linux-kernel - [PATCH v4] f2fs: avoid out-of-range memory access

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Message-Id: <20190708043456.24935-1-oceanchen@google.com>
Date:   Mon,  8 Jul 2019 12:34:56 +0800
From:   Ocean Chen <oceanchen@...gle.com>
To:     jaegeuk@...nel.org, yuchao0@...wei.com,
        linux-f2fs-devel@...ts.sourceforge.net,
        linux-kernel@...r.kernel.org
Cc:     oceanchen@...gle.com
Subject: [PATCH v4] f2fs: avoid out-of-range memory access

blkoff_off might over 512 due to fs corrupt or security
vulnerability. That should be checked before being using.

Use ENTRIES_IN_SUM to protect invalid value in cur_data_blkoff.

Signed-off-by: Ocean Chen <oceanchen@...gle.com>
---
 fs/f2fs/segment.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c
index 8dee063c833f..ac824f6632b6 100644
--- a/fs/f2fs/segment.c
+++ b/fs/f2fs/segment.c
@@ -3393,6 +3393,11 @@ static int read_compacted_summaries(struct f2fs_sb_info *sbi)
 		seg_i = CURSEG_I(sbi, i);
 		segno = le32_to_cpu(ckpt->cur_data_segno[i]);
 		blk_off = le16_to_cpu(ckpt->cur_data_blkoff[i]);
+		if (blk_off > ENTRIES_IN_SUM) {
+			f2fs_bug_on(sbi, 1);
+			f2fs_put_page(page, 1);
+			return -EFAULT;
+		}
 		seg_i->next_segno = segno;
 		reset_curseg(sbi, i, 0);
 		seg_i->alloc_type = ckpt->alloc_type[i];
-- 
2.22.0.410.gd8fdbe21b5-goog