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[bpf-next,v7,3/8] bpf, iter: Fix the condition on p when calling stop.

Message ID 20220805214821.1058337-4-haoluo@google.com (mailing list archive)
State Superseded
Commit be3bb83dab2df838cd9e681e3e9dcde87bfe4f95
Delegated to: BPF
Headers show
Series bpf: rstat: cgroup hierarchical stats | expand

Checks

Context Check Description
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/apply fail Patch does not apply to bpf-next
bpf/vmtest-bpf-next-PR fail PR summary
bpf/vmtest-bpf-next-VM_Test-1 success Logs for Kernel LATEST on ubuntu-latest with gcc
bpf/vmtest-bpf-next-VM_Test-2 fail Logs for Kernel LATEST on ubuntu-latest with llvm-16
bpf/vmtest-bpf-next-VM_Test-3 fail Logs for Kernel LATEST on z15 with gcc

Commit Message

Hao Luo Aug. 5, 2022, 9:48 p.m. UTC 
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.

Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Hao Luo <haoluo@google.com>
---
 kernel/bpf/bpf_iter.c | 5 +++++
 1 file changed, 5 insertions(+)
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Patch

diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c
index 7e8fd49406f6..4688ba39ef25 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) {