[AGENT++] R: R: R: pure virtual method called
Michele Marcon
M.Marcon at riello-ups.com
Tue Feb 22 10:17:48 CET 2011
Hi,
I've tried the patch,
+ if (!lookupResult->h_addr_list[0])
+ {
+ debugprintf(1, "Error resolving host name");
+ return false;
+ }
+
This if evaluates to false, therefore h_addr_list is validated. However, the memcpy still crashes.
Here is the gdb output (please note that herrno returned by gethostbyname_r() is == 1; that should mean that the function has encountered some error):
> whatis herrno
type = int
>>>>>>cb_gdb:
> output herrno
1>>>>>>cb_gdb:
> info locals
ipAddr = {s_addr = 0}
lookupResult = (hostent *) 0xbec4f608
buf = "\177\000\000\001\000\000\000\000\000\000\000\000\000000\000\000\000\000\000127.0.0.1\000EK250\000localhost.localdomain\000localhost\000\000 <repeats 1668 times>, "000\000\000\000Linux", '\0' <repeats 60 times>, "EK250", '\0' <repeats 60 times>, "2.6.19.2-EK20100211", '\0' <repeats 46 times>, "#1 PREEMPT Thu Feb 11 17:42:54"...
herrno = 1
lookup_buf = {h_name = 0xbec4ede9 "EK250", h_aliases = 0xbec4ee10, h_addrtype = 2, h_length = 4, h_addr_list = 0xbec4edd7}
ds = '\0' <repeats 46 times>, "(none)\000\000\000\000\000\000\000\000"
>>>>>>cb_gdb:
> info args
this = (IpAddress * const) 0xbec4f9c8
inaddr = 0xbec4f8c8 "EK250"
>>>>>>cb_gdb:
> whatis herrno
type = int
>>>>>>cb_gdb:
> output herrno
1>>>>>>cb_gdb:
> whatis lookupResult->h_addr_list
type = char **
>>>>>>cb_gdb:
> output lookupResult->h_addr_list
(char **) 0xbec4edd7>>>>>>cb_gdb:
> info locals
ipAddr = {s_addr = 0}
lookupResult = (hostent *) 0xbec4f608
buf = "\177\000\000\001\000\000\000\000\000\000\000\000\000000\000\000\000\000\000127.0.0.1\000EK250\000localhost.localdomain\000localhost\000\000 <repeats 1668 times>, "000\000\000\000Linux", '\0' <repeats 60 times>, "EK250", '\0' <repeats 60 times>, "2.6.19.2-EK20100211", '\0' <repeats 46 times>, "#1 PREEMPT Thu Feb 11 17:42:54"...
herrno = 1
lookup_buf = {h_name = 0xbec4ede9 "EK250", h_aliases = 0xbec4ee10, h_addrtype = 2, h_length = 4, h_addr_list = 0xbec4edd7}
ds = '\0' <repeats 46 times>, "(none)\000\000\000\000\000\000\000\000"
>>>>>>cb_gdb:
> info args
this = (IpAddress * const) 0xbec4f9c8
inaddr = 0xbec4f8c8 "EK250"
>>>>>>cb_gdb:
> whatis herrno
type = int
>>>>>>cb_gdb:
> output herrno
1>>>>>>cb_gdb:
> whatis lookupResult->h_addr_list
type = char **
>>>>>>cb_gdb:
> output lookupResult->h_addr_list
(char **) 0xbec4edd7>>>>>>cb_gdb:
> whatis lookupResult->h_addr_list[0]
type = char *
>>>>>>cb_gdb:
> output lookupResult->h_addr_list[0]
0xbe <Address 0xbe out of bounds>>>>>>>cb_gdb:
> next
/mnt/hda1/sorgenti_snmpv3_last_release/snmp++/src/address.cpp:893:23820:beg:0x11934
>>>>>>cb_gdb:
> info locals
ipAddr = {s_addr = 0}
lookupResult = (hostent *) 0xbec4f608
buf = "\177\000\000\001\000\000\000\000\000\000\000\000\000000\000\000\000\000\000127.0.0.1\000EK250\000localhost.localdomain\000localhost\000\000 <repeats 1668 times>, "000\000\000\000Linux", '\0' <repeats 60 times>, "EK250", '\0' <repeats 60 times>, "2.6.19.2-EK20100211", '\0' <repeats 46 times>, "#1 PREEMPT Thu Feb 11 17:42:54"...
herrno = 1
lookup_buf = {h_name = 0xbec4ede9 "EK250", h_aliases = 0xbec4ee10, h_addrtype = 2, h_length = 4, h_addr_list = 0xbec4edd7}
ds = '\0' <repeats 46 times>, "(none)\000\000\000\000\000\000\000\000"
>>>>>>cb_gdb:
> info args
this = (IpAddress * const) 0xbec4f9c8
inaddr = 0xbec4f8c8 "EK250"
>>>>>>cb_gdb:
> whatis herrno
type = int
>>>>>>cb_gdb:
> output herrno
1>>>>>>cb_gdb:
> whatis lookupResult->h_addr_list
type = char **
>>>>>>cb_gdb:
> output lookupResult->h_addr_list
(char **) 0xbec4edd7>>>>>>cb_gdb:
> whatis lookupResult->h_addr_list[0]
type = char *
>>>>>>cb_gdb:
> output lookupResult->h_addr_list[0]
0xbe <Address 0xbe out of bounds>>>>>>>cb_gdb:
> next
Program received signal SIGSEGV, Segmentation fault.
0x4026b84c in ?? ()
Obviously, if I comment
"memcpy((void *) &ipAddr, (void *) lookupResult->h_addr,
sizeof(in_addr));"
and replace "strcpy(ds, inet_ntoa(ipAddr));"
with "strcpy(ds, "127.0.0.1");"
then I don't get a segmentation fault.
Michele Marcon
Centro Ricerche
RPS SpA
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Tel. +39 0442 635811 - Fax. +39 0442 635934 - Mobile: +39 335 1233317
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E-mail: M.Marcon at riello-ups.com
Web: http://www.riello-ups.com
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-----Messaggio originale-----
Da: agentpp-bounces at agentpp.org [mailto:agentpp-bounces at agentpp.org] Per conto di Jochen Katz
Inviato: lunedì 21 febbraio 2011 21.36
A: agentpp at agentpp.org
Oggetto: Re: [AGENT++] R: R: pure virtual method called
Hi,
> I'm attaching the gdb output for the snmpTraps:
>
> #0 0x00011920 in IpAddress::parse_address (this=0xbeb499c8, inaddr=0xbeb498c8 "EK250") at address.cpp:881
this is the memcpy seen below. If this fails, the h_addr (which is
h_addr_list[0]) must be null. Please try the patch below.
Regards,
Jochen
--- address.cpp (Revision 1969)
+++ address.cpp (Arbeitskopie)
@@ -853,6 +853,12 @@
#ifdef SNMP_PP_IPv6
if (lookupResult->h_length == sizeof(in6_addr))
{
+ if (!lookupResult->h_addr_list[0])
+ {
+ debugprintf(1, "Error resolving host name");
+ return false;
+ }
+
in6_addr ipAddr;
memcpy((void *) &ipAddr, (void *) lookupResult->h_addr,
sizeof(in6_addr));
@@ -872,8 +878,13 @@
#endif // SNMP_PP_IPv6
if (lookupResult->h_length == sizeof(in_addr))
{
+ if (!lookupResult->h_addr_list[0])
+ {
+ debugprintf(1, "Error resolving host name");
+ return false;
+ }
+
in_addr ipAddr;
-
memcpy((void *) &ipAddr, (void *) lookupResult->h_addr,
sizeof(in_addr));
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