Fix memset past end of buffer in erpc_setup_mbf_static.cpp #184
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The memset of the m_buffers variable was not being done correctly. For example, consider: ERPC_DEFAULT_BUFFERS_COUNT=3 ERPC_DEFAULT_BUFFER_SIZE=24 ERPC_BUFFER_SIZE_UINT8 would be (24 + 8 - 1) = 31 ERPC_BUFFER_SIZE_UINT64 would be (31 / 8) = 3 The size of the memset would be (3 * 31) = 93 The size of the array would be (8 * 3 * 3) = 72 So in this example, the memset would go (93 - 72) = 21 bytes past the end of the array.
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I just came across this too, thanks for the PR. I think there's another bug in this code related to (void)memset(m_freeBufferBitmap, 0xff, ERPC_DEFAULT_BUFFERS_COUNT >> 3);Should be: (void)memset(m_freeBufferBitmap, 0xff, (ERPC_DEFAULT_BUFFERS_COUNT >> 3)+1U); // or sizeof(m_freeBufferBitmap)Since |
The array m_freeBufferBitmap was larger than necessary when ERPC_DEFAULT_BUFFERS_COUNT is divisible by 8. This is not a bug, but it is a bit inefficient. The memset of m_freeBufferBitmap was shorter than the length of the array which had the effect of pre-allocating (ERPC_DEFAULT_BUFFERS_COUNT % 8) of the buffers. Thanks to Peter Hinson for identifying this issue.
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Good point @peterhinson. I have added a second commit that I believe also addresses this issue. |
MichalPrincNXP
approved these changes
Jun 24, 2021
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Good point, great, thank you @dpfrey , @peterhinson . Again, because the internal testing for the v1.8.1 release is almost finished, I would rather integrate this PR after the release, i.e. in about 3w. Thank you. |
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Thanks a lot! |
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The memset of the m_buffers variable was not being done correctly.
For example, consider:
ERPC_DEFAULT_BUFFERS_COUNT=3
ERPC_DEFAULT_BUFFER_SIZE=24
ERPC_BUFFER_SIZE_UINT8 would be (24 + 8 - 1) = 31
ERPC_BUFFER_SIZE_UINT64 would be (31 / 8) = 3
The size of the memset would be (3 * 31) = 93
The size of the array would be (8 * 3 * 3) = 72
So in this example, the memset would go (93 - 72) = 21 bytes past the
end of the array.