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Niklas Cassel 6045ab5fea binfmt_flat: do not stop relocating GOT entries prematurely on riscv
bFLT binaries are usually created using elf2flt.

The linker script used by elf2flt has defined the .data section like the
following for the last 19 years:

.data : {
	_sdata = . ;
	__data_start = . ;
	data_start = . ;
	*(.got.plt)
	*(.got)
	FILL(0) ;
	. = ALIGN(0x20) ;
	LONG(-1)
	. = ALIGN(0x20) ;
	...
}

It places the .got.plt input section before the .got input section.
The same is true for the default linker script (ld --verbose) on most
architectures except x86/x86-64.

The binfmt_flat loader should relocate all GOT entries until it encounters
a -1 (the LONG(-1) in the linker script).

The problem is that the .got.plt input section starts with a GOTPLT header
(which has size 16 bytes on elf64-riscv and 8 bytes on elf32-riscv), where
the first word is set to -1. See the binutils implementation for riscv [1].

This causes the binfmt_flat loader to stop relocating GOT entries
prematurely and thus causes the application to crash when running.

Fix this by skipping the whole GOTPLT header, since the whole GOTPLT header
is reserved for the dynamic linker.

The GOTPLT header will only be skipped for bFLT binaries with flag
FLAT_FLAG_GOTPIC set. This flag is unconditionally set by elf2flt if the
supplied ELF binary has the symbol _GLOBAL_OFFSET_TABLE_ defined.
ELF binaries without a .got input section should thus remain unaffected.

Tested on RISC-V Canaan Kendryte K210 and RISC-V QEMU nommu_virt_defconfig.

[1] https://sourceware.org/git/?p=binutils-gdb.git;a=blob;f=bfd/elfnn-riscv.c;hb=binutils-2_38#l3275

Cc: <stable@vger.kernel.org>
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Link: https://lore.kernel.org/r/20220414091018.896737-1-niklas.cassel@wdc.com
Fixed-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/lkml/202204182333.OIUOotK8-lkp@intel.com
Signed-off-by: Kees Cook <keescook@chromium.org>
History 2022-04-18 15:02:50 -07:00
arch Driver core changes for 5.18-rc2 2022-04-10 09:55:09 -10:00
block for-5.18/block-2022-04-01 2022-04-01 16:20:00 -07:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation linux-kselftest-kunit-fixes-5.18-rc2 2022-04-08 15:06:11 -10:00
drivers Serial driver fix for 5.18-rc2 2022-04-10 10:08:50 -10:00
fs binfmt_flat: do not stop relocating GOT entries prematurely on riscv 2022-04-18 15:02:50 -07:00
include Driver core changes for 5.18-rc2 2022-04-10 09:55:09 -10:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel - A couple of fixes to cgroup-related handling of perf events 2022-04-10 07:08:22 -10:00
lib Driver core changes for 5.18-rc2 2022-04-10 09:55:09 -10:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm - Allow the compiler to optimize away unused percpu accesses and change 2022-04-10 06:56:46 -10:00
net NFS client bugfixes for Linux 5.18 2022-04-08 07:39:17 -10:00
samples dma-mapping updates for Linux 5.18 2022-03-29 08:50:14 -07:00
scripts modpost: restore the warning message for missing symbol versions 2022-04-03 03:11:51 +09:00
security hardening updates for v5.18-rc1-fix1 2022-03-31 11:43:01 -07:00
sound sound fixes for 5.18-rc1 2022-04-01 10:32:46 -07:00
tools - Fix the MSI message data struct definition 2022-04-10 07:12:27 -10:00
usr Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
virt KVM: Remove dirty handling from gfn_to_pfn_cache completely 2022-04-02 05:34:41 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Vasily Averin's email address 2022-04-08 14:20:36 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS v5.18 first rc pull request 2022-04-08 18:29:02 -10:00
Makefile Linux 5.18-rc2 2022-04-10 14:21:36 -10:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.