coreboot-kgpe-d16/payloads/libpayload
Yu-Ping Wu aec3b1f7d7 libpayload: malloc: Fix realloc for overlapping buffers
The current realloc() works by freeing the origin buffer, allocating a
new one, and copying the data over. It's true that free() won't touch
the actual memory. However, the alloc() following it will potentially
modify the memory that belongs to the old buffer in order to create a
new free block (right after the newly allocated block). This causes 8
bytes (HDRSIZE) to be overwritten before being copied to the new buffer.

To fix the problem, we must create the header of the new free block
after the data is copied. In this patch, the content of alloc() is split
into two functions:

1. find_free_block(): Find a free block with large enough size, without
   touching the memory
2. use_block(): Update the header of the newly allocated block, and
   create the header of the new free block right after it

Then, inside realloc(), call memmove() call right after
find_free_block() while before use_block().

BUG=b:165439970
TEST=emerge-puff libpayload
TEST=Puff boots
TEST=Verified realloc() correctly copied data when buffers overlapped

Change-Id: I9418320a26820909144890300ddfb09ec2570f43
Signed-off-by: Yu-Ping Wu <yupingso@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/45284
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>
2020-09-13 13:40:11 +00:00
..
arch libpayload: Cache physical location of CBMEM entries 2020-08-24 09:13:30 +00:00
bin
configs libpayload/defconfig: Set default heap size to 1MiB 2020-08-17 06:10:49 +00:00
crypto
curses payloads/libpayload/curses/menu/eti.h: Remove unneeded whitespaces 2020-07-25 01:25:16 +00:00
drivers libpayload/xhci: Fix Slot State field width definition 2020-09-04 19:13:31 +00:00
gdb
include libpayload: cbgfx: Support buffered I/O 2020-08-28 21:40:58 +00:00
libc libpayload: malloc: Fix realloc for overlapping buffers 2020-09-13 13:40:11 +00:00
libcbfs
liblz4
liblzma
libpci
sample
tests
Doxyfile
Kconfig libpayload: cbgfx: Replace bilinear resampling with Lanczos 2020-07-09 00:32:17 +00:00
LICENSES
LICENSE_GPL
Makefile
Makefile.inc
README

README

-------------------------------------------------------------------------------
libpayload README
-------------------------------------------------------------------------------

libpayload is a minimal library to support standalone payloads
that can be booted with firmware like coreboot. It handles the setup
code, and provides common C library symbols such as malloc() and printf().

Note: This is _not_ a standard library for use with an operating system,
rather it's only useful for coreboot payload development!
See https://www.coreboot.org for details on coreboot.


Installation
------------

 $ git clone https://review.coreboot.org/coreboot.git

 $ cd coreboot/payloads/libpayload

 $ make menuconfig

 $ make

 $ make install (optional, will install into ./install per default)

On x86 systems, libpayload will always be 32-bit even if your host OS runs
in 64-bit, so you might have to install the 32-bit libgcc version.
On Debian systems you'd do 'apt-get install gcc-multilib' for example.

Run 'make distclean' before switching boards. This command will remove
your current .config file, so you need 'make menuconfig' again or
'make defconfig' in order to set up configuration. Default configuration
is based on 'configs/defconfig'. See the configs/ directory for examples
of configuration.


Usage
-----

Here's an example of a very simple payload (hello.c) and how to build it:

 #include <libpayload.h>

 int main(void)
 {
     printf("Hello, world!\n");
     return 0;
 }

Building the payload using the 'lpgcc' compiler wrapper:

 $ lpgcc -o hello.elf hello.c

Please see the sample/ directory for details.


Website and Mailing List
------------------------

The main website is https://www.coreboot.org/Libpayload.

For additional information, patches, and discussions, please join the
coreboot mailing list at https://www.coreboot.org/Mailinglist, where most
libpayload developers are subscribed.


Copyright and License
---------------------

See LICENSES.