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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id fa9-20020a17090af0c900b0027360359b70sm12746037pjb.48.2023.10.10.16.56.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Oct 2023 16:56:15 -0700 (PDT) From: Kees Cook To: Kent Overstreet Cc: Kees Cook , Brian Foster , linux-bcachefs@vger.kernel.org, kernel test robot , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] bcachefs: Refactor bkey_i to use a flexible array Date: Tue, 10 Oct 2023 16:56:12 -0700 Message-Id: <20231010235609.work.594-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3104; i=keescook@chromium.org; h=from:subject:message-id; bh=NfdMvLiG7AP1UedLusFnQqnFA5ZiezwfWaxIM+i+tRA=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlJeScSUyz3NZfxL43a/8LlJ7zzNz0b3ul121Gl upxtR3bHn2JAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZSXknAAKCRCJcvTf3G3A JoNbD/4whEZUDyONG/LAxsYi0gic1AeiW2Z37d9rJL7Rfib1H9dD+bou+gfPycZoOl1o5d0cZCY bCtHhYf5PFfCLaRRmUGRKtfc41Wgc1b3VFfadHluT7vP26PMUnNlvw7NFYJvT4/LDXDBOML20YI iYnbwgq/WlTapLBDULe9PutZ67M7Y4f6g56i2801W0pQwW0v1ue08ShxGEvHdCFLwJMYTHjFfJi 27ylDaeszwHHC80vtS9UAnrpllO5aXideMB2wAg55qT8J+LoxVqoixEcJ9vwiK9p/7bn78iJjWS uYDQV24ERXP/K3lHSAuuqhi3PMGtiCBvyZvI0aUZmV0buzqlcN4AuAEjBhrGlxRoil/KJrPKfbI UEj7HsIliQ5cCGXEXwaJPzifXGa10MgWAJSBlOUfpzkUMrwVyMDW7MwRkayQ3M8bOAnhLFYqnq1 Io+kKq29sLs+DBo9vTApgL4Rod2o+uFrF2EIDI/jrl+6pqBjxojxCzNVgH7AZzixKBFq1VSjw2e e9Ff+cEZXZ878o+k81FTz42FxT+DT/zlqiD+/KGPhOnj5J5LLXILogAps2eLpfi2B5fm5Ty4Hbj GsfXuU6y0XIX4wDT8xmB+O5SzFTAaDeSvb/Td4xmnQmqhxaVyonefLCpkR+kVcyX6nDGtEo6ZV4 hPufHRL lXjHsLzg== 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" The memcpy() in bch2_bkey_append_ptr() is operating on an embedded fake flexible array. Instead, make it explicit, and convert the memcpy to target the flexible array instead. Fixes the W=3D1 warning seen for -Wstringop-overflow: In file included from include/linux/string.h:254, from include/linux/bitmap.h:11, from include/linux/cpumask.h:12, from include/linux/smp.h:13, from include/linux/lockdep.h:14, from include/linux/radix-tree.h:14, from include/linux/backing-dev-defs.h:6, from fs/bcachefs/bcachefs.h:182: fs/bcachefs/extents.c: In function 'bch2_bkey_append_ptr': include/linux/fortify-string.h:57:33: warning: writing 8 bytes into a re= gion of size 0 [-Wstringop-overflow=3D] 57 | #define __underlying_memcpy __builtin_memcpy | ^ include/linux/fortify-string.h:648:9: note: in expansion of macro '__und= erlying_memcpy' 648 | __underlying_##op(p, q, __fortify_size); = \ | ^~~~~~~~~~~~~ include/linux/fortify-string.h:693:26: note: in expansion of macro '__fo= rtify_memcpy_chk' 693 | #define memcpy(p, q, s) __fortify_memcpy_chk(p, q, s, = \ | ^~~~~~~~~~~~~~~~~~~~ fs/bcachefs/extents.c:235:17: note: in expansion of macro 'memcpy' 235 | memcpy((void *) &k->v + bkey_val_bytes(&k->k), | ^~~~~~ fs/bcachefs/bcachefs_format.h:287:33: note: destination object 'v' of si= ze 0 287 | struct bch_val v; | ^ Cc: Kent Overstreet Cc: Brian Foster Cc: linux-bcachefs@vger.kernel.org Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202309192314.VBsjiIm5-lkp@int= el.com/ Signed-off-by: Kees Cook --- fs/bcachefs/bcachefs_format.h | 5 ++++- fs/bcachefs/extents.h | 2 +- 2 files changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/bcachefs/bcachefs_format.h b/fs/bcachefs/bcachefs_format.h index f0d130440baa..f5e8cb43697b 100644 --- a/fs/bcachefs/bcachefs_format.h +++ b/fs/bcachefs/bcachefs_format.h @@ -300,7 +300,10 @@ struct bkey_i { __u64 _data[0]; =20 struct bkey k; - struct bch_val v; + union { + struct bch_val v; + DECLARE_FLEX_ARRAY(__u8, bytes); + }; }; =20 #define KEY(_inode, _offset, _size) \ diff --git a/fs/bcachefs/extents.h b/fs/bcachefs/extents.h index 7ee8d031bb6c..6248e17bbac5 100644 --- a/fs/bcachefs/extents.h +++ b/fs/bcachefs/extents.h @@ -642,7 +642,7 @@ static inline void bch2_bkey_append_ptr(struct bkey_i *= k, struct bch_extent_ptr =20 ptr.type =3D 1 << BCH_EXTENT_ENTRY_ptr; =20 - memcpy((void *) &k->v + bkey_val_bytes(&k->k), + memcpy(&k->bytes[bkey_val_bytes(&k->k)], &ptr, sizeof(ptr)); k->k.u64s++; --=20 2.34.1