Messages in this thread Patch in this message | | | From | Kees Cook <> | Subject | [PATCH] s390/purgatory: Do not use fortified string functions | Date | Tue, 30 May 2023 17:34:15 -0700 |
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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 <linux@leemhuis.info> Closes: https://lore.kernel.org/lkml/175578ec-9dec-7a9c-8d3a-43f24ff86b92@leemhuis.info/ Bisected-by: "Joan Bruguera Micó" <joanbrugueram@gmail.com> Fixes: df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Linux Kernel Functional Testing <lkft@linaro.org> Cc: Nathan Chancellor <nathan@kernel.org> Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org> Cc: linux-s390@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> --- 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
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