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x86/boot: Save fields explicitly, zero out everything else

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Recent gcc compilers (gcc 9.1) generate warnings about an out of bounds
memset, if the memset goes accross several fields of a struct. This
generated a couple of warnings on x86_64 builds in sanitize_boot_params().

Fix this by explicitly saving the fields in struct boot_params
that are intended to be preserved, and zeroing all the rest.

[ tglx: Tagged for stable as it breaks the warning free build there as well ]

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: H. Peter Anvin <hpa@zytor.com>
Signed-off-by: John Hubbard <jhubbard@nvidia.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190731054627.5627-2-jhubbard@nvidia.com
This commit is contained in:
John Hubbard 2019-07-30 22:46:27 -07:00 committed by Thomas Gleixner
parent 5ed1c835ed
commit a90118c445
1 changed files with 48 additions and 15 deletions
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63
arch/x86/include/asm/bootparam_utils.h
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@ -18,6 +18,20 @@
* Note: efi_info is commonly left uninitialized, but that field has a * Note: efi_info is commonly left uninitialized, but that field has a
* private magic, so it is better to leave it unchanged. * private magic, so it is better to leave it unchanged.
*/ */
#define sizeof_mbr(type, member) ({ sizeof(((type *)0)->member); })
#define BOOT_PARAM_PRESERVE(struct_member) \
{ \
.start = offsetof(struct boot_params, struct_member), \
.len = sizeof_mbr(struct boot_params, struct_member), \
}
struct boot_params_to_save {
unsigned int start;
unsigned int len;
};
static void sanitize_boot_params(struct boot_params *boot_params) static void sanitize_boot_params(struct boot_params *boot_params)
{ {
/* /*
@ -35,21 +49,40 @@ static void sanitize_boot_params(struct boot_params *boot_params)
* problems again. * problems again.
*/ */
if (boot_params->sentinel) { if (boot_params->sentinel) {
/* fields in boot_params are left uninitialized, clear them */ static struct boot_params scratch;
boot_params->acpi_rsdp_addr = 0; char *bp_base = (char *)boot_params;
memset(&boot_params->ext_ramdisk_image, 0, char *save_base = (char *)&scratch;
(char *)&boot_params->efi_info - int i;
(char *)&boot_params->ext_ramdisk_image);
memset(&boot_params->kbd_status, 0, const struct boot_params_to_save to_save[] = {
(char *)&boot_params->hdr - BOOT_PARAM_PRESERVE(screen_info),
(char *)&boot_params->kbd_status); BOOT_PARAM_PRESERVE(apm_bios_info),
memset(&boot_params->_pad7[0], 0, BOOT_PARAM_PRESERVE(tboot_addr),
(char *)&boot_params->edd_mbr_sig_buffer[0] - BOOT_PARAM_PRESERVE(ist_info),
(char *)&boot_params->_pad7[0]); BOOT_PARAM_PRESERVE(acpi_rsdp_addr),
memset(&boot_params->_pad8[0], 0, BOOT_PARAM_PRESERVE(hd0_info),
(char *)&boot_params->eddbuf[0] - BOOT_PARAM_PRESERVE(hd1_info),
(char *)&boot_params->_pad8[0]); BOOT_PARAM_PRESERVE(sys_desc_table),
memset(&boot_params->_pad9[0], 0, sizeof(boot_params->_pad9)); BOOT_PARAM_PRESERVE(olpc_ofw_header),
BOOT_PARAM_PRESERVE(efi_info),
BOOT_PARAM_PRESERVE(alt_mem_k),
BOOT_PARAM_PRESERVE(scratch),
BOOT_PARAM_PRESERVE(e820_entries),
BOOT_PARAM_PRESERVE(eddbuf_entries),
BOOT_PARAM_PRESERVE(edd_mbr_sig_buf_entries),
BOOT_PARAM_PRESERVE(edd_mbr_sig_buffer),
BOOT_PARAM_PRESERVE(e820_table),
BOOT_PARAM_PRESERVE(eddbuf),
};
memset(&scratch, 0, sizeof(scratch));
for (i = 0; i < ARRAY_SIZE(to_save); i++) {
memcpy(save_base + to_save[i].start,
bp_base + to_save[i].start, to_save[i].len);
}
memcpy(boot_params, save_base, sizeof(*boot_params));
} }
} }