From 2ed8b509753a0454b52b2d72e982265472c8d861 Mon Sep 17 00:00:00 2001 From: Alexander Gordeev Date: Fri, 26 May 2023 14:30:29 +0200 Subject: [PATCH] s390/kasan: fix insecure W+X mapping warning Since commit 3b5c3f000c2e ("s390/kasan: move shadow mapping to decompressor") the decompressor establishes mappings for the shadow memory and sets initial protection attributes to RWX. The decompressed kernel resets protection to RW+NX later on. In case a shadow memory range is not aligned on page boundary (e.g. as result of mem= kernel command line parameter use), the "Checked W+X mappings: FAILED, 1 W+X pages found" warning hits. Reported-by: Vasily Gorbik Fixes: 557b19709da9 ("s390/kasan: move shadow mapping to decompressor") Reviewed-by: Vasily Gorbik Signed-off-by: Alexander Gordeev --- arch/s390/mm/vmem.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/arch/s390/mm/vmem.c b/arch/s390/mm/vmem.c index 5b22c6e..b9dcb4a 100644 --- a/arch/s390/mm/vmem.c +++ b/arch/s390/mm/vmem.c @@ -667,7 +667,15 @@ static void __init memblock_region_swap(void *a, void *b, int size) #ifdef CONFIG_KASAN #define __sha(x) ((unsigned long)kasan_mem_to_shadow((void *)x)) + +static inline int set_memory_kasan(unsigned long start, unsigned long end) +{ + start = PAGE_ALIGN_DOWN(__sha(start)); + end = PAGE_ALIGN(__sha(end)); + return set_memory_rwnx(start, (end - start) >> PAGE_SHIFT); +} #endif + /* * map whole physical memory to virtual memory (identity mapping) * we reserve enough space in the vmalloc area for vmemmap to hotplug @@ -737,10 +745,8 @@ void __init vmem_map_init(void) } #ifdef CONFIG_KASAN - for_each_mem_range(i, &base, &end) { - set_memory_rwnx(__sha(base), - (__sha(end) - __sha(base)) >> PAGE_SHIFT); - } + for_each_mem_range(i, &base, &end) + set_memory_kasan(base, end); #endif set_memory_rox((unsigned long)_stext, (unsigned long)(_etext - _stext) >> PAGE_SHIFT); -- 2.7.4