Commit 4af396ae authored Jan 16, 2019 by Stanislav Fomichev Committed by Daniel Borkmann Jan 17, 2019

bpf: zero out build_id for BPF_STACK_BUILD_ID_IP



When returning BPF_STACK_BUILD_ID_IP from stack_map_get_build_id_offset,
make sure that build_id field is empty. Since we are using percpu
free list, there is a possibility that we might reuse some previous
bpf_stack_build_id with non-zero build_id.

Fixes: 615755a7 ("bpf: extend stackmap to save binary_build_id+offset instead of address")
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>

parent 0b698005

kernel/bpf/stackmap.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -314,6 +314,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
		for (i = 0; i < trace_nr; i++) {
		id_offs[i].status = BPF_STACK_BUILD_ID_IP;
		id_offs[i].ip = ips[i];
		memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE);
		}
		return;
		}
		@@ -324,6 +325,7 @@ static void stack_map_get_build_id_offset(struct bpf_stack_build_id *id_offs,
		/* per entry fall back to ips */
		id_offs[i].status = BPF_STACK_BUILD_ID_IP;
		id_offs[i].ip = ips[i];
		memset(id_offs[i].build_id, 0, BPF_BUILD_ID_SIZE);
		continue;
		}
		id_offs[i].offset = (vma->vm_pgoff << PAGE_SHIFT) + ips[i]

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