Conversation
ima_ng_show() already rejects a digest field longer than the remaining template data. A zero length still passes that test: field_len - 1 wraps to UINT32_MAX and is passed to strnlen(), which reads past the template buffer. Subtracting that length from field_len can wrap as well. Require a non-zero digest field before using field_len - 1 as the strnlen() limit. strnlen() then returns at most field_len - 1, so the existing field_len - len subtraction stays in range. Signed-off-by: Evgeniy Gorbanyov <esgor@altlinux.org>
Collaborator
|
This patch looks good. Could you fix the other field_len usage as well, maybe as a separate patch. |
Author
|
The remaining total_len < field_len checks are for the signature and ima-buf fields. A zero length is valid there: it means the signature or buffer is absent. Both paths already skip the field when field_len is 0, so the length is not used in pointer or size arithmetic. |
This file contains hidden or 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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
2 participants
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
ima_ng_show() already rejects a digest field longer than the remaining template data. A zero length still passes that test: field_len - 1 wraps to UINT32_MAX and is passed to strnlen(), which reads past the template buffer. Subtracting that length from field_len can wrap as well.
Require a non-zero digest field before using field_len - 1 as the strnlen() limit. strnlen() then returns at most field_len - 1, so the existing field_len - len subtraction stays in range.