On Wed, Dec 19, 2007 at 11:57:28AM -0500, Daniel Jacobowitz wrote:
>MontaVista noticed that when their kernels were configured to trap
>on unaligned access gethostbyname_r could mysteriously crash. I
>tracked this down to an unaligned buffer being passed to
>gethostbyname_r from some other part of uClibc (afraid I don't
>remember where from any more). We have to pad the beginning of
>the buffer to a pointer alignment before we store pointers in
>it.
>
>Is this patch OK?
>
>--
>Daniel Jacobowitz
>CodeSourcery
>
>--- libc/inet/resolv.c (revision 189757)
>+++ libc/inet/resolv.c (local)
>@@ -1534,6 +1534,15 @@ int attribute_hidden __read_etc_hosts_r(
> char *cp, **alias;
> int aliases, i, ret = HOST_NOT_FOUND;
>
>+ /* Align to at least the size of a char * so we can put
>+ pointers in it. */
>+ i = (unsigned long) buf % sizeof(char *);
>+ i = (sizeof(char *) - i) % sizeof(char *);
>+ if (buflen < i)
>+ return ERANGE;
>+ buf+=i;
>+ buflen-=i;
>+
> if (buflen < sizeof(char *)*(ALIAS_DIM))
> return ERANGE;
> alias = (char **)buf;
>@@ -2030,6 +2039,16 @@ int gethostbyname_r(const char * name,
> DPRINTF("Nothing found in /etc/hosts\n");
>
> *h_errnop = NETDB_INTERNAL;
>+
>+ /* Align to at least the size of a char * so we can put
>+ pointers in it. */
>+ i = (unsigned long) buf % sizeof(char *);
>+ i = (sizeof(char *) - i) % sizeof(char *);
>+ if (buflen < i)
>+ return ERANGE;
>+ buf+=i;
>+ buflen-=i;
>+
This sounds OK to me. Please install it along a testcase if you tested it and
found it to be good on all platforms in most common configurations with
no regressions.
thanks..
> if (buflen < sizeof(*in))
> return ERANGE;
> in = (struct in_addr*)buf;
_______________________________________________
uClibc mailing list
uClibc@uclibc.org
http://busybox.net/cgi-bin/mailman/listinfo/uclibc
