lkml.org 
[lkml]   [2020]   [Feb]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH AUTOSEL 4.19 226/252] bpf: map_seq_next should always increase position index
Date
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
\
 
 \ /
  Last update: 2020-02-14 17:17    [W:0.534 / U:0.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site