Fix access violation exception that can occur during invocation of loop lambda function when inner_start >= inner_end in 'For' template. #3936
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
…datasets. Prior to this change, the line "score_t threshold = tmp_gradients[top_k - 1];" would generate an exception, since tmp_gradients would be empty when the cnt input value to the function is zero.
…data set given as of array of pointers to rows (as opposed to existing method LGBM_BoosterPredictForMat which requires data given as contiguous array)
…op lambda function when inner_start >= inner_end in 'For' template.
In particular, this can occur in Tree::AddPredictionToScore on line 291 where the loop lambda function body (created by the PredictionFun macro) dereferences used_data_indices[start].
For reference, the particular case which triggered this exception in my case was:
* start = 0
* end = 93,203
* n_block = 56
* min_block_size = 512
for which the BlockInfo method gave:
* n_block = 56
* num_inner = 1,696
and so, for the case i=55 (i.e., the last case in the loop), we get
* inner_start = start + num_inner * i
= 93,280
which is greater than 'end' and hence triggers the exception.
|
cc @shiyu1994 |
StrikerRUS
reviewed
Feb 12, 2021
|
I've checked all the |
|
This pull request has been automatically locked since there has not been any recent activity since it was closed. To start a new related discussion, open a new issue at https://github.com/microsoft/LightGBM/issues including a reference to this. |
Sign up for free
to subscribe to this conversation on GitHub.
Already have an account?
Sign in.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In particular, this can occur in
Tree::AddPredictionToScoreon line 291 of src\io\tree.cpp where the loop lambda function body (created by thePredictionFunmacro) dereferencesused_data_indices[start].For reference, the particular case which triggered this exception in my case was:
start= 0end= 93,203min_block_size= 512for which the
BlockInfomethod gave:n_block= 56num_inner= 1,696and so, for the case
i=55(i.e., the last case in the loop), we getinner_start = start + num_inner * i= 93,280which is greater than 'end' and hence triggers the exception.