bpf: Improve linked register tracking #10946
Closed
Conversation
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
Author
|
Upstream branch: f11f7cf |
kernel-patches-daemon-bpf
bot
force-pushed
the
bpf-next_base
branch
from
8d76c66 to
eec9a8d
Compare
Author
|
Upstream branch: b28dac3 |
… tracking Previously, the verifier only tracked positive constant deltas between linked registers using BPF_ADD. This limitation meant patterns like: r1 = r0; r1 += -4; if r1 s>= 0 goto l0_%=; // r1 >= 0 implies r0 >= 4 // verifier couldn't propagate bounds back to r0 if r0 != 0 goto l0_%=; r0 /= 0; // Verifier thinks this is reachable l0_%=: Similar limitation exists for 32-bit registers. With this change, the verifier can now track negative deltas in reg->off enabling bound propagation for the above pattern. For alu32, we make sure the destination register has the upper 32 bits as 0s before creating the link. BPF_ADD_CONST is split into BPF_ADD_CONST64 and BPF_ADD_CONST32, the latter is used in case of alu32 and sync_linked_regs uses this to zext the result if known_reg has this flag. Signed-off-by: Puranjay Mohan <[email protected]>
Add tests for linked register tracking with negative offsets, BPF_SUB, and alu32. These test for all edge cases like overflows, etc. Signed-off-by: Puranjay Mohan <[email protected]>
kernel-patches-daemon-bpf
bot
force-pushed
the
series/1050486=>bpf-next
branch
from
50b2538 to
cdbe18c
Compare
Author
|
At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=1050486 expired. Closing PR. |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
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Outdated suggestions cannot be applied.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.
Pull request for series with
subject: bpf: Improve linked register tracking
version: 3
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1050486