http2: Safer invocation of populate_binsettings#12101
Closed
klyubin wants to merge 1 commit into
Closed
Conversation
populate_binsettings now returns a negative value on error, instead of a huge positive value. Both places which call this function have been updated to handle this change in its contract. The way populate_binsettings had been used prior to this change the huge positive values -- due to signed->unsigned conversion of the potentially negative result of nghttp2_pack_settings_payload which returns negative values on error -- are not possible. But only because http2.c currently always provides a large enough output buffer and provides H2 SETTINGS IVs which pass the verification logic inside nghttp2. If the verification logic were to change or if http2.c started passing in more IVs without increasing the output buffer size, the overflow could become reachable, and libcurl/curl might start leaking memory contents to servers/proxies...
klyubin
commented
Oct 12, 2023
| ssize_t binlen; /* length of the binsettings data */ | ||
|
|
||
| binlen = populate_binsettings(binsettings, data); | ||
| if(binlen <= 0) { |
Contributor
Author
There was a problem hiding this comment.
The check is <= 0 instead of < 0 to be consistent with the pre-existing such check in Curl_http2_request_upgrade (below)
Member
|
Thanks! |
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
populate_binsettings now returns a negative value on error, instead of a huge positive value. Both places which call this function have been updated to handle this change in its contract.
The way populate_binsettings had been used prior to this change the huge positive values -- due to signed->unsigned conversion of the potentially negative result of
nghttp2_pack_settings_payload which returns negative values on error -- are not possible. But only because http2.c currently always provides a large enough output buffer and provides H2 SETTINGS IVs which pass the verification logic inside nghttp2. If the verification logic were to change or if http2.c started passing in more IVs without increasing the output buffer size, the overflow could become reachable, and libcurl/curl might start leaking memory contents to servers/proxies...