build failure with -D_FORTIFY_SOURCE=2

Ondrej Zajicek santiago at
Sun Oct 25 22:32:33 CET 2015

On Sun, Oct 25, 2015 at 05:31:52PM +0300, Vladimir Lettiev wrote:
> Hi.
> Just got a build failure with recent gcc with enabled option FORTIFY_SOURCE=2:
> In function 'strncpy',
>     inlined from 'rip_outgoing_authentication' at ../../../proto/rip/auth.c:134:5:
> /usr/include/bits/string3.h:120:10: error: call to __builtin___strncpy_chk will always overflow destination buff
> There is proto/rip/auth.c:134:
>     strncpy( (char *) (&block->packetlen), passwd->password, 16);
> destination packetlen is u16, so gcc thinks it is overflow.
> Is it possible to change strncpy with memcpy?

No, memcpy would not work.

You could replace '(char *) (&block->packetlen)' with:

(char *) block + OFFSETOF(struct rip_block_auth, packetlen)

Elen sila lumenn' omentielvo

Ondrej 'Santiago' Zajicek (email: santiago at
OpenPGP encrypted e-mails preferred (KeyID 0x11DEADC3,
"To err is human -- to blame it on a computer is even more so."
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