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SubjectRe: [PATCH net 2/3] bpf: fix splat for illegal devmap percpu allocation
On Tue, Oct 17, 2017 at 04:55:53PM +0200, Daniel Borkmann wrote:
> It was reported that syzkaller was able to trigger a splat on
> devmap percpu allocation due to illegal/unsupported allocation
> request size passed to __alloc_percpu():
>
> [ 70.094249] illegal size (32776) or align (8) for percpu allocation
> [ 70.094256] ------------[ cut here ]------------
> [ 70.094259] WARNING: CPU: 3 PID: 3451 at mm/percpu.c:1365 pcpu_alloc+0x96/0x630
> [...]
> [ 70.094325] Call Trace:
> [ 70.094328] __alloc_percpu_gfp+0x12/0x20
> [ 70.094330] dev_map_alloc+0x134/0x1e0
> [ 70.094331] SyS_bpf+0x9bc/0x1610
> [ 70.094333] ? selinux_task_setrlimit+0x5a/0x60
> [ 70.094334] ? security_task_setrlimit+0x43/0x60
> [ 70.094336] entry_SYSCALL_64_fastpath+0x1a/0xa5
>
> This was due to too large max_entries for the map such that we
> surpassed the upper limit of PCPU_MIN_UNIT_SIZE. It's fine to
> fail naturally here, so switch to __alloc_percpu_gfp() and pass
> __GFP_NOWARN instead.
>
> Fixes: 11393cc9b9be ("xdp: Add batching support to redirect map")
> Reported-by: Mark Rutland <mark.rutland@arm.com>
> Reported-by: Shankara Pailoor <sp3485@columbia.edu>
> Reported-by: Richard Weinberger <richard@nod.at>
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> Cc: John Fastabend <john.fastabend@gmail.com>

Acked-by: Alexei Starovoitov <ast@kernel.org>

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