CVE-2026-98777: binder: fix leaked fd fixups on TF_UPDATE_TXN supersede
In the Linux kernel, the following vulnerability has been resolved:
binder: fix leaked fd fixups on TFUPDATETXN supersede
When a TFUPDATETXN transaction supersedes a pending async transaction in a frozen process, the outdated transaction is freed with kfree() directly. This skips binderfreetxnfixups(), leaking all bindertxnfdfixup entries and their fget()'d struct file references.
The leaked file refcounts never reach zero, so the struct file objects are permanently pinned in memory. They survive process exit and accumulate across invocations until file-max exhaustion.
Every other transaction cleanup path (binderfreetransaction(), bindertransaction() error paths, binderreleasework()) correctly calls binderfreetxnfixups(). Add the missing call before kfree() in the toutdated cleanup block.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
In the t_outdated cleanup block of binder_transaction(), call binder_free_txn_fixups() before kfree() so leaked binder_txn_fd_fixup entries and their fget()'d struct file references are released when a TF_UPDATE_TXN transaction supersedes a pending async transaction.