Re: [PATCH 01/13] bpf: Guard against accessing NULL pt_regs in bpf_get_task_stack()

[Daniel Borkmann]

On 1/6/22 12:45 PM, Naveen N. Rao wrote:

task_pt_regs() can return NULL on powerpc for kernel threads. This is
then used in __bpf_get_stack() to check for user mode, resulting in a
kernel oops. Guard against this by checking return value of
task_pt_regs() before trying to obtain the call chain.

Fixes: fa28dcb82a38f8 ("bpf: Introduce helper bpf_get_task_stack()")
Cc: sta...@vger.kernel.org # v5.9+
Signed-off-by: Naveen N. Rao <naveen.n....@linux.vnet.ibm.com>

Acked-by: Daniel Borkmann <dan...@iogearbox.net>