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[198.0.35.241]) by smtp.gmail.com with ESMTPSA id j9-20020aa783c9000000b00640defda6d2sm2122043pfn.207.2023.05.30.17.34.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 May 2023 17:34:17 -0700 (PDT) From: Kees Cook To: Heiko Carstens Cc: Kees Cook , Thorsten Leemhuis , =?UTF-8?q?Joan=20Bruguera=20Mic=C3=B3?= , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Masahiro Yamada , Linux Kernel Functional Testing , Nathan Chancellor , "Gustavo A. R. Silva" , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH] s390/purgatory: Do not use fortified string functions Date: Tue, 30 May 2023 17:34:15 -0700 Message-Id: <20230531003414.never.050-kees@kernel.org> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Developer-Signature: v=1; a=openpgp-sha256; l=1932; h=from:subject:message-id; bh=3fzKBd1zujjv+SG6w7I7Y4v19AUyPzbSQe4ghFml234=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBkdpYGW+0BpAnJwD3TP9pZ65CDHX9QrJD+lbCVA5TY Tzp9khaJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZHaWBgAKCRCJcvTf3G3AJs0cEA CiZUiBN0H8c1+y8rgHJICYG74xR2GG2LajP/p9SrpbxhpissdlyzA57ENFt0LF87e87DBVNtNV0Iay E09uGdf/Zb5Dr8ikL26Vyeug7TXOeWjSV9gTC43wG4mg7o4R1G2/SzQ83HJG71ey9w4eyINCv+2Yg4 zDbI6pTvlGUAqkH6bW+lxWZJcIGXHrP4rBB05IAw9lA8KVr+wCznrYPz+tEufVcLywElmC0WqsFHzr rs+VuthL0YG+s97qw3qexp6w4YHh7V1wIls0cHvOto/y3kT5PlyKijuqG+7f6BsHMRH7giF7x5C5un sgOEOY0v3OCHXNIqwm8wwNsWI3JOky0PRo+Sz8Vsh3dDJHk1JZLAj0K5/RWrh47BpmmgjjhI0Uq2zL g/WcmyITo50/UayP+VSE6XtCK8496iNV7lXQ7Xr7AbY6MG+XsILyCKHpv/kyKN8BcKc58UFQGOlq5D pwCuncOlx3OK2bbrCaYZeTAF8cjyJOYRDV4s9cShT/AnE0+dQ3H9krl+o5hjHWk5XTW95ztSVoY92v afgzazipmjg3I+bkS06U/i/J6cwWw6K1TjS+4QUTEYZw2dtPTN3iw9rEtTII+8FFqvVDmsKwE9u75b QO9CYHiDZ+eElpDqrzjXP7bj1IUfjpU1+3FFH2H4o6++IWEeJ31XoEjgzgRQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org With the addition of -fstrict-flex-arrays=3, struct sha256_state's trailing array is no longer ignored by CONFIG_FORTIFY_SOURCE: struct sha256_state { u32 state[SHA256_DIGEST_SIZE / 4]; u64 count; u8 buf[SHA256_BLOCK_SIZE]; }; This means that the memcpy() calls with "buf" as a destination in sha256.c's code will attempt to perform run-time bounds checking, which could lead to calling missing functions, specifically a potential WARN_ONCE, which isn't callable from purgatory. Reported-by: Thorsten Leemhuis Closes: https://lore.kernel.org/lkml/175578ec-9dec-7a9c-8d3a-43f24ff86b92@leemhuis.info/ Bisected-by: "Joan Bruguera Micó" Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") Cc: Heiko Carstens Cc: Vasily Gorbik Cc: Alexander Gordeev Cc: Christian Borntraeger Cc: Sven Schnelle Cc: Masahiro Yamada Cc: Linux Kernel Functional Testing Cc: Nathan Chancellor Cc: "Gustavo A. R. Silva" Cc: linux-s390@vger.kernel.org Signed-off-by: Kees Cook --- arch/s390/purgatory/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/s390/purgatory/Makefile b/arch/s390/purgatory/Makefile index 32573b4f9bd2..cf14740abd1c 100644 --- a/arch/s390/purgatory/Makefile +++ b/arch/s390/purgatory/Makefile @@ -10,7 +10,7 @@ PURGATORY_OBJS = $(addprefix $(obj)/,$(purgatory-y)) $(obj)/sha256.o: $(srctree)/lib/crypto/sha256.c FORCE $(call if_changed_rule,cc_o_c) -CFLAGS_sha256.o := -D__DISABLE_EXPORTS +CFLAGS_sha256.o := -D__DISABLE_EXPORTS -D__NO_FORTIFY $(obj)/mem.o: $(srctree)/arch/s390/lib/mem.S FORCE $(call if_changed_rule,as_o_S) -- 2.34.1