From cf9fcdc71a3b9e5380a9becf1ae01a56eeb69faa Mon Sep 17 00:00:00 2001
From: Aaron Lehmann <aaron.lehmann@docker.com>
Date: Fri, 15 Jan 2016 16:04:52 -0800
Subject: [PATCH] Avoid panic when spec file is missing sections under
 Resources

Check pointers against nil before dereferencing them. Skip any sections
that are nil, since that's equivalent to having no values defined for
those sections.

Signed-off-by: Aaron Lehmann <aaron.lehmann@docker.com>
---
 linux/linux.go | 98 +++++++++++++++++++++++++++-----------------------
 1 file changed, 53 insertions(+), 45 deletions(-)

diff --git a/linux/linux.go b/linux/linux.go
index 7ce667e..befea25 100644
--- a/linux/linux.go
+++ b/linux/linux.go
@@ -626,47 +626,53 @@ func (rt *libcontainerRuntime) createCgroupConfig(name string, spec *specs.Linux
 	}
 	cr.Resources = c
 	r := spec.Linux.Resources
-	if r.Memory.Limit != nil {
-		c.Memory = int64(*r.Memory.Limit)
+	if r.Memory != nil {
+		if r.Memory.Limit != nil {
+			c.Memory = int64(*r.Memory.Limit)
+		}
+		if r.Memory.Reservation != nil {
+			c.MemoryReservation = int64(*r.Memory.Reservation)
+		}
+		if r.Memory.Swap != nil {
+			c.MemorySwap = int64(*r.Memory.Swap)
+		}
+		if r.Memory.Kernel != nil {
+			c.KernelMemory = int64(*r.Memory.Kernel)
+		}
+		if r.Memory.Swappiness != nil {
+			c.MemorySwappiness = int64(*r.Memory.Swappiness)
+		}
 	}
-	if r.Memory.Reservation != nil {
-		c.MemoryReservation = int64(*r.Memory.Reservation)
+	if r.CPU != nil {
+		if r.CPU.Shares != nil {
+			c.CpuShares = int64(*r.CPU.Shares)
+		}
+		if r.CPU.Quota != nil {
+			c.CpuQuota = int64(*r.CPU.Quota)
+		}
+		if r.CPU.Period != nil {
+			c.CpuPeriod = int64(*r.CPU.Period)
+		}
+		if r.CPU.RealtimeRuntime != nil {
+			c.CpuRtRuntime = int64(*r.CPU.RealtimeRuntime)
+		}
+		if r.CPU.RealtimePeriod != nil {
+			c.CpuRtPeriod = int64(*r.CPU.RealtimePeriod)
+		}
+		if r.CPU.Cpus != nil {
+			c.CpusetCpus = *r.CPU.Cpus
+		}
+		if r.CPU.Mems != nil {
+			c.CpusetMems = *r.CPU.Mems
+		}
 	}
-	if r.Memory.Swap != nil {
-		c.MemorySwap = int64(*r.Memory.Swap)
-	}
-	if r.Memory.Kernel != nil {
-		c.KernelMemory = int64(*r.Memory.Kernel)
-	}
-	if r.Memory.Swappiness != nil {
-		c.MemorySwappiness = int64(*r.Memory.Swappiness)
-	}
-	if r.CPU.Shares != nil {
-		c.CpuShares = int64(*r.CPU.Shares)
-	}
-	if r.CPU.Quota != nil {
-		c.CpuQuota = int64(*r.CPU.Quota)
-	}
-	if r.CPU.Period != nil {
-		c.CpuPeriod = int64(*r.CPU.Period)
-	}
-	if r.CPU.RealtimeRuntime != nil {
-		c.CpuRtRuntime = int64(*r.CPU.RealtimeRuntime)
-	}
-	if r.CPU.RealtimePeriod != nil {
-		c.CpuRtPeriod = int64(*r.CPU.RealtimePeriod)
-	}
-	if r.CPU.Cpus != nil {
-		c.CpusetCpus = *r.CPU.Cpus
-	}
-	if r.CPU.Mems != nil {
-		c.CpusetMems = *r.CPU.Mems
-	}
-	if r.BlockIO.Weight != nil {
-		c.BlkioWeight = *r.BlockIO.Weight
-	}
-	if r.BlockIO.LeafWeight != nil {
-		c.BlkioLeafWeight = *r.BlockIO.LeafWeight
+	if r.BlockIO != nil {
+		if r.BlockIO.Weight != nil {
+			c.BlkioWeight = *r.BlockIO.Weight
+		}
+		if r.BlockIO.LeafWeight != nil {
+			c.BlkioLeafWeight = *r.BlockIO.LeafWeight
+		}
 	}
 	for _, wd := range r.BlockIO.WeightDevice {
 		weightDevice := configs.NewWeightDevice(wd.Major, wd.Minor, *wd.Weight, *wd.LeafWeight)
@@ -695,12 +701,14 @@ func (rt *libcontainerRuntime) createCgroupConfig(name string, spec *specs.Linux
 		})
 	}
 	c.OomKillDisable = r.DisableOOMKiller != nil && *r.DisableOOMKiller
-	c.NetClsClassid = r.Network.ClassID
-	for _, m := range r.Network.Priorities {
-		c.NetPrioIfpriomap = append(c.NetPrioIfpriomap, &configs.IfPrioMap{
-			Interface: m.Name,
-			Priority:  int64(m.Priority),
-		})
+	if r.Network != nil {
+		c.NetClsClassid = r.Network.ClassID
+		for _, m := range r.Network.Priorities {
+			c.NetPrioIfpriomap = append(c.NetPrioIfpriomap, &configs.IfPrioMap{
+				Interface: m.Name,
+				Priority:  int64(m.Priority),
+			})
+		}
 	}
 	return cr, nil
 }