bpf: prevent nesting overflow in bpf_try_get_buffers #10278
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
bpf_try_get_buffers() returns one of multiple per-CPU buffers based on a per-CPU nesting counter. This mechanism expects that buffers are not endlessly acquired before being returned. migrate_disable() ensures that a task remains on the same CPU, but it does not prevent the task from being preempted by another task on that CPU. Without disabled preemption, a task may be preempted while holding a buffer, allowing another task to run on same CPU and acquire an additional buffer. Several such preemptions can cause the per-CPU nest counter to exceed MAX_BPRINTF_NEST_LEVEL and trigger the warning in bpf_try_get_buffers(). Adding preempt_disable()/preempt_enable() around buffer acquisition and release prevents this task preemption and preserves the intended bounded nesting behavior. Reported-by: [email protected] Closes: https://lore.kernel.org/all/[email protected]/ Fixes: 4223bf8 ("bpf: Remove preempt_disable in bpf_try_get_buffers") Suggested-by: Yonghong Song <[email protected]> Reviewed-by: Sebastian Andrzej Siewior <[email protected]> Signed-off-by: Sahil Chandna <[email protected]>
Author
|
Upstream branch: 93ce3be |
kernel-patches-daemon-bpf
bot
force-pushed
the
bpf-next_base
branch
from
4752827 to
05f2f03
Compare
Author
|
At least one diff in series https://patchwork.kernel.org/project/netdevbpf/list/?series=1023332 irrelevant now. Closing PR. |
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Outdated suggestions cannot be applied.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.
Pull request for series with
subject: bpf: prevent nesting overflow in bpf_try_get_buffers
version: 3
url: https://patchwork.kernel.org/project/netdevbpf/list/?series=1023332