net: ipv4: tcp_probe: cleanup snprintf() use
snprintf() returns number of bytes that were copied if there is no overflow.
This code uses return value as number of copied bytes. Theoretically format
string '%lu.%09lu %pI4:%u %pI4:%u %d %#x %#x %u %u %u %u\n' may be expanded
up to 163 bytes. In reality tv.tv_sec is just few bytes instead of 20, 2 ports
are just 5 bytes each instead of 10, length is 5 bytes instead of 10. The rest
is an unstrusted input. Theoretically if tv_sec is big then copy_to_user() would
overflow tbuf.
tbuf was increased to fit in 163 bytes. snprintf() is used to follow return
value semantic.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_probe.c b/net/ipv4/tcp_probe.c
index 6211e21..85ee7eb 100644
--- a/net/ipv4/tcp_probe.c
+++ b/net/ipv4/tcp_probe.c
@@ -154,7 +154,7 @@
struct timespec tv
= ktime_to_timespec(ktime_sub(p->tstamp, tcp_probe.start));
- return snprintf(tbuf, n,
+ return scnprintf(tbuf, n,
"%lu.%09lu %pI4:%u %pI4:%u %d %#x %#x %u %u %u %u\n",
(unsigned long) tv.tv_sec,
(unsigned long) tv.tv_nsec,
@@ -174,7 +174,7 @@
return -EINVAL;
while (cnt < len) {
- char tbuf[128];
+ char tbuf[164];
int width;
/* Wait for data in buffer */