[Qemu-devel] [PATCH] Making SLIRP code more 64-bit clean

[Scott Pakin]

The attached patch corrects a bug in qemu/slirp/tcp_var.h that defines
the seg_next field in struct tcpcb to be 32 bits wide regardless of
32/64-bitness.  seg_next is assigned a pointer value in
qemu/slirp/tcp_subr.c, then cast back to a pointer in qemu/slirp/tcp_input.c
and dereferenced.  That produces a SIGSEGV on my system.

For more information, see the thread "[ 1881532 ] Network access seg faults
KVM on large-memory machine" on the KVM Bugs page on SourceForge
(http://tinyurl.com/2fxfbx).

Regards,
-- Scott

P.S.  Note: This message was sent to both qemu-devel and kvm-devel.

--- qemu/slirp/tcp_var.h.ORIG   2008-01-28 17:27:09.000000000 -0700
+++ qemu/slirp/tcp_var.h        2008-01-28 17:27:20.000000000 -0700
@@ -40,11 +40,7 @@
 #include "tcpip.h"
 #include "tcp_timer.h"

-#if SIZEOF_CHAR_P == 4
- typedef struct tcpiphdr *tcpiphdrp_32;
-#else
- typedef u_int32_t tcpiphdrp_32;
-#endif
+typedef struct tcpiphdr *tcpiphdrp_32;

 /*
  * Tcp control block, one per tcp; fields: