gnrc_ipv6_ext: don't read from pkt->data after _demux()
#11580
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
miri64
added
Type: bug
`_demux()` might change `pkt->data` in all kind of ways (moving it due to `gnrc_pktbuf_mark()`, though unlikely; releasing it, because e.g. it starts with a fragment header that marks a fragmented packet containing only one fragment, etc.) so accessing the pointer *after* calling `_demux()` is somewhat playing with fire. This change avoids this by storing the value of `ext_hdr->nh` (all we are interested in here) in a temporary variable that then is used to set the out-parameter `nh`. `protnum` needs to be unchanged before the call to `_demux()` as it was set by the previous iteration and determines what extension header actually is handled.
miri64
force-pushed
the
gnrc_ipv6_ext/fix/nh-after-change
branch
from
d9089bd
to
ea1708b
Compare
kaspar030
added
the
CI: ready for build
kaspar030
approved these changes
May 25, 2019
only on master? 🤨 |
nah, tested on native. 😉 |
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Outdated suggestions cannot be applied.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.
Contribution description
_demux()might changepkt->datain all kind of ways (moving it dueto
gnrc_pktbuf_mark(), though unlikely; releasing it, because e.g. itstarts with a fragment header that marks a fragmented packet containing
only one fragment, etc.) so accessing the pointer after calling
_demux()is somewhat playing with fire. This change avoids this bystoring the value of
ext_hdr->nh(all we are interested in here) in atemporary variable that then is used to set the out-parameter
nh.protnumneeds to be unchanged before the call to_demux()as it wasset by the previous iteration and determines what extension header
actually is handled (this is why a temporary variable is needed and we
can't just set
*protnum).Testing procedure
should still pass.
Issues/PRs references
None.