[U-Boot] [PATCH v5 0/4] Buffer overruns in printf

Simon Glass sjg at chromium.org
Wed Oct 26 01:42:40 CEST 2011


The printf family of functions in U-Boot cannot deal with a situation where
the caller provides a buffer which turns out to be too small for the format
string. This can result in buffer overflows, stack overflows and other bad
behavior.

This patch series tidies this up in the common vsprintf.c code.

You can find a discussion of the Linux / U-Boot licensing issues here:

http://patchwork.ozlabs.org/patch/116161/

Code Size Impact
----------------

(From Simon Glass <sjg at chromium.org>)
With my ARMv7 compiler (gcc-4.4.3_cos_gg_53174) the code size increase is
312 bytes, about 10% increase to code size vsprintf.o.

With the CONFIG_SYS_NO_VSNPRINT option defined, the code size impact
is 4 bytes.


Changes in v2:
- Use sizeof(printbuffer) instead of CONFIG_SYS_PBSIZE
- Drop patch which changes network code to use snprintf()

Changes in v3:
- Move prototypes from common.h to vsprintf.h
- Add CONFIG_SYS_VSNPRINT option to enable vsnprintf() functions
- Update README with CONFIG_SYS_VSNPRINT docs
- Use ADDCH macro to support checking/not checking end pointer
- Move function documentation into header file

Changes in v4:
- Add these changes in unless CONFIG_NO_SYS_VSNPRINT is defined
- Reduce code size overhead if disabled to only 4 bytes on ARM
- Remove the ugly #ifdef patch from series since it only saves 4 bytes

Changes in v5:
- Define INT_MAX locally within vsprintf.c
- Drop limits.h as it is used in only two places in U-Boot

Simon Glass (2):
  Move vsprintf functions into their own header
  vsprintf: Move function documentation into header file

Sonny Rao (2):
  Add safe vsnprintf and snprintf library functions
  Make printf and vprintf safe from buffer overruns

 README             |    7 ++
 common/console.c   |   10 +-
 include/common.h   |   10 +--
 include/vsprintf.h |  180 +++++++++++++++++++++++++++++++++++++++
 lib/vsprintf.c     |  237 ++++++++++++++++++++++++++++++++-------------------
 5 files changed, 342 insertions(+), 102 deletions(-)
 create mode 100644 include/vsprintf.h

-- 
1.7.3.1



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