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EFI: fix potential memory overwrite due to mmap table 

Some bios may have more mmap table entry than our current limitation
which is 128. This will lead to a memory overwrite, so add a check to
prevent this and enlarge the limitation to 256. This should fix most
bioses.

Tracked-On: #2435
Signed-off-by: Tw <wei.tan@intel.com>
Acked-by: Anthony Xu <anthony.xu@intel.com>
This commit is contained in:
Tw 2019-01-28 09:42:40 +08:00 committed by wenlingz
parent b038ade21c
commit 69371f419b
2 changed files with 16 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
efi-stub/boot.c
View File

@ -75,7 +75,7 @@ EFI_STATUS construct_mbi(EFI_PHYSICAL_ADDRESS hv_hpa, struct multiboot_info *mbi
UINTN desc_size;
EFI_MEMORY_DESCRIPTOR *map_buf;
EFI_STATUS err = EFI_SUCCESS;
int32_t i, j;
int32_t i, j, mmap_entry_count;
/* We're just interested in the map's size for now */
map_size = 0;
@ -111,10 +111,11 @@ again:
goto out;
}
mmap_entry_count = map_size / desc_size;
/*
* Convert the EFI memory map to E820.
*/
for (i = 0, j = 0; i < map_size / desc_size; i++) {
for (i = 0, j = 0; i < mmap_entry_count && j < MBOOT_MMAP_NUMS - 1; i++) {
EFI_MEMORY_DESCRIPTOR *d;
uint32_t e820_type = 0;
@ -165,6 +166,18 @@ again:
}
}
/*
* if we haven't gone through all the mmap table entries,
* there must be a memory overwrite if we continue,
* so just abort anyway.
*/
if (i < mmap_entry_count) {
Print(L": bios provides %d mmap entries which is beyond limitation[%d]\n",
mmap_entry_count, MBOOT_MMAP_NUMS-1);
err = EFI_INVALID_PARAMETER;
goto out;
}
/* switch hv memory region(0x20000000 ~ 0x22000000) to
* available RAM in e820 table
*/

2
efi-stub/boot.h
View File

@ -73,7 +73,7 @@ typedef void(*hv_func)(int32_t, struct multiboot_info*);
* We allocate memory for the following struct together with hyperivosr itself
* memory allocation during boot.
*/
#define MBOOT_MMAP_NUMS 128
#define MBOOT_MMAP_NUMS 256
#define MBOOT_MMAP_SIZE (sizeof(struct multiboot_mmap) * MBOOT_MMAP_NUMS)
#define MBOOT_INFO_SIZE (sizeof(struct multiboot_info))
#define BOOT_CTX_SIZE (sizeof(struct efi_context))