From: Helge Deller deller@gmx.de
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 --- 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