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s390/boot: fix mem_detect extended area allocation

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Allocation of mem_detect extended area was not considered neither
in commit 9641b8cc73 ("s390/ipl: read IPL report at early boot")
nor in commit b2d24b97b2 ("s390/kernel: add support for kernel address
space layout randomization (KASLR)"). As a result mem_detect extended
theoretically may overlap with ipl report or randomized kernel image
position. But as mem_detect code will allocate extended area only
upon exceeding 255 online regions (which should alternate with offline
memory regions) it is not seen in practice.

To make sure mem_detect extended area does not overlap with ipl report
or randomized kernel position extend usage of "safe_addr". Make initrd
handling and mem_detect extended area allocation code move it further
right and make KASLR takes in into consideration as well.

Fixes: 9641b8cc73 ("s390/ipl: read IPL report at early boot")
Fixes: b2d24b97b2 ("s390/kernel: add support for kernel address space layout randomization (KASLR)")
Reviewed-by: Alexander Gordeev <agordeev@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
This commit is contained in:
Vasily Gorbik 2023-01-23 12:49:47 +01:00 committed by Heiko Carstens
parent eb33f9eb30
commit 22476f47b6
4 changed files with 31 additions and 52 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/s390/boot/boot.h
View File

@ -33,10 +33,10 @@ struct vmlinux_info {
};
void startup_kernel(void);
unsigned long detect_memory(void);
unsigned long detect_memory(unsigned long *safe_addr);
bool is_ipl_block_dump(void);
void store_ipl_parmblock(void);
unsigned long read_ipl_report(unsigned long safe_offset);
unsigned long read_ipl_report(unsigned long safe_addr);
void setup_boot_command_line(void);
void parse_boot_command_line(void);
void verify_facilities(void);

6
arch/s390/boot/kaslr.c
View File

@ -174,7 +174,6 @@ unsigned long get_random_base(unsigned long safe_addr)
{
unsigned long memory_limit = get_mem_detect_end();
unsigned long base_pos, max_pos, kernel_size;
unsigned long kasan_needs;
int i;
memory_limit = min(memory_limit, ident_map_size);
@ -186,12 +185,7 @@ unsigned long get_random_base(unsigned long safe_addr)
*/
memory_limit -= kasan_estimate_memory_needs(memory_limit);
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_data.start && initrd_data.size) {
if (safe_addr < initrd_data.start + initrd_data.size)
safe_addr = initrd_data.start + initrd_data.size;
}
safe_addr = ALIGN(safe_addr, THREAD_SIZE);
kernel_size = vmlinux.image_size + vmlinux.bss_size;
if (safe_addr + kernel_size > memory_limit)
return 0;

52
arch/s390/boot/mem_detect.c
View File

@ -16,29 +16,10 @@ struct mem_detect_info __bootdata(mem_detect);
#define ENTRIES_EXTENDED_MAX \
(256 * (1020 / 2) * sizeof(struct mem_detect_block))
/*
* To avoid corrupting old kernel memory during dump, find lowest memory
* chunk possible either right after the kernel end (decompressed kernel) or
* after initrd (if it is present and there is no hole between the kernel end
* and initrd)
*/
static void *mem_detect_alloc_extended(void)
{
unsigned long offset = ALIGN(mem_safe_offset(), sizeof(u64));
if (IS_ENABLED(CONFIG_BLK_DEV_INITRD) && initrd_data.start && initrd_data.size &&
initrd_data.start < offset + ENTRIES_EXTENDED_MAX)
offset = ALIGN(initrd_data.start + initrd_data.size, sizeof(u64));
return (void *)offset;
}
static struct mem_detect_block *__get_mem_detect_block_ptr(u32 n)
{
if (n < MEM_INLINED_ENTRIES)
return &mem_detect.entries[n];
if (unlikely(!mem_detect.entries_extended))
mem_detect.entries_extended = mem_detect_alloc_extended();
return &mem_detect.entries_extended[n - MEM_INLINED_ENTRIES];
}
@ -147,7 +128,7 @@ static int tprot(unsigned long addr)
return rc;
}
static void search_mem_end(void)
static unsigned long search_mem_end(void)
{
unsigned long range = 1 << (MAX_PHYSMEM_BITS - 20); /* in 1MB blocks */
unsigned long offset = 0;
@ -159,33 +140,34 @@ static void search_mem_end(void)
if (!tprot(pivot << 20))
offset = pivot;
}
add_mem_detect_block(0, (offset + 1) << 20);
return (offset + 1) << 20;
}
unsigned long detect_memory(void)
unsigned long detect_memory(unsigned long *safe_addr)
{
unsigned long max_physmem_end = 0;
sclp_early_get_memsize(&max_physmem_end);
mem_detect.entries_extended = (struct mem_detect_block *)ALIGN(*safe_addr, sizeof(u64));
if (!sclp_early_read_storage_info()) {
mem_detect.info_source = MEM_DETECT_SCLP_STOR_INFO;
return max_physmem_end;
}
if (!diag260()) {
} else if (!diag260()) {
mem_detect.info_source = MEM_DETECT_DIAG260;
return max_physmem_end ?: get_mem_detect_end();
}
if (max_physmem_end) {
max_physmem_end = max_physmem_end ?: get_mem_detect_end();
} else if (max_physmem_end) {
add_mem_detect_block(0, max_physmem_end);
mem_detect.info_source = MEM_DETECT_SCLP_READ_INFO;
return max_physmem_end;
} else {
max_physmem_end = search_mem_end();
add_mem_detect_block(0, max_physmem_end);
mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
}
search_mem_end();
mem_detect.info_source = MEM_DETECT_BIN_SEARCH;
return get_mem_detect_end();
if (mem_detect.count > MEM_INLINED_ENTRIES) {
*safe_addr += (mem_detect.count - MEM_INLINED_ENTRIES) *
sizeof(struct mem_detect_block);
}
return max_physmem_end;
}

21
arch/s390/boot/startup.c
View File

@ -76,16 +76,17 @@ unsigned long mem_safe_offset(void)
}
#endif
static void rescue_initrd(unsigned long addr)
static unsigned long rescue_initrd(unsigned long safe_addr)
{
if (!IS_ENABLED(CONFIG_BLK_DEV_INITRD))
return;
return safe_addr;
if (!initrd_data.start || !initrd_data.size)
return;
if (addr <= initrd_data.start)
return;
memmove((void *)addr, (void *)initrd_data.start, initrd_data.size);
initrd_data.start = addr;
return safe_addr;
if (initrd_data.start < safe_addr) {
memmove((void *)safe_addr, (void *)initrd_data.start, initrd_data.size);
initrd_data.start = safe_addr;
}
return initrd_data.start + initrd_data.size;
}
static void copy_bootdata(void)
@ -275,6 +276,7 @@ static unsigned long reserve_amode31(unsigned long safe_addr)
void startup_kernel(void)
{
unsigned long max_physmem_end;
unsigned long random_lma;
unsigned long safe_addr;
unsigned long asce_limit;
@ -294,12 +296,13 @@ void startup_kernel(void)
safe_addr = reserve_amode31(safe_addr);
safe_addr = read_ipl_report(safe_addr);
uv_query_info();
rescue_initrd(safe_addr);
safe_addr = rescue_initrd(safe_addr);
sclp_early_read_info();
setup_boot_command_line();
parse_boot_command_line();
sanitize_prot_virt_host();
setup_ident_map_size(detect_memory());
max_physmem_end = detect_memory(&safe_addr);
setup_ident_map_size(max_physmem_end);
setup_vmalloc_size();
asce_limit = setup_kernel_memory_layout();