CVE-2022-49889
ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()
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ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters()
In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Check for NULL cpu_buffer in ring_buffer_wake_waiters() On some machines the number of listed CPUs may be bigger than the actual CPUs that exist. The tracing subsystem allocates a per_cpu directory with access to the per CPU ring buffer via a cpuX file. But to save space, the ring buffer will only allocate buffers for online CPUs, even though the CPU array will be as big as the nr_cpu_ids. With the addition of waking waiters on the ring buffer when closing the file, the ring_buffer_wake_waiters() now needs to make sure that the buffer is allocated (with the irq_work allocated with it) before trying to wake waiters, as it will cause a NULL pointer dereference. While debugging this, I added a NULL check for the buffer itself (which is OK to do), and also NULL pointer checks against buffer->buffers (which is not fine, and will WARN) as well as making sure the CPU number passed in is within the nr_cpu_ids (which is also not fine if it isn't). Bugzilla: https://bugzilla.opensuse.org/show_bug.cgi?id=1204705
Reserved 2025-05-01 | Published 2025-05-01 | Updated 2025-05-04 | Assigner Linuxgit.kernel.org/...c/b5074df412bf3df9d6ce096b6fa03eb1082d05c9
git.kernel.org/...c/49ca992f6e50d0f46ec9608f44e011cf3121f389
git.kernel.org/...c/7433632c9ff68a991bd0bc38cabf354e9d2de410
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