CVE-2021-47081

In the Linux kernel, the following vulnerability has been resolved:

habanalabs/gaudi: Fix a potential use after free in gaudi_memset_device_memory

Our code analyzer reported a uaf.

In gaudi_memset_device_memory, cb is get via hl_cb_kernel_create() with 2 refcount. If hl_cs_allocate_job() failed, the execution runs into release_cb branch. One ref of cb is dropped by hl_cb_put(cb) and could be freed if other thread also drops one ref. Then cb is used by cb->id later, which is a potential uaf.

My patch add a variable 'id' to accept the value of cb->id before the hl_cb_put(cb) is called, to avoid the potential uaf.