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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Vasily Averin <vvs@virtuozzo.com>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Sasha Levin <sashal@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 226/252] bpf: map_seq_next should always increase position index
Date: Fri, 14 Feb 2020 11:11:21 -0500
Message-ID: <20200214161147.15842-226-sashal@kernel.org> (raw)
In-Reply-To: <20200214161147.15842-1-sashal@kernel.org>

From: Vasily Averin <vvs@virtuozzo.com>

[ Upstream commit 90435a7891a2259b0f74c5a1bc5600d0d64cba8f ]

If seq_file .next fuction does not change position index,
read after some lseek can generate an unexpected output.

See also: https://bugzilla.kernel.org/show_bug.cgi?id=206283

v1 -> v2: removed missed increment in end of function

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/eca84fdd-c374-a154-d874-6c7b55fc3bc4@virtuozzo.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/bpf/inode.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index dc9d7ac8228db..c04815bb15cc1 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -198,6 +198,7 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
 	void *key = map_iter(m)->key;
 	void *prev_key;
 
+	(*pos)++;
 	if (map_iter(m)->done)
 		return NULL;
 
@@ -210,8 +211,6 @@ static void *map_seq_next(struct seq_file *m, void *v, loff_t *pos)
 		map_iter(m)->done = true;
 		return NULL;
 	}
-
-	++(*pos);
 	return key;
 }
 
-- 
2.20.1


      parent reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200214161147.15842-1-sashal@kernel.org>
2020-02-14 16:09 ` [PATCH AUTOSEL 4.19 131/252] tools lib api fs: Fix gcc9 stringop-truncation compilation error Sasha Levin
2020-02-14 16:10 ` [PATCH AUTOSEL 4.19 166/252] bpf: Return -EBADRQC for invalid map type in __bpf_tx_xdp_map Sasha Levin
2020-02-14 16:11 ` [PATCH AUTOSEL 4.19 215/252] selftests: bpf: Reset global state between reuseport test runs Sasha Levin
2020-02-14 16:11 ` Sasha Levin [this message]

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