linux-kernel - [PATCH bpf-next] selftests/bpf: Bump and validate MAX

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Date:   Thu,  6 Jul 2023 16:22:28 +0200
From:   Björn Töpel <bjorn@...nel.org>
To:     Andrii Nakryiko <andrii@...nel.org>,
        Mykola Lysenko <mykolal@...com>, bpf@...r.kernel.org,
        netdev@...r.kernel.org
Cc:     Björn Töpel <bjorn@...osinc.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        linux-kselftest@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH bpf-next] selftests/bpf: Bump and validate MAX_SYMS

From: Björn Töpel <bjorn@...osinc.com>

BPF tests that load /proc/kallsyms, e.g. bpf_cookie, will perform a
buffer overrun if the number of syms on the system is larger than
MAX_SYMS.

Bump the MAX_SYMS to 400000, and add a runtime check that bails out if
the maximum is reached.

Signed-off-by: Björn Töpel <bjorn@...osinc.com>
---
 tools/testing/selftests/bpf/trace_helpers.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/bpf/trace_helpers.c b/tools/testing/selftests/bpf/trace_helpers.c
index 9b070cdf44ac..f83d9f65c65b 100644
--- a/tools/testing/selftests/bpf/trace_helpers.c
+++ b/tools/testing/selftests/bpf/trace_helpers.c
@@ -18,7 +18,7 @@
 #define TRACEFS_PIPE	"/sys/kernel/tracing/trace_pipe"
 #define DEBUGFS_PIPE	"/sys/kernel/debug/tracing/trace_pipe"
 
-#define MAX_SYMS 300000
+#define MAX_SYMS 400000
 static struct ksym syms[MAX_SYMS];
 static int sym_cnt;
 
@@ -46,6 +46,9 @@ int load_kallsyms_refresh(void)
 			break;
 		if (!addr)
 			continue;
+		if (i >= MAX_SYMS)
+			return -EFBIG;
+
 		syms[i].addr = (long) addr;
 		syms[i].name = strdup(func);
 		i++;

base-commit: fd283ab196a867f8f65f36913e0fadd031fcb823
-- 
2.39.2