exec: expose memory size to Process #149

laizy · 2019-07-30T10:15:08Z

we current has some host function like:

func HostFunc(proc *exec.Process, keyPtr uint32, keylen uint32) {
	keybytes := make([]byte, keylen) 
	_, err := proc.ReadAt(keybytes, int64(keyPtr))
       ...
}

vicious wasm code can provide a large keylen to make the bytes allocation failed. Expose the current memory size can let us prevent this attack by checking keyPtr + keylen <= MemSize

sbinet

nitpick then LGTM.

(thanks!)

sbinet · 2019-07-30T10:46:11Z

exec/vm.go

@@ -531,6 +531,11 @@ func (proc *Process) WriteAt(p []byte, off int64) (int, error) {
 	return length, err
 }

+// MemSize returns the current allocated memory size in bytes


s/in bytes/in bytes./

codecov-io · 2019-07-30T10:54:27Z

Codecov Report

Merging #149 into master will decrease coverage by 0.02%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master     #149      +/-   ##
==========================================
- Coverage   69.47%   69.44%   -0.03%     
==========================================
  Files          43       43              
  Lines        4921     4923       +2     
==========================================
  Hits         3419     3419              
- Misses       1217     1219       +2     
  Partials      285      285

Impacted Files	Coverage Δ
exec/vm.go	`83.27% <0%> (-0.6%)`	⬇️

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laizy force-pushed the wagon branch from 2efd30b to f07fba2 Compare July 30, 2019 10:17

sbinet reviewed Jul 30, 2019

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exec: expose memory size to Process

c8ed6c5

laizy force-pushed the wagon branch from f07fba2 to c8ed6c5 Compare July 30, 2019 10:52

sbinet approved these changes Jul 30, 2019

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sbinet merged commit 5a639f0 into go-interpreter:master Jul 30, 2019

laizy deleted the wagon branch July 30, 2019 12:51

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exec: expose memory size to Process #149

exec: expose memory size to Process #149

laizy commented Jul 30, 2019

sbinet left a comment

sbinet Jul 30, 2019

laizy Jul 30, 2019

codecov-io commented Jul 30, 2019 •

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exec: expose memory size to Process #149

exec: expose memory size to Process #149

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