[lttng-dev] [PATCH lttng-tools 1/2] Fix: Connect timeout arithmetic in inet/inet6 (v4)
Mathieu Desnoyers
mathieu.desnoyers at efficios.com
Tue Nov 13 12:12:20 EST 2018
The nanoseconds part of the timespec struct time_a is not always
bigger than time_b since it wrap around each seconds.
Use 64-bit arithmetic to perform the difference.
Merge/move duplicated code into utils.c.
This function is really doing two things. Split it into timespec_to_ms()
and timespec_abs_diff().
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
Changes since v1:
- Use NSEC_PER_SEC constant.
Changes since v2:
- Move prototypes to time.h.
- Adapt timespec_to_ms() range check to take into account tv_nsec beyond
1000000000-1.
Changes since v3:
- Use remainer for detection of overflow.
- set errno to EOVERFLOW in timespec_to_ms.
---
src/common/common.h | 1 +
src/common/sessiond-comm/inet.c | 27 +++++++--------------------
src/common/sessiond-comm/inet6.c | 27 +++++++--------------------
src/common/time.h | 15 +++++++++++++++
src/common/utils.c | 36 ++++++++++++++++++++++++++++++++++++
5 files changed, 66 insertions(+), 40 deletions(-)
diff --git a/src/common/common.h b/src/common/common.h
index 41eb0361..9168a245 100644
--- a/src/common/common.h
+++ b/src/common/common.h
@@ -23,5 +23,6 @@
#include "macros.h"
#include "runas.h"
#include "readwrite.h"
+#include "time.h"
#endif /* _COMMON_H */
diff --git a/src/common/sessiond-comm/inet.c b/src/common/sessiond-comm/inet.c
index e0b3e7a9..ac450dbc 100644
--- a/src/common/sessiond-comm/inet.c
+++ b/src/common/sessiond-comm/inet.c
@@ -112,31 +112,13 @@ int connect_no_timeout(struct lttcomm_sock *sock)
sizeof(sock->sockaddr.addr.sin));
}
-/*
- * Return time_a - time_b in milliseconds.
- */
-static
-unsigned long time_diff_ms(struct timespec *time_a,
- struct timespec *time_b)
-{
- time_t sec_diff;
- long nsec_diff;
- unsigned long result_ms;
-
- sec_diff = time_a->tv_sec - time_b->tv_sec;
- nsec_diff = time_a->tv_nsec - time_b->tv_nsec;
-
- result_ms = sec_diff * MSEC_PER_SEC;
- result_ms += nsec_diff / NSEC_PER_MSEC;
- return result_ms;
-}
-
static
int connect_with_timeout(struct lttcomm_sock *sock)
{
unsigned long timeout = lttcomm_get_network_timeout();
int ret, flags, connect_ret;
struct timespec orig_time, cur_time;
+ unsigned long diff_ms;
ret = fcntl(sock->fd, F_GETFL, 0);
if (ret == -1) {
@@ -217,7 +199,12 @@ int connect_with_timeout(struct lttcomm_sock *sock)
connect_ret = ret;
goto error;
}
- } while (time_diff_ms(&cur_time, &orig_time) < timeout);
+ if (timespec_to_ms(timespec_abs_diff(cur_time, orig_time), &diff_ms) < 0) {
+ ERR("timespec_to_ms input overflows milliseconds output");
+ connect_ret = -1;
+ goto error;
+ }
+ } while (diff_ms < timeout);
/* Timeout */
errno = ETIMEDOUT;
diff --git a/src/common/sessiond-comm/inet6.c b/src/common/sessiond-comm/inet6.c
index dfb5fc5d..03b6627d 100644
--- a/src/common/sessiond-comm/inet6.c
+++ b/src/common/sessiond-comm/inet6.c
@@ -110,31 +110,13 @@ int connect_no_timeout(struct lttcomm_sock *sock)
sizeof(sock->sockaddr.addr.sin6));
}
-/*
- * Return time_a - time_b in milliseconds.
- */
-static
-unsigned long time_diff_ms(struct timespec *time_a,
- struct timespec *time_b)
-{
- time_t sec_diff;
- long nsec_diff;
- unsigned long result_ms;
-
- sec_diff = time_a->tv_sec - time_b->tv_sec;
- nsec_diff = time_a->tv_nsec - time_b->tv_nsec;
-
- result_ms = sec_diff * MSEC_PER_SEC;
- result_ms += nsec_diff / NSEC_PER_MSEC;
- return result_ms;
-}
-
static
int connect_with_timeout(struct lttcomm_sock *sock)
{
unsigned long timeout = lttcomm_get_network_timeout();
int ret, flags, connect_ret;
struct timespec orig_time, cur_time;
+ unsigned long diff_ms;
ret = fcntl(sock->fd, F_GETFL, 0);
if (ret == -1) {
@@ -216,7 +198,12 @@ int connect_with_timeout(struct lttcomm_sock *sock)
connect_ret = ret;
goto error;
}
- } while (time_diff_ms(&cur_time, &orig_time) < timeout);
+ if (timespec_to_ms(timespec_abs_diff(cur_time, orig_time), &diff_ms) < 0) {
+ ERR("timespec_to_ms input overflows milliseconds output");
+ connect_ret = -1;
+ goto error;
+ }
+ } while (diff_ms < timeout);
/* Timeout */
errno = ETIMEDOUT;
diff --git a/src/common/time.h b/src/common/time.h
index 81770779..8a7dd958 100644
--- a/src/common/time.h
+++ b/src/common/time.h
@@ -19,9 +19,24 @@
#ifndef LTTNG_TIME_H
#define LTTNG_TIME_H
+#include <time.h>
+
#define MSEC_PER_SEC 1000ULL
#define NSEC_PER_SEC 1000000000ULL
#define NSEC_PER_MSEC 1000000ULL
#define NSEC_PER_USEC 1000ULL
+/*
+ * timespec_to_ms: Convert timespec to milliseconds.
+ *
+ * Returns 0 on success, else -1 on error. errno is set to EOVERFLOW if
+ * input would overflow the output in milliseconds.
+ */
+int timespec_to_ms(struct timespec ts, unsigned long *ms);
+
+/*
+ * timespec_abs_diff: Absolute difference between timespec.
+ */
+struct timespec timespec_abs_diff(struct timespec ts_a, struct timespec ts_b);
+
#endif /* LTTNG_TIME_H */
diff --git a/src/common/utils.c b/src/common/utils.c
index 3442bef8..08139e5e 100644
--- a/src/common/utils.c
+++ b/src/common/utils.c
@@ -41,6 +41,7 @@
#include "utils.h"
#include "defaults.h"
+#include "time.h"
/*
* Return a partial realpath(3) of the path even if the full path does not
@@ -1645,3 +1646,38 @@ int utils_show_help(int section, const char *page_name,
end:
return ret;
}
+
+LTTNG_HIDDEN
+int timespec_to_ms(struct timespec ts, unsigned long *ms)
+{
+ unsigned long res, remain_ms;
+
+ if (ts.tv_sec > ULONG_MAX / MSEC_PER_SEC) {
+ errno = EOVERFLOW;
+ return -1; /* multiplication overflow */
+ }
+ res = ts.tv_sec * MSEC_PER_SEC;
+ remain_ms = ULONG_MAX - res;
+ if (ts.tv_nsec / NSEC_PER_MSEC > remain_ms) {
+ errno = EOVERFLOW;
+ return -1; /* addition overflow */
+ }
+ res += ts.tv_nsec / NSEC_PER_MSEC;
+ *ms = res;
+ return 0;
+}
+
+LTTNG_HIDDEN
+struct timespec timespec_abs_diff(struct timespec t1, struct timespec t2)
+{
+ uint64_t ts1 = (uint64_t) t1.tv_sec * (uint64_t) NSEC_PER_SEC +
+ (uint64_t) t1.tv_nsec;
+ uint64_t ts2 = (uint64_t) t2.tv_sec * (uint64_t) NSEC_PER_SEC +
+ (uint64_t) t2.tv_nsec;
+ uint64_t diff = max(ts1, ts2) - min(ts1, ts2);
+ struct timespec res;
+
+ res.tv_sec = diff / (uint64_t) NSEC_PER_SEC;
+ res.tv_nsec = diff % (uint64_t) NSEC_PER_SEC;
+ return res;
+}
--
2.11.0
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