Wireshark mailing list archives
Re: Familiar with gtk/sctp_graph_dlg.c?
From: Michael Tüxen <Michael.Tuexen () lurchi franken de>
Date: Tue, 26 Apr 2011 10:12:39 +0200
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-request () wireshark org?subject=unsubscribe
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Current thread:
- Familiar with gtk/sctp_graph_dlg.c? Stephen Fisher (Apr 25)
- Re: [Wireshark-dev] Familiar with gtk/sctp_graph_dlg.c? Chris Maynard (Apr 25)
- Re: Familiar with gtk/sctp_graph_dlg.c? Michael Tüxen (Apr 25)
- Re: Familiar with gtk/sctp_graph_dlg.c? Michael Tüxen (Apr 25)
- Re: Familiar with gtk/sctp_graph_dlg.c? Guy Harris (Apr 25)
- Re: Familiar with gtk/sctp_graph_dlg.c? Michael Tüxen (Apr 26)
- Re: [Wireshark-dev] Familiar with gtk/sctp_graph_dlg.c? Christopher Maynard (Apr 26)
- Re: Familiar with gtk/sctp_graph_dlg.c? Guy Harris (Apr 26)
- Re: Familiar with gtk/sctp_graph_dlg.c? Michael Tüxen (Apr 26)
- Re: Familiar with gtk/sctp_graph_dlg.c? Guy Harris (Apr 25)
- Re: [Wireshark-dev] Familiar with gtk/sctp_graph_dlg.c? Chris Maynard (Apr 25)
- Re: Familiar with gtk/sctp_graph_dlg.c? Michael Tüxen (Apr 26)
- Re: [Wireshark-dev] Familiar with gtk/sctp_graph_dlg.c? Chris Maynard (Apr 26)
- Re: [Wireshark-dev] Familiar with gtk/sctp_graph_dlg.c? Chris Maynard (Apr 26)