* [PATCH 1/2] Revert "lzo: properly check for overruns"
2014-11-03 14:47 [PATCH 0/2] lzo: refine overrun checking Jan Beulich
@ 2014-11-03 15:01 ` Jan Beulich
2014-11-03 15:02 ` [PATCH 2/2] lzo: check for length overrun in variable length encoding Jan Beulich
2014-11-04 9:37 ` [PATCH 0/2] lzo: refine overrun checking Ian Campbell
2 siblings, 0 replies; 6+ messages in thread
From: Jan Beulich @ 2014-11-03 15:01 UTC (permalink / raw)
To: xen-devel; +Cc: Ian Campbell, Keir Fraser, Ian Jackson, Tim Deegan
[-- Attachment #1: Type: text/plain, Size: 6064 bytes --]
This reverts commit 504f70b6 ("lzo: properly check for overruns").
As analysed by Willem Pinckaers, this fix is still incomplete on
certain rare corner cases, and it is easier to restart from the
original code.
Reported-by: Willem Pinckaers <willem@lekkertech.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
[original Linux commit: af958a38]
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/common/lzo.c
+++ b/xen/common/lzo.c
@@ -375,31 +375,11 @@ int lzo1x_1_compress(const unsigned char
* Richard Purdie <rpurdie@openedhand.com>
*/
-#define HAVE_IP(t, x) \
- (((size_t)(ip_end - ip) >= (size_t)(t + x)) && \
- (((t + x) >= t) && ((t + x) >= x)))
-
-#define HAVE_OP(t, x) \
- (((size_t)(op_end - op) >= (size_t)(t + x)) && \
- (((t + x) >= t) && ((t + x) >= x)))
-
-#define NEED_IP(t, x) \
- do { \
- if (!HAVE_IP(t, x)) \
- goto input_overrun; \
- } while (0)
-
-#define NEED_OP(t, x) \
- do { \
- if (!HAVE_OP(t, x)) \
- goto output_overrun; \
- } while (0)
-
-#define TEST_LB(m_pos) \
- do { \
- if ((m_pos) < out) \
- goto lookbehind_overrun; \
- } while (0)
+#define HAVE_IP(x) ((size_t)(ip_end - ip) >= (size_t)(x))
+#define HAVE_OP(x) ((size_t)(op_end - op) >= (size_t)(x))
+#define NEED_IP(x) if (!HAVE_IP(x)) goto input_overrun
+#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
+#define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun
int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len)
@@ -434,14 +414,14 @@ int lzo1x_decompress_safe(const unsigned
while (unlikely(*ip == 0)) {
t += 255;
ip++;
- NEED_IP(1, 0);
+ NEED_IP(1);
}
t += 15 + *ip++;
}
t += 3;
copy_literal_run:
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
- if (likely(HAVE_IP(t, 15) && HAVE_OP(t, 15))) {
+ if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
const unsigned char *ie = ip + t;
unsigned char *oe = op + t;
do {
@@ -457,8 +437,8 @@ int lzo1x_decompress_safe(const unsigned
} else
#endif
{
- NEED_OP(t, 0);
- NEED_IP(t, 3);
+ NEED_OP(t);
+ NEED_IP(t + 3);
do {
*op++ = *ip++;
} while (--t > 0);
@@ -471,7 +451,7 @@ int lzo1x_decompress_safe(const unsigned
m_pos -= t >> 2;
m_pos -= *ip++ << 2;
TEST_LB(m_pos);
- NEED_OP(2, 0);
+ NEED_OP(2);
op[0] = m_pos[0];
op[1] = m_pos[1];
op += 2;
@@ -495,10 +475,10 @@ int lzo1x_decompress_safe(const unsigned
while (unlikely(*ip == 0)) {
t += 255;
ip++;
- NEED_IP(1, 0);
+ NEED_IP(1);
}
t += 31 + *ip++;
- NEED_IP(2, 0);
+ NEED_IP(2);
}
m_pos = op - 1;
next = get_unaligned_le16(ip);
@@ -513,10 +493,10 @@ int lzo1x_decompress_safe(const unsigned
while (unlikely(*ip == 0)) {
t += 255;
ip++;
- NEED_IP(1, 0);
+ NEED_IP(1);
}
t += 7 + *ip++;
- NEED_IP(2, 0);
+ NEED_IP(2);
}
next = get_unaligned_le16(ip);
ip += 2;
@@ -530,7 +510,7 @@ int lzo1x_decompress_safe(const unsigned
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (op - m_pos >= 8) {
unsigned char *oe = op + t;
- if (likely(HAVE_OP(t, 15))) {
+ if (likely(HAVE_OP(t + 15))) {
do {
COPY8(op, m_pos);
op += 8;
@@ -540,7 +520,7 @@ int lzo1x_decompress_safe(const unsigned
m_pos += 8;
} while (op < oe);
op = oe;
- if (HAVE_IP(6, 0)) {
+ if (HAVE_IP(6)) {
state = next;
COPY4(op, ip);
op += next;
@@ -548,7 +528,7 @@ int lzo1x_decompress_safe(const unsigned
continue;
}
} else {
- NEED_OP(t, 0);
+ NEED_OP(t);
do {
*op++ = *m_pos++;
} while (op < oe);
@@ -557,7 +537,7 @@ int lzo1x_decompress_safe(const unsigned
#endif
{
unsigned char *oe = op + t;
- NEED_OP(t, 0);
+ NEED_OP(t);
op[0] = m_pos[0];
op[1] = m_pos[1];
op += 2;
@@ -570,15 +550,15 @@ int lzo1x_decompress_safe(const unsigned
state = next;
t = next;
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
- if (likely(HAVE_IP(6, 0) && HAVE_OP(4, 0))) {
+ if (likely(HAVE_IP(6) && HAVE_OP(4))) {
COPY4(op, ip);
op += t;
ip += t;
} else
#endif
{
- NEED_IP(t, 3);
- NEED_OP(t, 0);
+ NEED_IP(t + 3);
+ NEED_OP(t);
while (t > 0) {
*op++ = *ip++;
t--;
[-- Attachment #2: lzo-revert-504f70b6.patch --]
[-- Type: text/plain, Size: 6105 bytes --]
Revert "lzo: properly check for overruns"
This reverts commit 504f70b6 ("lzo: properly check for overruns").
As analysed by Willem Pinckaers, this fix is still incomplete on
certain rare corner cases, and it is easier to restart from the
original code.
Reported-by: Willem Pinckaers <willem@lekkertech.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
[original Linux commit: af958a38]
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/common/lzo.c
+++ b/xen/common/lzo.c
@@ -375,31 +375,11 @@ int lzo1x_1_compress(const unsigned char
* Richard Purdie <rpurdie@openedhand.com>
*/
-#define HAVE_IP(t, x) \
- (((size_t)(ip_end - ip) >= (size_t)(t + x)) && \
- (((t + x) >= t) && ((t + x) >= x)))
-
-#define HAVE_OP(t, x) \
- (((size_t)(op_end - op) >= (size_t)(t + x)) && \
- (((t + x) >= t) && ((t + x) >= x)))
-
-#define NEED_IP(t, x) \
- do { \
- if (!HAVE_IP(t, x)) \
- goto input_overrun; \
- } while (0)
-
-#define NEED_OP(t, x) \
- do { \
- if (!HAVE_OP(t, x)) \
- goto output_overrun; \
- } while (0)
-
-#define TEST_LB(m_pos) \
- do { \
- if ((m_pos) < out) \
- goto lookbehind_overrun; \
- } while (0)
+#define HAVE_IP(x) ((size_t)(ip_end - ip) >= (size_t)(x))
+#define HAVE_OP(x) ((size_t)(op_end - op) >= (size_t)(x))
+#define NEED_IP(x) if (!HAVE_IP(x)) goto input_overrun
+#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
+#define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun
int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len)
@@ -434,14 +414,14 @@ int lzo1x_decompress_safe(const unsigned
while (unlikely(*ip == 0)) {
t += 255;
ip++;
- NEED_IP(1, 0);
+ NEED_IP(1);
}
t += 15 + *ip++;
}
t += 3;
copy_literal_run:
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
- if (likely(HAVE_IP(t, 15) && HAVE_OP(t, 15))) {
+ if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
const unsigned char *ie = ip + t;
unsigned char *oe = op + t;
do {
@@ -457,8 +437,8 @@ int lzo1x_decompress_safe(const unsigned
} else
#endif
{
- NEED_OP(t, 0);
- NEED_IP(t, 3);
+ NEED_OP(t);
+ NEED_IP(t + 3);
do {
*op++ = *ip++;
} while (--t > 0);
@@ -471,7 +451,7 @@ int lzo1x_decompress_safe(const unsigned
m_pos -= t >> 2;
m_pos -= *ip++ << 2;
TEST_LB(m_pos);
- NEED_OP(2, 0);
+ NEED_OP(2);
op[0] = m_pos[0];
op[1] = m_pos[1];
op += 2;
@@ -495,10 +475,10 @@ int lzo1x_decompress_safe(const unsigned
while (unlikely(*ip == 0)) {
t += 255;
ip++;
- NEED_IP(1, 0);
+ NEED_IP(1);
}
t += 31 + *ip++;
- NEED_IP(2, 0);
+ NEED_IP(2);
}
m_pos = op - 1;
next = get_unaligned_le16(ip);
@@ -513,10 +493,10 @@ int lzo1x_decompress_safe(const unsigned
while (unlikely(*ip == 0)) {
t += 255;
ip++;
- NEED_IP(1, 0);
+ NEED_IP(1);
}
t += 7 + *ip++;
- NEED_IP(2, 0);
+ NEED_IP(2);
}
next = get_unaligned_le16(ip);
ip += 2;
@@ -530,7 +510,7 @@ int lzo1x_decompress_safe(const unsigned
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
if (op - m_pos >= 8) {
unsigned char *oe = op + t;
- if (likely(HAVE_OP(t, 15))) {
+ if (likely(HAVE_OP(t + 15))) {
do {
COPY8(op, m_pos);
op += 8;
@@ -540,7 +520,7 @@ int lzo1x_decompress_safe(const unsigned
m_pos += 8;
} while (op < oe);
op = oe;
- if (HAVE_IP(6, 0)) {
+ if (HAVE_IP(6)) {
state = next;
COPY4(op, ip);
op += next;
@@ -548,7 +528,7 @@ int lzo1x_decompress_safe(const unsigned
continue;
}
} else {
- NEED_OP(t, 0);
+ NEED_OP(t);
do {
*op++ = *m_pos++;
} while (op < oe);
@@ -557,7 +537,7 @@ int lzo1x_decompress_safe(const unsigned
#endif
{
unsigned char *oe = op + t;
- NEED_OP(t, 0);
+ NEED_OP(t);
op[0] = m_pos[0];
op[1] = m_pos[1];
op += 2;
@@ -570,15 +550,15 @@ int lzo1x_decompress_safe(const unsigned
state = next;
t = next;
#if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
- if (likely(HAVE_IP(6, 0) && HAVE_OP(4, 0))) {
+ if (likely(HAVE_IP(6) && HAVE_OP(4))) {
COPY4(op, ip);
op += t;
ip += t;
} else
#endif
{
- NEED_IP(t, 3);
- NEED_OP(t, 0);
+ NEED_IP(t + 3);
+ NEED_OP(t);
while (t > 0) {
*op++ = *ip++;
t--;
[-- Attachment #3: Type: text/plain, Size: 126 bytes --]
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^ permalink raw reply [flat|nested] 6+ messages in thread* [PATCH 2/2] lzo: check for length overrun in variable length encoding
2014-11-03 14:47 [PATCH 0/2] lzo: refine overrun checking Jan Beulich
2014-11-03 15:01 ` [PATCH 1/2] Revert "lzo: properly check for overruns" Jan Beulich
@ 2014-11-03 15:02 ` Jan Beulich
2014-11-04 11:24 ` Ian Jackson
2014-11-04 9:37 ` [PATCH 0/2] lzo: refine overrun checking Ian Campbell
2 siblings, 1 reply; 6+ messages in thread
From: Jan Beulich @ 2014-11-03 15:02 UTC (permalink / raw)
To: xen-devel; +Cc: Ian Campbell, Keir Fraser, Ian Jackson, Tim Deegan
[-- Attachment #1: Type: text/plain, Size: 4664 bytes --]
This fix ensures that we never meet an integer overflow while adding
255 while parsing a variable length encoding. It works differently from
commit 504f70b6 ("lzo: properly check for overruns") because instead of
ensuring that we don't overrun the input, which is tricky to guarantee
due to many assumptions in the code, it simply checks that the cumulated
number of 255 read cannot overflow by bounding this number.
The MAX_255_COUNT is the maximum number of times we can add 255 to a base
count without overflowing an integer. The multiply will overflow when
multiplying 255 by more than MAXINT/255. The sum will overflow earlier
depending on the base count. Since the base count is taken from a u8
and a few bits, it is safe to assume that it will always be lower than
or equal to 2*255, thus we can always prevent any overflow by accepting
two less 255 steps.
This patch also reduces the CPU overhead and actually increases performance
by 1.1% compared to the initial code, while the previous fix costs 3.1%
(measured on x86_64).
The fix needs to be backported to all currently supported stable kernels.
Reported-by: Willem Pinckaers <willem@lekkertech.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
[original Linux commit: 72cf9012]
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/common/lzo.c
+++ b/xen/common/lzo.c
@@ -381,6 +381,16 @@ int lzo1x_1_compress(const unsigned char
#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
#define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun
+/* This MAX_255_COUNT is the maximum number of times we can add 255 to a base
+ * count without overflowing an integer. The multiply will overflow when
+ * multiplying 255 by more than MAXINT/255. The sum will overflow earlier
+ * depending on the base count. Since the base count is taken from a u8
+ * and a few bits, it is safe to assume that it will always be lower than
+ * or equal to 2*255, thus we can always prevent any overflow by accepting
+ * two less 255 steps. See Documentation/lzo.txt for more information.
+ */
+#define MAX_255_COUNT ((((size_t)~0) / 255) - 2)
+
int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len)
{
@@ -411,12 +421,19 @@ int lzo1x_decompress_safe(const unsigned
if (t < 16) {
if (likely(state == 0)) {
if (unlikely(t == 0)) {
+ size_t offset;
+ const unsigned char *ip_last = ip;
+
while (unlikely(*ip == 0)) {
- t += 255;
ip++;
NEED_IP(1);
}
- t += 15 + *ip++;
+ offset = ip - ip_last;
+ if (unlikely(offset > MAX_255_COUNT))
+ return LZO_E_ERROR;
+
+ offset = (offset << 8) - offset;
+ t += offset + 15 + *ip++;
}
t += 3;
copy_literal_run:
@@ -472,12 +489,19 @@ int lzo1x_decompress_safe(const unsigned
} else if (t >= 32) {
t = (t & 31) + (3 - 1);
if (unlikely(t == 2)) {
+ size_t offset;
+ const unsigned char *ip_last = ip;
+
while (unlikely(*ip == 0)) {
- t += 255;
ip++;
NEED_IP(1);
}
- t += 31 + *ip++;
+ offset = ip - ip_last;
+ if (unlikely(offset > MAX_255_COUNT))
+ return LZO_E_ERROR;
+
+ offset = (offset << 8) - offset;
+ t += offset + 31 + *ip++;
NEED_IP(2);
}
m_pos = op - 1;
@@ -490,12 +514,19 @@ int lzo1x_decompress_safe(const unsigned
m_pos -= (t & 8) << 11;
t = (t & 7) + (3 - 1);
if (unlikely(t == 2)) {
+ size_t offset;
+ const unsigned char *ip_last = ip;
+
while (unlikely(*ip == 0)) {
- t += 255;
ip++;
NEED_IP(1);
}
- t += 7 + *ip++;
+ offset = ip - ip_last;
+ if (unlikely(offset > MAX_255_COUNT))
+ return LZO_E_ERROR;
+
+ offset = (offset << 8) - offset;
+ t += offset + 7 + *ip++;
NEED_IP(2);
}
next = get_unaligned_le16(ip);
[-- Attachment #2: lzo-check-length-overrun.patch --]
[-- Type: text/plain, Size: 4721 bytes --]
lzo: check for length overrun in variable length encoding
This fix ensures that we never meet an integer overflow while adding
255 while parsing a variable length encoding. It works differently from
commit 504f70b6 ("lzo: properly check for overruns") because instead of
ensuring that we don't overrun the input, which is tricky to guarantee
due to many assumptions in the code, it simply checks that the cumulated
number of 255 read cannot overflow by bounding this number.
The MAX_255_COUNT is the maximum number of times we can add 255 to a base
count without overflowing an integer. The multiply will overflow when
multiplying 255 by more than MAXINT/255. The sum will overflow earlier
depending on the base count. Since the base count is taken from a u8
and a few bits, it is safe to assume that it will always be lower than
or equal to 2*255, thus we can always prevent any overflow by accepting
two less 255 steps.
This patch also reduces the CPU overhead and actually increases performance
by 1.1% compared to the initial code, while the previous fix costs 3.1%
(measured on x86_64).
The fix needs to be backported to all currently supported stable kernels.
Reported-by: Willem Pinckaers <willem@lekkertech.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
[original Linux commit: 72cf9012]
Signed-off-by: Jan Beulich <jbeulich@suse.com>
--- a/xen/common/lzo.c
+++ b/xen/common/lzo.c
@@ -381,6 +381,16 @@ int lzo1x_1_compress(const unsigned char
#define NEED_OP(x) if (!HAVE_OP(x)) goto output_overrun
#define TEST_LB(m_pos) if ((m_pos) < out) goto lookbehind_overrun
+/* This MAX_255_COUNT is the maximum number of times we can add 255 to a base
+ * count without overflowing an integer. The multiply will overflow when
+ * multiplying 255 by more than MAXINT/255. The sum will overflow earlier
+ * depending on the base count. Since the base count is taken from a u8
+ * and a few bits, it is safe to assume that it will always be lower than
+ * or equal to 2*255, thus we can always prevent any overflow by accepting
+ * two less 255 steps. See Documentation/lzo.txt for more information.
+ */
+#define MAX_255_COUNT ((((size_t)~0) / 255) - 2)
+
int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
unsigned char *out, size_t *out_len)
{
@@ -411,12 +421,19 @@ int lzo1x_decompress_safe(const unsigned
if (t < 16) {
if (likely(state == 0)) {
if (unlikely(t == 0)) {
+ size_t offset;
+ const unsigned char *ip_last = ip;
+
while (unlikely(*ip == 0)) {
- t += 255;
ip++;
NEED_IP(1);
}
- t += 15 + *ip++;
+ offset = ip - ip_last;
+ if (unlikely(offset > MAX_255_COUNT))
+ return LZO_E_ERROR;
+
+ offset = (offset << 8) - offset;
+ t += offset + 15 + *ip++;
}
t += 3;
copy_literal_run:
@@ -472,12 +489,19 @@ int lzo1x_decompress_safe(const unsigned
} else if (t >= 32) {
t = (t & 31) + (3 - 1);
if (unlikely(t == 2)) {
+ size_t offset;
+ const unsigned char *ip_last = ip;
+
while (unlikely(*ip == 0)) {
- t += 255;
ip++;
NEED_IP(1);
}
- t += 31 + *ip++;
+ offset = ip - ip_last;
+ if (unlikely(offset > MAX_255_COUNT))
+ return LZO_E_ERROR;
+
+ offset = (offset << 8) - offset;
+ t += offset + 31 + *ip++;
NEED_IP(2);
}
m_pos = op - 1;
@@ -490,12 +514,19 @@ int lzo1x_decompress_safe(const unsigned
m_pos -= (t & 8) << 11;
t = (t & 7) + (3 - 1);
if (unlikely(t == 2)) {
+ size_t offset;
+ const unsigned char *ip_last = ip;
+
while (unlikely(*ip == 0)) {
- t += 255;
ip++;
NEED_IP(1);
}
- t += 7 + *ip++;
+ offset = ip - ip_last;
+ if (unlikely(offset > MAX_255_COUNT))
+ return LZO_E_ERROR;
+
+ offset = (offset << 8) - offset;
+ t += offset + 7 + *ip++;
NEED_IP(2);
}
next = get_unaligned_le16(ip);
[-- Attachment #3: Type: text/plain, Size: 126 bytes --]
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^ permalink raw reply [flat|nested] 6+ messages in thread