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31 lines
1.3 KiB
31 lines
1.3 KiB
4 months ago
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Tests the fix for b/74116990
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The JIT was reading into incorrect dex files during class redefinition if a
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native method was present.
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The transformed dex file is specifically crafted to have exactly 4 methodIDs in
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it. They are (in order):
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(0) Ljava/lang/Object;-><init>()V
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(1) Lxyz/Transform;-><init>()V
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(2) Lxyz/Transform;->bar()V
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(3) Lxyz/Transform;->foo()V
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In the transformed version of the dex file there is a new method. The new list of methodIDs is:
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(0) Lart/Test1949;->doNothing()V
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(1) Ljava/lang/Object;-><init>()V
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(2) Lxyz/Transform;-><init>()V
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(3) Lxyz/Transform;->bar()V
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(4) Lxyz/Transform;->foo()V
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This test tries to get the JIT to read out-of-bounds on the initial dex file by getting it to
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read the 5th method id of the new file (Lxyz/Transform;->foo()V) from the old dex file (which
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only has 4 method ids).
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To do this we need to make sure that the class being transformed is near the end of the
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alphabet (package xyz, method foo). If it is further forward than the other method-ids then the
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JIT will read an incorrect (but valid) method-id from the old-dex file. This is why the error
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wasn't caught in our other tests (package art is always at the front).
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The final method that causes the OOB read needs to be a native method because that is the only
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method-type the jit uses dex-file information to keep track of.
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