commit 630f4cc3aa019ede55976ea561f1a7af2f068639

Author: Szabolcs Nagy <szabolcs.nagy@arm.com>

Date:   Wed Dec 6 13:05:50 2017 +0000

    [BZ #22637] Fix stack guard size accounting

    Previously if user requested S stack and G guard when creating a

    thread, the total mapping was S and the actual available stack was

    S - G - static_tls, which is not what the user requested.

    This patch fixes the guard size accounting by pretending the user

    requested S+G stack.  This way all later logic works out except

    when reporting the user requested stack size (pthread_getattr_np)

    or when computing the minimal stack size (__pthread_get_minstack).

    Normally this will increase thread stack allocations by one page.

    TLS accounting is not affected, that will require a separate fix.

            [BZ #22637]

            * nptl/descr.h (stackblock, stackblock_size): Update comments.

            * nptl/allocatestack.c (allocate_stack): Add guardsize to stacksize.

            * nptl/nptl-init.c (__pthread_get_minstack): Remove guardsize from

            stacksize.

            * nptl/pthread_getattr_np.c (pthread_getattr_np): Likewise.

Index: glibc-2.17-c758a686/nptl/allocatestack.c

===================================================================

--- glibc-2.17-c758a686.orig/nptl/allocatestack.c

+++ glibc-2.17-c758a686/nptl/allocatestack.c

@@ -470,6 +470,10 @@ allocate_stack (const struct pthread_att

       /* Make sure the size of the stack is enough for the guard and

 	 eventually the thread descriptor.  */

       guardsize = (attr->guardsize + pagesize_m1) & ~pagesize_m1;

+      if (guardsize < attr->guardsize || size + guardsize < guardsize)

+	/* Arithmetic overflow.  */

+	return EINVAL;

+      size += guardsize;

       if (__builtin_expect (size < ((guardsize + __static_tls_size

 				     + MINIMAL_REST_STACK + pagesize_m1)

 				    & ~pagesize_m1),

Index: glibc-2.17-c758a686/nptl/descr.h

===================================================================

--- glibc-2.17-c758a686.orig/nptl/descr.h

+++ glibc-2.17-c758a686/nptl/descr.h

@@ -366,9 +366,9 @@ struct pthread

   struct _Unwind_Exception exc;

 #endif

-  /* If nonzero pointer to area allocated for the stack and its

-     size.  */

+  /* If nonzero, pointer to the area allocated for the stack and guard. */

   void *stackblock;

+  /* Size of the stackblock area including the guard.  */

   size_t stackblock_size;

   /* Size of the included guard area.  */

   size_t guardsize;

Index: glibc-2.17-c758a686/nptl/nptl-init.c

===================================================================

--- glibc-2.17-c758a686.orig/nptl/nptl-init.c

+++ glibc-2.17-c758a686/nptl/nptl-init.c

@@ -500,8 +500,5 @@ strong_alias (__pthread_initialize_minim

 size_t

 __pthread_get_minstack (const pthread_attr_t *attr)

 {

-  struct pthread_attr *iattr = (struct pthread_attr *) attr;

-

-  return (GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN

-	  + iattr->guardsize);

+  return GLRO(dl_pagesize) + __static_tls_size + PTHREAD_STACK_MIN;

 }

Index: glibc-2.17-c758a686/nptl/pthread_getattr_np.c

===================================================================

--- glibc-2.17-c758a686.orig/nptl/pthread_getattr_np.c

+++ glibc-2.17-c758a686/nptl/pthread_getattr_np.c

@@ -59,8 +59,11 @@ pthread_getattr_np (thread_id, attr)

   /* The sizes are subject to alignment.  */

   if (__builtin_expect (thread->stackblock != NULL, 1))

     {

-      iattr->stacksize = thread->stackblock_size;

-      iattr->stackaddr = (char *) thread->stackblock + iattr->stacksize;

+      /* The stack size reported to the user should not include the

+	 guard size.  */

+      iattr->stacksize = thread->stackblock_size - thread->guardsize;

+      iattr->stackaddr = (char *) thread->stackblock

+       			 + thread->stackblock_size;

     }

   else

     {