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.c... 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 ecf42bec38c00..6f22e0e74ef24 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -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; }