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ukvm: Multiple issues with ELF loader #126

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mato opened this issue Nov 22, 2016 · 2 comments
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ukvm: Multiple issues with ELF loader #126

mato opened this issue Nov 22, 2016 · 2 comments
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mato commented Nov 22, 2016

While reviewing #123 and trying to write a test to go into tests/ for #73 I found (at least) the following issues with the ELF loader in ukvm:

  1. In load_code() the test for a loadable segment is incorrect, phdr.p_type is not a bitmap.
  2. Return values from mprotect() are not checked.
  3. The mprotect() call which is supposed to write-protect .text is passed a len which is not a multiple of the page size.
  4. (related) Trying to write to a global char * in the guest produces an EFAULT exit from KVM_RUN where it should succeed.

I'm working on auditing that code and fixing the above.
@mato mato added the bug label Nov 22, 2016
@mato mato self-assigned this Nov 22, 2016
@mato mato mentioned this issue Nov 22, 2016
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mato added a commit to mato/solo5 that referenced this issue Nov 23, 2016
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ukvm: Audit ELF loader
8bbb81b 
General cleanup and audit in load_code().  Fixes Solo5#126, removes
unnecessary casts and verifies that the load address/sizes in program
header are valid.

The guard page at the end of the last loaded segment is removed; it
didn't serve any useful function.
@mato mato mentioned this issue Nov 23, 2016
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@mato mato closed this as completed in #127 Nov 23, 2016
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mato commented Nov 23, 2016

Not quite done yet, need to address #127 (comment)

@mato mato reopened this Nov 23, 2016
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mato commented Nov 28, 2016

With #129 merged, this is done now.

@mato mato closed this as completed Nov 28, 2016
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