diff options
authorAlex Richardson <arichardson@FreeBSD.org>2021-08-02 08:51:34 +0000
committerAlex Richardson <arichardson@FreeBSD.org>2021-08-02 13:33:24 +0000
commit8185be3307232d88ddd1b6468f4ddec54a993f54 (patch)
parentf0712132b68b4271e0602b06ee5f282718bfb8c5 (diff)
libc: Disable ASAN for certain string functions
They deliberately read out-of-bounds values to avoid byte-by-byte loads and check multiple bytes at once. While this will work on x86, it is flagged as an out-of-bounds read with ASAN, so we have to disable instrumentation here. This also causes bounds errors for CHERI, so in CheriBSD we use implementations that avoid OOB reads. Differential Revision: https://reviews.freebsd.org/D31045
1 files changed, 9 insertions, 0 deletions
diff --git a/lib/libc/string/Makefile.inc b/lib/libc/string/Makefile.inc
index 6945155812af..1df3d40e329f 100644
--- a/lib/libc/string/Makefile.inc
+++ b/lib/libc/string/Makefile.inc
@@ -29,6 +29,15 @@ MISRCS+=bcmp.c bcopy.c bzero.c explicit_bzero.c \
SYM_MAPS+= ${LIBC_SRCTOP}/string/Symbol.map
+.if ${MK_ASAN} != "no"
+# These source files deliberately read out of bounds since they assume that
+# out-of-bounds memory accesses that don't cross pages are always legal.
+# Note: While this is fine on x86, it does break when running with CHERI.
+CFLAGS.strlen.c+= -fno-sanitize=address
+CFLAGS.strchrnul.c+= -fno-sanitize=address
+CFLAGS.memchr.c+= -fno-sanitize=address
# machine-dependent string sources
.sinclude "${LIBC_SRCTOP}/${LIBC_ARCH}/string/Makefile.inc"