[PATCH 3.16.y-ckt 012/130] arm64/efi: map the entire UEFI vendor string before reading it

From: Luis Henriques
Date: Fri Sep 04 2015 - 09:56:33 EST

3.16.7-ckt17 -stable review patch. If anyone has any objections, please let me know.


From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>

commit f91b1feada0b6f0a4d33648155b3ded2c4e0707e upstream.

At boot, the UTF-16 UEFI vendor string is copied from the system
table into a char array with a size of 100 bytes. However, this
size of 100 bytes is also used for memremapping() the source,
which may not be sufficient if the vendor string exceeds 50
UTF-16 characters, and the placement of the vendor string inside
a 4 KB page happens to leave the end unmapped.

So use the correct '100 * sizeof(efi_char16_t)' for the size of
the mapping.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx>
Fixes: f84d02755f5a ("arm64: add EFI runtime services")
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
arch/arm64/kernel/efi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c
index 6b6bc795f72d..ddc7e78b51d8 100644
--- a/arch/arm64/kernel/efi.c
+++ b/arch/arm64/kernel/efi.c
@@ -98,7 +98,7 @@ static int __init uefi_init(void)

/* Show what we know for posterity */
c16 = early_memremap(efi.systab->fw_vendor,
- sizeof(vendor));
+ sizeof(vendor) * sizeof(efi_char16_t));
if (c16) {
for (i = 0; i < (int) sizeof(vendor) - 1 && *c16; ++i)
vendor[i] = c16[i];
@@ -113,7 +113,7 @@ static int __init uefi_init(void)
if (retval == 0)
set_bit(EFI_CONFIG_TABLES, &efi.flags);

- early_memunmap(c16, sizeof(vendor));
+ early_memunmap(c16, sizeof(vendor) * sizeof(efi_char16_t));
early_memunmap(efi.systab, sizeof(efi_system_table_t));

return retval;
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