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. Michal -- 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/
