From 1b30d44417278196a90c79244bb43e8428586345 Mon Sep 17 00:00:00 2001 From: Eduard Zingerman Date: Fri, 1 Aug 2025 16:23:30 -0700 Subject: [PATCH] bpf: Fix memory leak of bpf_scc_info objects env->scc_info array contains references to bpf_scc_info objects allocated lazily in verifier.c:scc_visit_alloc(). env->scc_cnt was supposed to track env->scc_info array size in order to free referenced objects in verifier.c:free_states(). Fix initialization of env->scc_cnt that was omitted in verifier.c:compute_scc(). To reproduce the bug: - build with CONFIG_DEBUG_KMEMLEAK - boot and load bpf program with loops, e.g.: ./veristat -q pyperf180.bpf.o - initiate memleak scan and check results: echo scan > /sys/kernel/debug/kmemleak cat /sys/kernel/debug/kmemleak Fixes: c9e31900b54c ("bpf: propagate read/precision marks over state graph backedges") Reported-by: Jens Axboe Closes: https://lore.kernel.org/bpf/CAADnVQKXUWg9uRCPD5ebRXwN4dmBCRUFFM7kN=GxymYz3zU25A@mail.gmail.com/T/ Suggested-by: Alexei Starovoitov Tested-by: Jens Axboe Signed-off-by: Eduard Zingerman Link: https://lore.kernel.org/r/20250801232330.1800436-1-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0806295945e40..c4f69a9e9af69 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -23114,6 +23114,8 @@ static void free_states(struct bpf_verifier_env *env) for (i = 0; i < env->scc_cnt; ++i) { info = env->scc_info[i]; + if (!info) + continue; for (j = 0; j < info->num_visits; j++) free_backedges(&info->visits[j]); kvfree(info); @@ -24554,6 +24556,7 @@ dfs_continue: err = -ENOMEM; goto exit; } + env->scc_cnt = next_scc_id; exit: kvfree(stack); kvfree(pre); -- 2.47.2