linux-kernel - [PATCH] potential negative index dereference fix in get_exec

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Message-ID: <20250612131816.1870-1-uncleruc2075@gmail.com>
Date: Thu, 12 Jun 2025 16:18:16 +0300
From: Ruslan Semchenko <uncleruc2075@...il.com>
To: bpf@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	ast@...nel.org,
	daniel@...earbox.net,
	Ruslan Semchenko <uncleruc2075@...il.com>
Subject: [PATCH] potential negative index dereference fix in get_exec_path()

If readlink() fails, len will be -1, which can cause negative indexing
and undefined behavior. This patch ensures that len is set to 0 on
readlink failure, preventing such issues.

Signed-off-by: Ruslan Semchenko <uncleruc2075@...il.com>
---
 tools/bpf/bpf_jit_disasm.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/bpf/bpf_jit_disasm.c b/tools/bpf/bpf_jit_disasm.c
index 1baee9e2aba9..5ab8f80e2834 100644
--- a/tools/bpf/bpf_jit_disasm.c
+++ b/tools/bpf/bpf_jit_disasm.c
@@ -45,6 +45,8 @@ static void get_exec_path(char *tpath, size_t size)
 	assert(path);
 
 	len = readlink(path, tpath, size);
+	if (len < 0)
+		len = 0;
 	tpath[len] = 0;
 
 	free(path);
-- 
2.49.0