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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id x3-20020aa79563000000b005818d4284aasm16046250pfq.160.2023.01.05.11.26.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Jan 2023 11:26:50 -0800 (PST) From: Kees Cook To: Alexei Starovoitov Cc: Kees Cook , Daniel Borkmann , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , "Gustavo A. R. Silva" , bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] bpf: Replace 0-length arrays with flexible arrays Date: Thu, 5 Jan 2023 11:26:47 -0800 Message-Id: <20230105192646.never.154-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2101; h=from:subject:message-id; bh=V+hDTvfLNktsOza7//a0ww3JjY/DO434Oi3YuneAQho=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBjtyR3frN3HKMkFYai/Tm7ow/5jyykqQkgn4p54zvI 3udqhk6JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCY7ckdwAKCRCJcvTf3G3AJiVXD/ oDGiZsOyCTBvLW5TFiKe3edkbxbWHr734/G3YbQEr15ayjIYmPo4HRfPl5f4ILDNVy24KjBoUFo9pB coVD7DTnVaFqeQ+kIbE59nyjzZZuUstSyyrFAFaps2VjYlcxhQclBM8ri1GFaIyeeAeR5Qs/IPdlMn dfxzky3v1L3HQQLLG0h26sTRl+pgOhaN4hiihyxZZV8rYS1nM++DZyMjbUQh+7lO525XIOd1p5Mk0j YHEwojOP1BDNZ+/5RgCCPCyPzKhQyOB4glMRpff7BPpi/gX1moSO9xjQOxp0U/nrB/zR267fq8DCVm zeRSUBCdQdpM05UACFsqZJHwiiZerLz5/rgFgiehgoulnCiidE19JcAYOMqBI9mJqx/yTPCWjxpHGr 89uZ9V8XbgjBTViH2Xvt/GHKdKXjfMYgolk3dblHqteV/PQ287MVj0V3uO+WumVw1TY+Fx4TsJfdyS DoNCgswbqTMlBlxy3IySs5RDgp/viDh0jA9TDeolIk/9rYQACGi6HbaoVnmuEF1UWMAaKgZFbLv4gw z4Y0hX5Dp7dw34matjSvTPGwhiVP0io9YetucAqYbuVziv6heiXkyobM4g2alSdqn6rlsKkV0h4SBx H8qunve472K7XsC1zmNiU1mTDwRwXYbu2D3KNs2eAAicfhq9o18tJj/R5Hxg== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Zero-length arrays are deprecated[1]. Replace struct bpf_array's union of 0-length arrays with flexible arrays. (How are the sizes of these arrays verified?) Detected with GCC 13, using -fstrict-flex-arrays=3D3: arch/x86/net/bpf_jit_comp.c: In function 'bpf_tail_call_direct_fixup': arch/x86/net/bpf_jit_comp.c:606:37: warning: array subscript is o= utside array bounds of 'void *[0]' [-Warray-bounds=3D] 606 | target =3D array->ptrs[poke->tail_call.key]; | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~ In file included from include/linux/filter.h:9, from arch/x86/net/bpf_jit_comp.c:9: include/linux/bpf.h:1527:23: note: while referencing 'ptrs' 1527 | void *ptrs[0] __aligned(8); | ^~~~ [1] https://www.kernel.org/doc/html/latest/process/deprecated.html#zero-len= gth-and-one-element-arrays Cc: Alexei Starovoitov Cc: Daniel Borkmann Cc: John Fastabend Cc: Andrii Nakryiko Cc: Martin KaFai Lau Cc: Song Liu Cc: Yonghong Song Cc: KP Singh Cc: Stanislav Fomichev Cc: Hao Luo Cc: Jiri Olsa Cc: "Gustavo A. R. Silva" Cc: bpf@vger.kernel.org Signed-off-by: Kees Cook Acked-by: Stanislav Fomichev --- include/linux/bpf.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 3de24cfb7a3d..2131000f711e 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1523,9 +1523,9 @@ struct bpf_array { u32 index_mask; struct bpf_array_aux *aux; union { - char value[0] __aligned(8); - void *ptrs[0] __aligned(8); - void __percpu *pptrs[0] __aligned(8); + DECLARE_FLEX_ARRAY(char, value) __aligned(8); + DECLARE_FLEX_ARRAY(void *, ptrs) __aligned(8); + DECLARE_FLEX_ARRAY(void __percpu *, pptrs) __aligned(8); }; }; =20 --=20 2.34.1