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().
Initialization of env->scc_cnt was omitted in
verifier.c:compute_scc(), which is fixed by this commit.
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 <axboe@xxxxxxxxx>
Closes: https://lore.kernel.org/bpf/CAADnVQKXUWg9uRCPD5ebRXwN4dmBCRUFFM7kN=GxymYz3zU25A@xxxxxxxxxxxxxx/T/
Suggested-by: Alexei Starovoitov <alexei.starovoitov@xxxxxxxxx>
Signed-off-by: Eduard Zingerman <eddyz87@xxxxxxxxx>
---
kernel/bpf/verifier.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 0806295945e4..c4f69a9e9af6 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 @@ static int compute_scc(struct bpf_verifier_env *env)
err = -ENOMEM;
goto exit;
}
+ env->scc_cnt = next_scc_id;
exit:
kvfree(stack);
kvfree(pre);
--
2.50.1
