| From | Greg Kroah-Hartman <> | Subject | [PATCH 5.10 155/157] firmware/efi: Fix a use after bug in efi_mem_reserve_persistent | Date | Mon, 22 Mar 2021 13:28:32 +0100 |
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From: Lv Yunlong <lyl2019@mail.ustc.edu.cn>
commit 9ceee7d0841a8f7d7644021ba7d4cc1fbc7966e3 upstream.
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: 18df7577adae6 ("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/firmware/efi/efi.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
--- a/drivers/firmware/efi/efi.c +++ b/drivers/firmware/efi/efi.c @@ -927,7 +927,7 @@ int __ref efi_mem_reserve_persistent(phy } /* 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(phy memunmap(rsv); return efi_mem_reserve_iomem(addr, size); } + prsv = rsv->next; memunmap(rsv); }
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