = bv->bv_page;
struct decompress_io_ctx *dic;
dic = (struct decompress_io_ctx *)page_private(page);
if (dic) {
if (refcount_dec_not_one(&dic->ref))
continue;
f2fs_verify_pages(dic->rpages,
dic->cluster_size);
f2fs_free_dic(dic);
continue;
}
if (bio->bi_status || PageError(page))
goto clear_uptodate;
if (fsverity_verify_page(page)) {
SetPageUptodate(page);
goto unlock;
}
clear_uptodate:
ClearPageUptodate(page);
ClearPageError(page);
unlock:
unlock_page(page);
}
}
#endif