Fix crashes/freezes in VSS stripping code #913
Merged
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
When VSS header data straddles multiple network blocks (i.e. got < bsidsize in bfile_write_vss_strip()), the pointer arithmatic when memcpy()ing the next block is incorrect. Since sid is a pointer to a structure, each addition by 1 increases the pointer address by sizeof(*sid); therefore, when sidlen > 0, the memcpy() unintentionally overwrites part of the struct BFILE it lives within or the memory situated after it. Casting sid to a char* in the memcpy() causes the addition to advance the pointer by single bytes as intended.
When stripping VSS data, an empty stream that has additional data following it will currently cause an infinite loop in bfile_write_vss_strip(). When encountering an empty stream, attempt to start reading a new VSS header instead.
|
Hello, thanks for this, I will check it soon. |
|
This patch doesn't break any of my automated tests, and looks fine to me, so happily merged. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
Greetings,
I ran into a couple of issues while attempting to restore a large backup from a Windows host with VSS stripping enabled:
There are some more details in the commit messages.
As far as I can tell, bfile_write_vss_strip() and the vss_strip tool do not properly support sparse files and will only write sections with type 1 to disk, but with these fixes I can at least restore my backup and address the sparse files some other way if needed. I couldn't easily find the information I'd need to implement -x for BACKUP_SPARSE_BLOCK (type 9), but I'm sure I'm preaching to the choir there.
I discovered issue #895 while researching my problems, and I suspect that issue was caused either by the first bug or the lack of sparse file support.
Cheers!