On Fri, 2014-11-28 at 14:33 +0100, Michal Marek wrote: > On 2014-11-21 05:22, Peter Teoh wrote: > > This warning was found in v3.18-rc3-68-g20f3963 of Linus git-tree. > > > > SHIPPED scripts/kconfig/zconf.hash.c > > HOSTCC scripts/kconfig/zconf.tab.o > > In file included from scripts/kconfig/zconf.tab.c:2537:0: > > scripts/kconfig/menu.c: In function ‘get_symbol_str’: > > scripts/kconfig/menu.c:590:18: warning: ‘jump’ may be used > > uninitialized in this function [-Wmaybe-uninitialized] > > jump->offset = strlen(r->s); > > ^ > > scripts/kconfig/menu.c:551:19: note: ‘jump’ was declared here > > struct jump_key *jump; > > ^ > > First of all, the warning is bogus (the condition under which 'jump' is > used is stronger than that under which 'jump' is initialized). But since > people have been reporting the warning on and off for some time, we have > to shut it up somehow, as the affected gcc versions are not dying out, > apparently. > > > > - if (head && location && menu == location) > > + if (head && location && (menu == location) && > > (jump)) > > jump->offset = strlen(r->s); > > Let's assume, for the sake of argument, that gcc is right and jump may > be uninitialized here. Then the added check for jump being non-null just > tests an uninitialized variable and thus behaves randomly. It prevents > the code from writing to NULL->offset, but does not prevent it from > writing to <random address>->offset.
Maybe the 'right' thing to do is to mark the xmalloc prototype as "__attribute__((returns_nonnull))" -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
