Repository navigation
consume %c argument in cupsFormatStringv when buffer is full - #201
Closed
tanjiroK-coder wants to merge 1 commit into
Closed
tanjiroK-coder wants to merge 1 commit into
tanjiroK-coder wants to merge 1 commit into
Conversation
michaelrsweet
requested changes
Oct 29, 2026
michaelrsweet
left a comment
michaelrsweet
left a comment
Member
There was a problem hiding this comment.
This change is far too intrusive. Will push a simpler change and without another unit test for this edge case.
michaelrsweet
added a commit
that referenced
this pull request
Oct 29, 2026
Contributor
Author
|
thanks, 416b035 keeps it a lot smaller than mine did. closing this one. |
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
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Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be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.
Dropped
%cargument in cupsFormatStringvWhen the output buffer is already full, the
%ccase returns without callingva_arg, so every later conversion reads one argument too early; a%cfollowed by%sor%pthen treats a non-pointer value as a pointer and dereferences it.cupsFormatString/cupsFormatStringvare public, so any caller that puts%cbefore another conversion with runtime data long enough to fill the buffer is affected.Reproduced under AddressSanitizer with
cupsFormatString(buf, 2, "X%c%s", 'A', "hello"), which faults with a read at address 0x41 in string.c. The newcups/teststring.cchecks that the returned length does not depend on the output buffer size; it fails before this change and passes after.