Messages in this thread Patch in this message | | | From | Chao Yu <> | Subject | [PATCH v2 3/4] f2fs: fix NULL pointer dereference in f2fs_verity_work() | Date | Sat, 21 Mar 2020 20:21:53 +0800 |
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From: Chao Yu <yuchao0@huawei.com>
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> --- v2: - fix error path of f2fs_verify_bio pointed out by Eric fs/f2fs/data.c | 37 ++++++++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-)
diff --git a/fs/f2fs/data.c b/fs/f2fs/data.c index 5c5db09324b7..d5b1eda21519 100644 --- a/fs/f2fs/data.c +++ b/fs/f2fs/data.c @@ -187,12 +187,39 @@ 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; + struct decompress_io_ctx *dic, *pdic = NULL; + + bio_for_each_segment_all(bv, bio, iter_all) { + struct page *page = bv->bv_page; + + dic = (struct decompress_io_ctx *)page_private(page); - f2fs_verify_pages(dic->rpages, dic->cluster_size); - f2fs_free_dic(dic); + if (dic) { + if (dic != pdic) { + f2fs_verify_pages(dic->rpages, + dic->cluster_size); + f2fs_free_dic(dic); + pdic = dic; + } + continue; + } + pdic = dic; + + 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 -- 2.22.0
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