Description
In the Linux kernel, the following vulnerability has been resolved: cnic: Fix use-after-free bugs in cnic_delete_task The original code uses cancel_delayed_work() in cnic_cm_stop_bnx2x_hw(), which does not guarantee that the delayed work item 'delete_task' has fully completed if it was already running. Additionally, the delayed work item is cyclic, the flush_workqueue() in cnic_cm_stop_bnx2x_hw() only blocks and waits for work items that were already queued to the workqueue prior to its invocation. Any work items submitted after flush_workqueue() is called are not included in the set of tasks that the flush operation awaits. This means that after the cyclic work items have finished executing, a delayed work item may still exist in the workqueue. This leads to use-after-free scenarios where the cnic_dev is deallocated by cnic_free_dev(), while delete_task remains active and attempt to dereference cnic_dev in cnic_delete_task(). A typical race condition is illustrated below: CPU 0 (cleanup) | CPU 1 (delayed work callback) cnic_netdev_event() | cnic_stop_hw() | cnic_delete_task() cnic_cm_stop_bnx2x_hw() | ... cancel_delayed_work() | /* the queue_delayed_work() flush_workqueue() | executes after flush_workqueue()*/ | queue_delayed_work() cnic_free_dev(dev)//free | cnic_delete_task() //new instance | dev = cp->dev; //use Replace cancel_delayed_work() with cancel_delayed_work_sync() to ensure that the cyclic delayed work item is properly canceled and that any ongoing execution of the work item completes before the cnic_dev is deallocated. Furthermore, since cancel_delayed_work_sync() uses __flush_work(work, true) to synchronously wait for any currently executing instance of the work item to finish, the flush_workqueue() becomes redundant and should be removed. This bug was identified through static analysis. To reproduce the issue and validate the fix, I simulated the cnic PCI device in QEMU and introduced intentional delays — such as inserting calls to ssleep() within the cnic_delete_task() function — to increase the likelihood of triggering the bug.
Product status
fdf24086f4752aee5dfb40143c736250df017820 before fde6e73189f40ebcf0633aed2b68e731c25f3aa3
fdf24086f4752aee5dfb40143c736250df017820 before 7b6a5b0a6b392263c3767fc945b311ea04b34bbd
fdf24086f4752aee5dfb40143c736250df017820 before 0405055930264ea8fd26f4131466fa7652e5e47d
fdf24086f4752aee5dfb40143c736250df017820 before e1fcd4a9c09feac0902a65615e866dbf22616125
fdf24086f4752aee5dfb40143c736250df017820 before 8eeb2091e72d75df8ceaa2172638d61b4cf8929a
fdf24086f4752aee5dfb40143c736250df017820 before 6e33a7eed587062ca8161ad1f4584882a860d697
fdf24086f4752aee5dfb40143c736250df017820 before 0627e1481676669cae2df0d85b5ff13e7d24c390
fdf24086f4752aee5dfb40143c736250df017820 before cfa7d9b1e3a8604afc84e9e51d789c29574fb216
2.6.37
Any version before 2.6.37
5.4.300
5.10.245
5.15.194
6.1.154
6.6.108
6.12.49
6.16.9
6.17
References
git.kernel.org/...c/fde6e73189f40ebcf0633aed2b68e731c25f3aa3
git.kernel.org/...c/7b6a5b0a6b392263c3767fc945b311ea04b34bbd
git.kernel.org/...c/0405055930264ea8fd26f4131466fa7652e5e47d
git.kernel.org/...c/e1fcd4a9c09feac0902a65615e866dbf22616125
git.kernel.org/...c/8eeb2091e72d75df8ceaa2172638d61b4cf8929a
git.kernel.org/...c/6e33a7eed587062ca8161ad1f4584882a860d697
git.kernel.org/...c/0627e1481676669cae2df0d85b5ff13e7d24c390
git.kernel.org/...c/cfa7d9b1e3a8604afc84e9e51d789c29574fb216
