[PATCH 6.0 0952/1073] bpf: Fix a BTF_ID_LIST bug with CONFIG_DEBUG_INFO_BTF not set

Greg Kroah-Hartman
2022-12-28T16:48:02Z

From: Yonghong Song <yhs@fb.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@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/r/20221123155759.2669749-1-yhs@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.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