netdev - [bpf-next v2] libbpf: fix BPF_LOG_BUF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20190419233720.3406-1-robert.mccabe@rockwellcollins.com>
Date:   Fri, 19 Apr 2019 18:37:20 -0500
From:   robert.mccabe@...kwellcollins.com
To:     netdev@...r.kernel.org
Cc:     robertjmccabe@...il.com, robert.mccabe@...kwellcollins.com,
        McCabe@...kwellcollins.com
Subject: [bpf-next v2] libbpf: fix BPF_LOG_BUF_SIZE off-by-one error

From: <robert.mccabe@...kwellcollins.com>

The BPF_PROG_LOAD condition for kernel version <= 5.1 is

   log->len_total > UINT_MAX >> 8 /* (16 * 1024 * 1024) - 1 */

Signed-off-by: McCabe, Robert J <robert.mccabe@...kwellcollins.com>
---
 tools/lib/bpf/bpf.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/lib/bpf/bpf.h b/tools/lib/bpf/bpf.h
index bc30783d1403..62d67caa7aea 100644
--- a/tools/lib/bpf/bpf.h
+++ b/tools/lib/bpf/bpf.h
@@ -92,7 +92,7 @@ struct bpf_load_program_attr {
 #define MAPS_RELAX_COMPAT	0x01

 /* Recommend log buffer size */
-#define BPF_LOG_BUF_SIZE (16 * 1024 * 1024) /* verifier maximum in kernels <= 5.1 */
+#define BPF_LOG_BUF_SIZE (UINT32_MAX >> 8) /* verifier maximum in kernels <= 5.1 */
 LIBBPF_API int
 bpf_load_program_xattr(const struct bpf_load_program_attr *load_attr,
 		       char *log_buf, size_t log_buf_sz);
--
2.17.1