Merge remote-tracking branch 'origin/master'

README.md

@@ -1,3 +1,8 @@
+# BETA SOFTWARE
+
+This is barely a beta.  There are currently no versioned releases, only `master`.  I push to master with impunity.  There are no tests.  If anything works at all, consider yourself lucky.
+
+Feature contributions and bugfixes are both very welcome :)
 
 # pwndbg
 
@@ -12,7 +17,7 @@ Best supported on Ubuntu 14.04 with default `gdb` or `gdb-multiarch` (e.g. with
 ## Installation
 
 1. Clone the repo: `git clone https://github.com/zachriggle/pwndbg`
-2. Add to `~/.gdbinit`: `source ~/pwndbg/gdbinit.py`
+2. Add to `~/.gdbinit`: `echo "source $PWD/pwndbg/gdbinit.py" >> ~/.gdbinit`
 
 ### Prerequisites
 
@@ -21,8 +26,8 @@ Best supported on Ubuntu 14.04 with default `gdb` or `gdb-multiarch` (e.g. with
 Currently this is only available via a source build.
 
 1. Clone the repo: `git clone https://github.com/aquynh/capstone`
-2. Select the `next` branch: `git checkout -t origin/next`
-3. Build and install libcapstone: `sudo make.sh install`
+2. Select the `next` branch: `cd capstone && git checkout -t origin/next`
+3. Build and install libcapstone: `sudo ./make.sh install`
 4. Build and install Python bindings: `cd bindings/python && python setup.py install`
 
 #### pycparser

pwndbg/stack.py

@@ -54,17 +54,18 @@ def update():
     for its stack.
     """
     curr_thread = gdb.selected_thread()
-
     try:
         for thread in gdb.selected_inferior().threads():
             thread.switch()
             sp = pwndbg.regs.sp
 
+            sp_low = sp & ~(0xfff)
+
             # If we don't already know about this thread, create
             # a new Page mapping for it.
             page = stacks.get(thread.ptid, None)
             if page is None:
-                start = pwndbg.memory.find_lower_boundary(sp)
+                start = sp_low
                 stop  = find_upper_stack_boundary(sp)
                 page  = pwndbg.memory.Page(start, stop-start, 6 if not is_executable() else 7, 0, '[stack]')
                 stacks[thread.ptid] = page
@@ -73,8 +74,8 @@ def update():
                 page.objfile = '[stack]'
 
             # If we *DO* already know about this thread, just
-            # update the lower boundary.
-            low = pwndbg.memory.find_lower_boundary(page.vaddr)
+            # update the lower boundary if it got any lower.
+            low = min(page.vaddr, sp_low)
             if low != page.vaddr:
                 page.memsz  += (page.vaddr - low)
                 page.vaddr   = low