Date: Sun, 02 Dec 2012 16:37:23 +0100 From: Dimitry Andric <dim@FreeBSD.org> To: Andriy Gapon <avg@FreeBSD.org> Cc: Garrett Cooper <yanegomi@gmail.com>, Taku YAMAMOTO <taku@tackymt.homeip.net>, freebsd-current@FreeBSD.org Subject: Re: A suspicious warning in sys/boot/zfs/zfsimpl.c Message-ID: <50BB75B3.6070505@FreeBSD.org> In-Reply-To: <50B9E47F.6070005@FreeBSD.org> References: <20120703102142.6554b10e.taku@tackymt.homeip.net> <CAGH67wQ3BtyaYZNGxT_UW%2Be=CVR0V6V%2BZc027bDgDNv6fK66eg@mail.gmail.com> <50B9E47F.6070005@FreeBSD.org>
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On 2012-12-01 12:05, Andriy Gapon wrote: > on 01/12/2012 12:59 Garrett Cooper said the following: >> On Mon, Jul 2, 2012 at 6:21 PM, Taku YAMAMOTO <taku@tackymt.homeip.net> wrote: >>> When I built the world as of r237813, clang reported a warning which >>> caught my attention. >>> >>> ===> sys/boot/zfs (all) >>> clang -O2 -pipe -march=pentium4 -DBOOTPROG=\"zfsloader\" -I/usr/src/sys/boot/zfs/../common -I/usr/src/sys/boot/zfs/../.. -I. -I/usr/src/sys/boot/zfs/../../../lib/libstand -I/usr/src/sys/boot/zfs/../../cddl/boot/zfs -ffreestanding -mpreferred-stack-boundary=2 -mno-mmx -mno-3dnow -mno-sse -mno-sse2 -mno-sse3 -msoft-float -Wformat -Wall -DNDEBUG -std=gnu99 -Qunused-arguments -c /usr/src/sys/boot/zfs/zfs.c -o zfs.o >>> In file included from /usr/src/sys/boot/zfs/zfs.c:48: >>> /usr/src/sys/boot/zfs/zfsimpl.c:2033:19: warning: array index 264 is past the end of the array (which contains 192 elements) [-Warray-bounds] >>> memcpy(path, &dn.dn_bonus[sizeof(znode_phys_t)], >>> ^ ~~~~~~~~~~~~~~~~~~~~ >>> /usr/src/sys/boot/zfs/../../cddl/boot/zfs/zfsimpl.h:788:2: note: array 'dn_bonus' declared here >>> uint8_t dn_bonus[DN_MAX_BONUSLEN - sizeof (blkptr_t)]; >>> ^ >>> >>> I don't have a zfs-powered machine, so I'm not sure whether this >>> warning is false-positive or not. >> >> I'm seeing the same warnings trying to build HEAD r242903 with >> clang on amd64. Andriy CCed. > > I believe that there is no actual problem there. Indeed. The ZFS code seems to be using the dnode_phys_t::dn_bonus field as a sort of flexible struct member. These specific warnings can be ignored, or turned off.
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