linux-kernel - [PATCH RFC 2/5] Revert "ubifs: Fix out-of-bounds memory access caused by abnormal value of node

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Date:   Tue, 16 Jun 2020 15:11:43 +0800
From:   Zhihao Cheng <chengzhihao1@...wei.com>
To:     <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
CC:     <richard@....at>, <yi.zhang@...wei.com>, <liu.song11@....com.cn>
Subject: [PATCH RFC 2/5] Revert "ubifs: Fix out-of-bounds memory access caused by abnormal value of node_len"

This reverts commit acc5af3efa303d5f36cc8c0f61716161f6ca1384.

No need to avoid memory oob in dumping for data node alone. Later, node
length will be passed into function 'ubifs_dump_node()' which replaces
all node dumping places.

Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
---
 fs/ubifs/io.c | 16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

diff --git a/fs/ubifs/io.c b/fs/ubifs/io.c
index 7e4bfaf2871f..8ceb51478800 100644
--- a/fs/ubifs/io.c
+++ b/fs/ubifs/io.c
@@ -225,7 +225,7 @@ int ubifs_is_mapped(const struct ubifs_info *c, int lnum)
 int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
 		     int offs, int quiet, int must_chk_crc)
 {
-	int err = -EINVAL, type, node_len, dump_node = 1;
+	int err = -EINVAL, type, node_len;
 	uint32_t crc, node_crc, magic;
 	const struct ubifs_ch *ch = buf;
 
@@ -278,22 +278,10 @@ int ubifs_check_node(const struct ubifs_info *c, const void *buf, int lnum,
 out_len:
 	if (!quiet)
 		ubifs_err(c, "bad node length %d", node_len);
-	if (type == UBIFS_DATA_NODE && node_len > UBIFS_DATA_NODE_SZ)
-		dump_node = 0;
 out:
 	if (!quiet) {
 		ubifs_err(c, "bad node at LEB %d:%d", lnum, offs);
-		if (dump_node) {
-			ubifs_dump_node(c, buf);
-		} else {
-			int safe_len = min3(node_len, c->leb_size - offs,
-				(int)UBIFS_MAX_DATA_NODE_SZ);
-			pr_err("\tprevent out-of-bounds memory access\n");
-			pr_err("\ttruncated data node length      %d\n", safe_len);
-			pr_err("\tcorrupted data node:\n");
-			print_hex_dump(KERN_ERR, "\t", DUMP_PREFIX_OFFSET, 32, 1,
-					buf, safe_len, 0);
-		}
+		ubifs_dump_node(c, buf);
 		dump_stack();
 	}
 	return err;
-- 
2.25.4