Commit b20209c9 authored by Junaid Shahid's avatar Junaid Shahid Committed by Herbert Xu

crypto: aesni - Fix out-of-bounds access of the data buffer in generic-gcm-aesni

The aesni_gcm_enc/dec functions can access memory before the start of
the data buffer if the length of the data buffer is less than 16 bytes.
This is because they perform the read via a single 16-byte load. This
can potentially result in accessing a page that is not mapped and thus
causing the machine to crash. This patch fixes that by reading the
partial block byte-by-byte and optionally an via 8-byte load if the block
was at least 8 bytes.

Fixes: 0487ccac ("crypto: aesni - make non-AVX AES-GCM work with any aadlen")
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarJunaid Shahid <junaids@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 02d9e320
......@@ -256,6 +256,37 @@ aad_shift_arr:
pxor \TMP1, \GH # result is in TMP1
.endm
# Reads DLEN bytes starting at DPTR and stores in XMMDst
# where 0 < DLEN < 16
# Clobbers %rax, DLEN and XMM1
.macro READ_PARTIAL_BLOCK DPTR DLEN XMM1 XMMDst
cmp $8, \DLEN
jl _read_lt8_\@
mov (\DPTR), %rax
MOVQ_R64_XMM %rax, \XMMDst
sub $8, \DLEN
jz _done_read_partial_block_\@
xor %eax, %eax
_read_next_byte_\@:
shl $8, %rax
mov 7(\DPTR, \DLEN, 1), %al
dec \DLEN
jnz _read_next_byte_\@
MOVQ_R64_XMM %rax, \XMM1
pslldq $8, \XMM1
por \XMM1, \XMMDst
jmp _done_read_partial_block_\@
_read_lt8_\@:
xor %eax, %eax
_read_next_byte_lt8_\@:
shl $8, %rax
mov -1(\DPTR, \DLEN, 1), %al
dec \DLEN
jnz _read_next_byte_lt8_\@
MOVQ_R64_XMM %rax, \XMMDst
_done_read_partial_block_\@:
.endm
/*
* if a = number of total plaintext bytes
* b = floor(a/16)
......@@ -1385,14 +1416,6 @@ _esb_loop_\@:
*
* AAD Format with 64-bit Extended Sequence Number
*
* aadLen:
* from the definition of the spec, aadLen can only be 8 or 12 bytes.
* The code supports 16 too but for other sizes, the code will fail.
*
* TLen:
* from the definition of the spec, TLen can only be 8, 12 or 16 bytes.
* For other sizes, the code will fail.
*
* poly = x^128 + x^127 + x^126 + x^121 + 1
*
*****************************************************************************/
......@@ -1486,19 +1509,16 @@ _zero_cipher_left_decrypt:
PSHUFB_XMM %xmm10, %xmm0
ENCRYPT_SINGLE_BLOCK %xmm0, %xmm1 # E(K, Yn)
sub $16, %r11
add %r13, %r11
movdqu (%arg3,%r11,1), %xmm1 # receive the last <16 byte block
lea SHIFT_MASK+16(%rip), %r12
sub %r13, %r12
# adjust the shuffle mask pointer to be able to shift 16-%r13 bytes
# (%r13 is the number of bytes in plaintext mod 16)
movdqu (%r12), %xmm2 # get the appropriate shuffle mask
PSHUFB_XMM %xmm2, %xmm1 # right shift 16-%r13 butes
lea (%arg3,%r11,1), %r10
mov %r13, %r12
READ_PARTIAL_BLOCK %r10 %r12 %xmm2 %xmm1
lea ALL_F+16(%rip), %r12
sub %r13, %r12
movdqa %xmm1, %xmm2
pxor %xmm1, %xmm0 # Ciphertext XOR E(K, Yn)
movdqu ALL_F-SHIFT_MASK(%r12), %xmm1
movdqu (%r12), %xmm1
# get the appropriate mask to mask out top 16-%r13 bytes of %xmm0
pand %xmm1, %xmm0 # mask out top 16-%r13 bytes of %xmm0
pand %xmm1, %xmm2
......@@ -1507,9 +1527,6 @@ _zero_cipher_left_decrypt:
pxor %xmm2, %xmm8
GHASH_MUL %xmm8, %xmm13, %xmm9, %xmm10, %xmm11, %xmm5, %xmm6
# GHASH computation for the last <16 byte block
sub %r13, %r11
add $16, %r11
# output %r13 bytes
MOVQ_R64_XMM %xmm0, %rax
......@@ -1663,14 +1680,6 @@ ENDPROC(aesni_gcm_dec)
*
* AAD Format with 64-bit Extended Sequence Number
*
* aadLen:
* from the definition of the spec, aadLen can only be 8 or 12 bytes.
* The code supports 16 too but for other sizes, the code will fail.
*
* TLen:
* from the definition of the spec, TLen can only be 8, 12 or 16 bytes.
* For other sizes, the code will fail.
*
* poly = x^128 + x^127 + x^126 + x^121 + 1
***************************************************************************/
ENTRY(aesni_gcm_enc)
......@@ -1763,19 +1772,16 @@ _zero_cipher_left_encrypt:
movdqa SHUF_MASK(%rip), %xmm10
PSHUFB_XMM %xmm10, %xmm0
ENCRYPT_SINGLE_BLOCK %xmm0, %xmm1 # Encrypt(K, Yn)
sub $16, %r11
add %r13, %r11
movdqu (%arg3,%r11,1), %xmm1 # receive the last <16 byte blocks
lea SHIFT_MASK+16(%rip), %r12
lea (%arg3,%r11,1), %r10
mov %r13, %r12
READ_PARTIAL_BLOCK %r10 %r12 %xmm2 %xmm1
lea ALL_F+16(%rip), %r12
sub %r13, %r12
# adjust the shuffle mask pointer to be able to shift 16-r13 bytes
# (%r13 is the number of bytes in plaintext mod 16)
movdqu (%r12), %xmm2 # get the appropriate shuffle mask
PSHUFB_XMM %xmm2, %xmm1 # shift right 16-r13 byte
pxor %xmm1, %xmm0 # Plaintext XOR Encrypt(K, Yn)
movdqu ALL_F-SHIFT_MASK(%r12), %xmm1
movdqu (%r12), %xmm1
# get the appropriate mask to mask out top 16-r13 bytes of xmm0
pand %xmm1, %xmm0 # mask out top 16-r13 bytes of xmm0
movdqa SHUF_MASK(%rip), %xmm10
......@@ -1784,9 +1790,6 @@ _zero_cipher_left_encrypt:
pxor %xmm0, %xmm8
GHASH_MUL %xmm8, %xmm13, %xmm9, %xmm10, %xmm11, %xmm5, %xmm6
# GHASH computation for the last <16 byte block
sub %r13, %r11
add $16, %r11
movdqa SHUF_MASK(%rip), %xmm10
PSHUFB_XMM %xmm10, %xmm0
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment