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firmware/efi: Fix a use after bug in efi_mem_reserve_persistent

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In the for loop in efi_mem_reserve_persistent(), prsv = rsv->next
use the unmapped rsv. Use the unmapped pages will cause segment
fault.

Fixes: 18df7577ad ("efi/memreserve: deal with memreserve entries in unmapped memory")
Signed-off-by: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
This commit is contained in:
Lv Yunlong 2021-03-10 00:31:27 -08:00 committed by Ard Biesheuvel
parent 483028edac
commit 9ceee7d084
1 changed files with 2 additions and 1 deletions
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3
drivers/firmware/efi/efi.c
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@ -927,7 +927,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
}
/* first try to find a slot in an existing linked list entry */
for (prsv = efi_memreserve_root->next; prsv; prsv = rsv->next) {
for (prsv = efi_memreserve_root->next; prsv; ) {
rsv = memremap(prsv, sizeof(*rsv), MEMREMAP_WB);
index = atomic_fetch_add_unless(&rsv->count, 1, rsv->size);
if (index < rsv->size) {
@ -937,6 +937,7 @@ int __ref efi_mem_reserve_persistent(phys_addr_t addr, u64 size)
memunmap(rsv);
return efi_mem_reserve_iomem(addr, size);
}
prsv = rsv->next;
memunmap(rsv);
}