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Revision 89a8640279f8bb78aaf778d1fc5c4a6778f18064 authored by David Howells on 30 October 2009, 13:13:26 UTC, committed by Linus Torvalds on 31 October 2009, 19:11:37 UTC 
NOMMU: Don't pass NULL pointers to fput() in do_mmap_pgoff()
 
Don't pass NULL pointers to fput() in the error handling paths of the NOMMU
do_mmap_pgoff() as it can't handle it.

The following can be used as a test program:

	int main() { static long long a[1024 * 1024 * 20] = { 0 }; return a;}

Without the patch, the code oopses in atomic_long_dec_and_test() as called by
fput() after the kernel complains that it can't allocate that big a chunk of
memory.  With the patch, the kernel just complains about the allocation size
and then the program segfaults during execve() as execve() can't complete the
allocation of all the new ELF program segments.

Reported-by: Robin Getz <rgetz@blackfin.uclinux.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent 2e2ec95
Raw File
headers_install.txt 
Exporting kernel headers for use by userspace
=============================================

The "make headers_install" command exports the kernel's header files in a
form suitable for use by userspace programs.

The linux kernel's exported header files describe the API for user space
programs attempting to use kernel services.  These kernel header files are
used by the system's C library (such as glibc or uClibc) to define available
system calls, as well as constants and structures to be used with these
system calls.  The C library's header files include the kernel header files
from the "linux" subdirectory.  The system's libc headers are usually
installed at the default location /usr/include and the kernel headers in
subdirectories under that (most notably /usr/include/linux and
/usr/include/asm).

Kernel headers are backwards compatible, but not forwards compatible.  This
means that a program built against a C library using older kernel headers
should run on a newer kernel (although it may not have access to new
features), but a program built against newer kernel headers may not work on an
older kernel.

The "make headers_install" command can be run in the top level directory of the
kernel source code (or using a standard out-of-tree build).  It takes two
optional arguments:

  make headers_install ARCH=i386 INSTALL_HDR_PATH=/usr/include

ARCH indicates which architecture to produce headers for, and defaults to the
current architecture.  The linux/asm directory of the exported kernel headers
is platform-specific, to see a complete list of supported architectures use
the command:

  ls -d include/asm-* | sed 's/.*-//'

INSTALL_HDR_PATH indicates where to install the headers.  It defaults to
"./usr/include".

The command "make headers_install_all" exports headers for all architectures
simultaneously.  (This is mostly of interest to distribution maintainers,
who create an architecture-independent tarball from the resulting include
directory.)  Remember to provide the appropriate linux/asm directory via "mv"
or "ln -s" before building a C library with headers exported this way.

The kernel header export infrastructure is maintained by David Woodhouse
<dwmw2@infradead.org>.
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