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SubjectRe: [PATCH AUTOSEL 5.13 13/14] net: fix NULL pointer reference in cipso_v4_doi_free
On Mon, Aug 30, 2021 at 8:01 PM Sasha Levin <sashal@kernel.org> wrote:
>
> From: 王贇 <yun.wang@linux.alibaba.com>
>
> [ Upstream commit 733c99ee8be9a1410287cdbb943887365e83b2d6 ]
>

Hi Sasha,

Michael Wang has sent a v2 patch [1] for this bug and it is merged
into netdev/net-next.git. However, the v1 patch is already in the
upstream tree.

How do you guys handle such a issue?

[1] https://lkml.org/lkml/2021/8/30/229

> In netlbl_cipsov4_add_std() when 'doi_def->map.std' alloc
> failed, we sometime observe panic:
>
> BUG: kernel NULL pointer dereference, address:
> ...
> RIP: 0010:cipso_v4_doi_free+0x3a/0x80
> ...
> Call Trace:
> netlbl_cipsov4_add_std+0xf4/0x8c0
> netlbl_cipsov4_add+0x13f/0x1b0
> genl_family_rcv_msg_doit.isra.15+0x132/0x170
> genl_rcv_msg+0x125/0x240
>
> This is because in cipso_v4_doi_free() there is no check
> on 'doi_def->map.std' when 'doi_def->type' equal 1, which
> is possibe, since netlbl_cipsov4_add_std() haven't initialize
> it before alloc 'doi_def->map.std'.
>
> This patch just add the check to prevent panic happen for similar
> cases.
>
> Reported-by: Abaci <abaci@linux.alibaba.com>
> Signed-off-by: Michael Wang <yun.wang@linux.alibaba.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
> Signed-off-by: Sasha Levin <sashal@kernel.org>
> ---
> net/ipv4/cipso_ipv4.c | 18 ++++++++++--------
> 1 file changed, 10 insertions(+), 8 deletions(-)
>
> diff --git a/net/ipv4/cipso_ipv4.c b/net/ipv4/cipso_ipv4.c
> index e0480c6cebaa..16bbd62db791 100644
> --- a/net/ipv4/cipso_ipv4.c
> +++ b/net/ipv4/cipso_ipv4.c
> @@ -466,14 +466,16 @@ void cipso_v4_doi_free(struct cipso_v4_doi *doi_def)
> if (!doi_def)
> return;
>
> - switch (doi_def->type) {
> - case CIPSO_V4_MAP_TRANS:
> - kfree(doi_def->map.std->lvl.cipso);
> - kfree(doi_def->map.std->lvl.local);
> - kfree(doi_def->map.std->cat.cipso);
> - kfree(doi_def->map.std->cat.local);
> - kfree(doi_def->map.std);
> - break;
> + if (doi_def->map.std) {
> + switch (doi_def->type) {
> + case CIPSO_V4_MAP_TRANS:
> + kfree(doi_def->map.std->lvl.cipso);
> + kfree(doi_def->map.std->lvl.local);
> + kfree(doi_def->map.std->cat.cipso);
> + kfree(doi_def->map.std->cat.local);
> + kfree(doi_def->map.std);
> + break;
> + }
> }
> kfree(doi_def);
> }
> --
> 2.30.2
>

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