>Number:         29407
>Category:       kern
>Synopsis:       panic: m_copyback0: read-only
>Confidential:   no
>Severity:       critical
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Feb 16 20:25:00 +0000 2005
>Originator:     Denis Lagno
>Release:        NetBSD 2.99.16
>Organization:
The METAFACH Group
>Environment:
System: NetBSD flam.gado 2.99.16 NetBSD 2.99.16 (FLAM) #0: Wed Feb 16 17:11:04 MSK 2005 dina@flam.gado:/volatile/worksrc/netbsd-current/src/sys/arch/i386/compile/FLAM i386
Architecture: i386
Machine: i386
>Description:
when I try to access ftp I get panic:

panic: m_copyback0: read-only
Stopped at      netbsd:cpu_Debugger+0x4:        popl    %ebp
db{1}> bt
cpu_Debugger(c04bdfdc,cbe3a54c,a,0,0) at netbsd:cpu_Debugger+0x4
panic(c04ba15a,cbe3a56f,75,c04adc07,0) at netbsd:panic+0x12a
m_copyback0(cbe3a5b8,34,1c,cbe3a6a8,9) at netbsd:m_copyback0+0x6d4
m_copyback(c1b27f00,34,1c,cbe3a6a8,13) at netbsd:m_copyback+0x42
ippr_ftp_port(cbe3aad8,cba79010,c1f79a00,c1f79808,1b) at netbsd:ippr_ftp_port+0x31e
ippr_ftp_client(cbe3aad8,cba79010,c1f79a00,c1f79800,1b) at netbsd:ippr_ftp_client+0x1ea
ippr_ftp_process(cbe3aad8,c1f79a00,c1f79800,0,c1b27f00) at netbsd:ippr_ftp_process+0x69a
ippr_ftp_out(cbe3aad8,c1f70c00,c1f79a00,c0155ce3,c1f79a54) at netbsd:ippr_ftp_out+0x5d
appr_check(cbe3aad8,c1f79a00,9b8c,c01490e8,1) at netbsd:appr_check+0x1c8
fr_natout(cbe3aad8,c1f79a00,1,1,dbe98cc) at netbsd:fr_natout+0x15f
fr_checknatout(cbe3aad8,cbe3aad4,cbe3aad8,0,4) at netbsd:fr_checknatout+0x11a
fr_check(cba79010,14,c1f48400,1,cbe3abe0) at netbsd:fr_check+0x495
fr_check_wrapper(0,cbe3abe0,c1f48400,2,a) at netbsd:fr_check_wrapper+0x62
pfil_run_hooks(c05515a0,cbe3ac38,c1f48400,2,c061f61c) at netbsd:pfil_run_hooks+0x98
ip_output(c1b27f00,0,c05515d4,1,0) at netbsd:ip_output+0x503
ip_forward(c1b27f00,0,c1d3003c,1,c0528e14) at netbsd:ip_forward+0x189
ip_input(c1b27f00,7,cbe3af50,0,c0100e31) at netbsd:ip_input+0x2de
ipintr(cbe30010,30,c04f0010,10,cbe37000) at netbsd:ipintr+0x88
DDB lost frame for netbsd:Xsoftnet+0x49, trying 0xcbe3af58
Xsoftnet() at netbsd:Xsoftnet+0x49
--- interrupt ---
Bad frame pointer: 0xc052d4e0
0x246:

>How-To-Repeat:
From scarce observations this panic arises when my first ftp access
is from some other host in the local network.  The host that panics
is a gateway to Internet.  I use NAT and ipsec.
I first observed this panic with week-old -current.  I updated system
and the panic persist.
>Fix:
N/A