commit 98400ad75e95860e9a10ec78b0b90ab66184a2ce upstream.
This reverts commit 279917e27edc293eb645a25428c6ab3f3bca3f86.
With the CONFIG_HARDENED_USERCOPY option enabled, this patch triggers
kernel bugs at runtime:
usercopy: Kernel memory overwrite attempt detected to kernel text (offset 2084839, size 6)!
kernel BUG at mm/usercopy.c:99!
Backtrace:
IAOQ[0]: usercopy_abort+0xc4/0xe8
[<00000000406ed1c8>] __check_object_size+0x174/0x238
[<00000000407086d4>] copy_strings.isra.0+0x3e8/0x708
[<0000000040709a20>] do_execveat_common.isra.0+0x1bc/0x328
[<000000004070b760>] compat_sys_execve+0x7c/0xb8
[<0000000040303eb8>] syscall_exit+0x0/0x14
The problem is, that we have an init section of at least 2MB size which
starts at _stext and is freed after bootup.
If then later some kernel data is (temporarily) stored in this free
memory, check_kernel_text_object() will trigger a bug since the data
appears to be inside the kernel text (>=_stext) area:
if (overlaps(ptr, len, _stext, _etext))
usercopy_abort("kernel text");
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: stable@kernel.org # 5.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
c03ad97293