[PATCH bpf-next v2 3/8] bpf, iter: Fix the condition on p when calling stop.

Yosry Ahmed
2022-06-10T19:44:30Z

From: Hao Luo <haoluo@google.com>

In bpf_seq_read, seq->op->next() could return an ERR and jump to
the label stop. However, the existing code in stop does not handle
the case when p (returned from next()) is an ERR. Adds the handling
of ERR of p by converting p into an error and jumping to done.

Because all the current implementations do not have a case that
returns ERR from next(), so this patch doesn't have behavior changes
right now.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Yosry Ahmed <yosryahmed@google.com>
---
kernel/bpf/bpf_iter.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index d5d96ceca1058..1585caf7c7200 100644
--- a/kernel/bpf/bpf_iter.c
+++ b/kernel/bpf/bpf_iter.c
@@ -198,6 +198,11 @@ static ssize_t bpf_seq_read(struct file *file, char __user *buf, size_t size,
}
stop:
offs = seq->count;
+ if (IS_ERR(p)) {
+ seq->op->stop(seq, NULL);
+ err = PTR_ERR(p);
+ goto done;
+ }
/* bpf program called if !p */
seq->op->stop(seq, p);
if (!p) {
--
2.36.1.476.g0c4daa206d-goog