1 files changed, 22 insertions, 21 deletions

diff --git a/src/lib/libc/stdlib/alloca.3 b/src/lib/libc/stdlib/alloca.3
index dcb97ab11c..d7fddb04c2 100644
--- a/src/lib/libc/stdlib/alloca.3
+++ b/src/lib/libc/stdlib/alloca.3
@@ -9,11 +9,7 @@
 .\" 2. Redistributions in binary form must reproduce the above copyright
 .\"    notice, this list of conditions and the following disclaimer in the
 .\"    documentation and/or other materials provided with the distribution.
-.\" 3. All advertising materials mentioning features or use of this software
-.\"    must display the following acknowledgement:
-.\"     This product includes software developed by the University of
-.\"     California, Berkeley and its contributors.
-.\" 4. Neither the name of the University nor the names of its contributors
+.\" 3. Neither the name of the University nor the names of its contributors
 .\"    may be used to endorse or promote products derived from this software
 .\"    without specific prior written permission.
 .\"
@@ -29,12 +25,11 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.\"     from: @(#)alloca.3      5.1 (Berkeley) 5/2/91
-.\"     $Id: alloca.3,v 1.1.1.1 1995/10/18 08:42:16 deraadt Exp $
+.\"     $OpenBSD: alloca.3,v 1.11 2007/05/31 19:19:31 jmc Exp $
 .\"
-.Dd May 2, 1991
+.Dd $Mdocdate: May 31 2007 $
 .Dt ALLOCA 3
-.Os BSD 4
+.Os
 .Sh NAME
 .Nm alloca
 .Nd memory allocator
@@ -45,35 +40,41 @@
 .Sh DESCRIPTION
 The
 .Fn alloca
-function
-allocates 
+function allocates
 .Fa size
 bytes of space in the stack frame of the caller.
-This temporary space is automatically freed on
-return.
+This temporary space is automatically freed on return.
 .Sh RETURN VALUES
 The
 .Fn alloca
 function returns a pointer to the beginning of the allocated space.
-If the allocation failed, a
-.Dv NULL
-pointer is returned.
 .Sh SEE ALSO
+.Xr pagesize 1 ,
 .Xr brk 2 ,
-.Xr pagesize 2
 .Xr calloc 3 ,
 .Xr malloc 3 ,
-.Xr realloc 3 ,
+.Xr realloc 3
 .Sh BUGS
 The
 .Fn alloca
-function
-is machine dependent; its use is discouraged.
+function is machine dependent; its use is discouraged.
 .\" .Sh HISTORY
 .\" The
 .\" .Fn alloca
 .\" function appeared in
 .\" .Bx ?? .
-.\" The function appeared in 32v, pwb and pwb.2 and in 3bsd 4bsd 
+.\" The function appeared in 32v, pwb and pwb.2 and in 3bsd 4bsd
 .\" The first man page (or link to a man page that I can find at the
 .\" moment is 4.3...
+.Pp
+The
+.Fn alloca
+function is slightly unsafe because it cannot ensure that the pointer
+returned points to a valid and usable block of memory.
+The allocation made may exceed the bounds of the stack, or even go
+further into other objects in memory, and
+.Fn alloca
+cannot determine such an error.
+Avoid
+.Fn alloca
+with large unbounded allocations.