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3758a6c74e
In ex_handler_load_unaligned_zeropad() we erroneously extract the data and
addr register indices from ex->type rather than ex->data. As ex->type will
contain EX_TYPE_LOAD_UNALIGNED_ZEROPAD (i.e. 4):
* We'll always treat X0 as the address register, since EX_DATA_REG_ADDR is
extracted from bits [9:5]. Thus, we may attempt to dereference an
arbitrary address as X0 may hold an arbitrary value.
* We'll always treat X4 as the data register, since EX_DATA_REG_DATA is
extracted from bits [4:0]. Thus we will corrupt X4 and cause arbitrary
behaviour within load_unaligned_zeropad() and its caller.
Fix this by extracting both values from ex->data as originally intended.
On an MTE-enabled QEMU image we are hitting the following crash:
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Call trace:
fixup_exception+0xc4/0x108
__do_kernel_fault+0x3c/0x268
do_tag_check_fault+0x3c/0x104
do_mem_abort+0x44/0xf4
el1_abort+0x40/0x64
el1h_64_sync_handler+0x60/0xa0
el1h_64_sync+0x7c/0x80
link_path_walk+0x150/0x344
path_openat+0xa0/0x7dc
do_filp_open+0xb8/0x168
do_sys_openat2+0x88/0x17c
__arm64_sys_openat+0x74/0xa0
invoke_syscall+0x48/0x148
el0_svc_common+0xb8/0xf8
do_el0_svc+0x28/0x88
el0_svc+0x24/0x84
el0t_64_sync_handler+0x88/0xec
el0t_64_sync+0x1b4/0x1b8
Code: f8695a69 71007d1f 540000e0 927df12a (f940014a)
Fixes:
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|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.