linux-kernel - [PATCH] ipv4: only allow increasing fib_info_hash

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Message-Id: <20211012110658.10166-1-zhangkaiheb@126.com>
Date:   Tue, 12 Oct 2021 19:06:58 +0800
From:   zhang kai <zhangkaiheb@....com>
To:     davem@...emloft.net
Cc:     yoshfuji@...ux-ipv6.org, dsahern@...nel.org, kuba@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        zhang kai <zhangkaiheb@....com>
Subject: [PATCH] ipv4: only allow increasing fib_info_hash_size

and when failed to allocate memory, check fib_info_hash_size.

Signed-off-by: zhang kai <zhangkaiheb@....com>
---
 net/ipv4/fib_semantics.c | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/net/ipv4/fib_semantics.c b/net/ipv4/fib_semantics.c
index a632b66bc..7547708a9 100644
--- a/net/ipv4/fib_semantics.c
+++ b/net/ipv4/fib_semantics.c
@@ -1403,17 +1403,20 @@ struct fib_info *fib_create_info(struct fib_config *cfg,
 
 		if (!new_size)
 			new_size = 16;
-		bytes = new_size * sizeof(struct hlist_head *);
-		new_info_hash = fib_info_hash_alloc(bytes);
-		new_laddrhash = fib_info_hash_alloc(bytes);
-		if (!new_info_hash || !new_laddrhash) {
-			fib_info_hash_free(new_info_hash, bytes);
-			fib_info_hash_free(new_laddrhash, bytes);
-		} else
-			fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
-
-		if (!fib_info_hash_size)
-			goto failure;
+
+		if (new_size > fib_info_hash_size) {
+			bytes = new_size * sizeof(struct hlist_head *);
+			new_info_hash = fib_info_hash_alloc(bytes);
+			new_laddrhash = fib_info_hash_alloc(bytes);
+			if (!new_info_hash || !new_laddrhash) {
+				fib_info_hash_free(new_info_hash, bytes);
+				fib_info_hash_free(new_laddrhash, bytes);
+
+				if (!fib_info_hash_size)
+					goto failure;
+			} else
+				fib_info_hash_move(new_info_hash, new_laddrhash, new_size);
+		}
 	}
 
 	fi = kzalloc(struct_size(fi, fib_nh, nhs), GFP_KERNEL);
-- 
2.17.1