[exim-dev] [Bug 619] New: Core dumps on NULL hosts->h_name

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http://bugs.exim.org/show_bug.cgi?id=619
           Summary: Core dumps on NULL hosts->h_name
           Product: Exim
           Version: 4.68
          Platform: x86
        OS/Version: Solaris
            Status: NEW
          Severity: bug
          Priority: medium
         Component: General execution
        AssignedTo: ph10@???
        ReportedBy: alex.kiernan@???
                CC: exim-dev@???

Created an attachment (id=214)
--> (http://bugs.exim.org/attachment.cgi?id=214)
Fix NULL pointer dereference in host_name_lookup_byaddr

On Solaris 10 x86 we're seeing NULL pointers in h_name on return from
gethostbyaddr which is causing coredumps around host.c:1505:

if (hosts->h_name[0] == 0 || hosts->h_name[0] == '.')

Can be demonstrated using this test program:

#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <stdio.h>

int main(void)
{
struct in_addr addr;
struct hostent *hosts;

addr.s_addr = inet_addr("91.186.12.143");
hosts = gethostbyaddr(&addr, sizeof(addr), AF_INET);
printf("hosts=%lx\n", hosts);
printf("hosts->h_name=%lx\n", hosts->h_name);
printf("hosts->h_name='%s'\n", hosts->h_name);
}

gives:

hosts=80609b4
hosts->h_name=0
Segmentation Fault (core dumped)

Suggested patch attached.


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