aec3b1f7d7
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> |
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.. | ||
arch | ||
bin | ||
configs | ||
crypto | ||
curses | ||
drivers | ||
gdb | ||
include | ||
libc | ||
libcbfs | ||
liblz4 | ||
liblzma | ||
libpci | ||
sample | ||
tests | ||
Doxyfile | ||
Kconfig | ||
LICENSE_GPL | ||
LICENSES | ||
Makefile | ||
Makefile.inc | ||
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.