From: Helge Deller <deller@xxxxxx>
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@xxxxxx>
Cc: stable@xxxxxxxxxx # 5.4+
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/parisc/kernel/vmlinux.lds.S | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/arch/parisc/kernel/vmlinux.lds.S
+++ b/arch/parisc/kernel/vmlinux.lds.S
@@ -57,8 +57,6 @@ SECTIONS
{
. = KERNEL_BINARY_TEXT_START;
- _stext = .; /* start of kernel text, includes init code & data */
-
__init_begin = .;
HEAD_TEXT_SECTION
MLONGCALL_DISCARD(INIT_TEXT_SECTION(8))
@@ -82,6 +80,7 @@ SECTIONS
/* freed after init ends here */
_text = .; /* Text and read-only data */
+ _stext = .;
MLONGCALL_KEEP(INIT_TEXT_SECTION(8))
.text ALIGN(PAGE_SIZE) : {
TEXT_TEXT
