linux-kernel - [PATCH AUTOSEL 6.1 55/85] bpf: Fix a BTF_ID_LIST bug with CONFIG_DEBUG_INFO

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Date:   Sun, 18 Dec 2022 11:01:12 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Yonghong Song <yhs@...com>, kernel test robot <lkp@...el.com>,
        Dan Carpenter <error27@...il.com>,
        Nathan Chancellor <nathan@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Sasha Levin <sashal@...nel.org>, daniel@...earbox.net,
        andrii@...nel.org, martin.lau@...ux.dev, bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 6.1 55/85] bpf: Fix a BTF_ID_LIST bug with CONFIG_DEBUG_INFO_BTF not set

From: Yonghong Song <yhs@...com>

[ Upstream commit beb3d47d1d3d7185bb401af628ad32ee204a9526 ]

With CONFIG_DEBUG_INFO_BTF not set, we hit the following compilation error,
  /.../kernel/bpf/verifier.c:8196:23: error: array index 6 is past the end of the array
  (that has type 'u32[5]' (aka 'unsigned int[5]')) [-Werror,-Warray-bounds]
        if (meta->func_id == special_kfunc_list[KF_bpf_cast_to_kern_ctx])
                             ^                  ~~~~~~~~~~~~~~~~~~~~~~~
  /.../kernel/bpf/verifier.c:8174:1: note: array 'special_kfunc_list' declared here
  BTF_ID_LIST(special_kfunc_list)
  ^
  /.../include/linux/btf_ids.h:207:27: note: expanded from macro 'BTF_ID_LIST'
  #define BTF_ID_LIST(name) static u32 __maybe_unused name[5];
                            ^
  /.../kernel/bpf/verifier.c:8443:19: error: array index 5 is past the end of the array
  (that has type 'u32[5]' (aka 'unsigned int[5]')) [-Werror,-Warray-bounds]
                 btf_id == special_kfunc_list[KF_bpf_list_pop_back];
                           ^                  ~~~~~~~~~~~~~~~~~~~~
  /.../kernel/bpf/verifier.c:8174:1: note: array 'special_kfunc_list' declared here
  BTF_ID_LIST(special_kfunc_list)
  ^
  /.../include/linux/btf_ids.h:207:27: note: expanded from macro 'BTF_ID_LIST'
  #define BTF_ID_LIST(name) static u32 __maybe_unused name[5];
  ...

Fix the problem by increase the size of BTF_ID_LIST to 16 to avoid compilation error
and also prevent potentially unintended issue due to out-of-bound access.

Reported-by: kernel test robot <lkp@...el.com>
Reported-by: Dan Carpenter <error27@...il.com>
Reported-by: Nathan Chancellor <nathan@...nel.org>
Signed-off-by: Yonghong Song <yhs@...com>
Link: https://lore.kernel.org/r/20221123155759.2669749-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 include/linux/btf_ids.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/btf_ids.h b/include/linux/btf_ids.h
index 2aea877d644f..2b9872008428 100644
--- a/include/linux/btf_ids.h
+++ b/include/linux/btf_ids.h
@@ -204,7 +204,7 @@ extern struct btf_id_set8 name;
 
 #else
 
-#define BTF_ID_LIST(name) static u32 __maybe_unused name[5];
+#define BTF_ID_LIST(name) static u32 __maybe_unused name[16];
 #define BTF_ID(prefix, name)
 #define BTF_ID_FLAGS(prefix, name, ...)
 #define BTF_ID_UNUSED
-- 
2.35.1