Commit 3ce3df5d authored Jan 25, 2020 by Vasily Averin Committed by Greg Kroah-Hartman Feb 24, 2020

bpf: map_seq_next should always increase position index

[ 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>

parent 9a178494

kernel/bpf/inode.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -196,6 +196,7 @@ 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;

		@@ -208,8 +209,6 @@ static void map_seq_next(struct seq_file m, void v, loff_t pos)
		map_iter(m)->done = true;
		return NULL;
		}

		++(*pos);
		return key;
		}