On Apr 26, 2011, at 6:23 AM, Guy Harris wrote: > > On Apr 25, 2011, at 3:01 PM, Michael Tüxen wrote: > >> dup_list = (guint32 *)((char *)sack_header + 16 + (nr * sizeof(struct gaps))) > > Clang likes something that doesn't involve casting a "char *", which is not > guaranteed to contain an address that's 4-byte aligned, to a "guint32 *", > which is a pointer that's supposed to be 4-byte aligned... > > ...and that, on at least some architectures, *MUST* be 4-byte aligned in > order for dereferences of it to work! The fields in the packet are 4 byte aligned. But if the whole structure might not... So should we copy them?
Best regards Michael > > One such architecture is SPARC, which traps on unaligned references. I think > at least some versions of ARM are other such architectures; I don't think it > traps on unaligned accesses, but it might, for example, just act as if the > lower 2 bits of the address are 0. > > Unless sack_header is *guaranteed* to be aligned on a 4-byte boundary, that > code is unsafe. > ___________________________________________________________________________ > Sent via: Wireshark-dev mailing list <wireshark-dev@wireshark.org> > Archives: http://www.wireshark.org/lists/wireshark-dev > Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev > mailto:wireshark-dev-requ...@wireshark.org?subject=unsubscribe > ___________________________________________________________________________ Sent via: Wireshark-dev mailing list <wireshark-dev@wireshark.org> Archives: http://www.wireshark.org/lists/wireshark-dev Unsubscribe: https://wireshark.org/mailman/options/wireshark-dev mailto:wireshark-dev-requ...@wireshark.org?subject=unsubscribe
