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Alexei Starovoitov authored
Fix the following issue: [ 436.749342] BUG: KASAN: use-after-free in bpf_trampoline_put+0x39/0x2a0 [ 436.749995] Write of size 4 at addr ffff8881ef38b8a0 by task kworker/3:5/2243 [ 436.750712] [ 436.752677] Workqueue: events bpf_prog_free_deferred [ 436.753183] Call Trace: [ 436.756483] bpf_trampoline_put+0x39/0x2a0 [ 436.756904] bpf_prog_free_deferred+0x16d/0x3d0 [ 436.757377] process_one_work+0x94a/0x15b0 [ 436.761969] [ 436.762130] Allocated by task 2529: [ 436.763323] bpf_trampoline_lookup+0x136/0x540 [ 436.763776] bpf_check+0x2872/0xa0a8 [ 436.764144] bpf_prog_load+0xb6f/0x1350 [ 436.764539] __do_sys_bpf+0x16d7/0x3720 [ 436.765825] [ 436.765988] Freed by task 2529: [ 436.767084] kfree+0xc6/0x280 [ 436.767397] bpf_trampoline_put+0x1fd/0x2a0 [ 436.767826] bpf_check+0x6832/0xa0a8 [ 436.768197] bpf_prog_load+0xb6f/0x1350 [ 436.768594] __do_sys_bpf+0x16d7/0x3720 prog->aux->trampoline = tr should be set only when prog is valid. Otherwise prog freeing will try to put trampoline via prog->aux->trampoline, but it may not point to a valid trampoline. Fixes: 6ba43b76 ("bpf: Attachment verification for BPF_MODIFY_RETURN") Signed-off-by:
Alexei Starovoitov <ast@kernel.org> Signed-off-by:
Daniel Borkmann <daniel@iogearbox.net> Acked-by:
KP Singh <kpsingh@google.com> Link: https://lore.kernel.org/bpf/20200529043839.15824-2-alexei.starovoitov@gmail.com
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