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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Paul Mackerras , Matt Domsch , Andrew Morton , Brice Goglin , linux-ppp@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net] ppp: fix memory leak in pad_compress_skb Date: Wed, 3 Sep 2025 18:07:26 +0800 Message-ID: <20250903100726.269839-1-dqfext@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" If alloc_skb() fails in pad_compress_skb(), it returns NULL without releasing the old skb. The caller does: skb =3D pad_compress_skb(ppp, skb); if (!skb) goto drop; drop: kfree_skb(skb); When pad_compress_skb() returns NULL, the reference to the old skb is lost and kfree_skb(skb) ends up doing nothing, leading to a memory leak. Align pad_compress_skb() semantics with realloc(): only free the old skb if allocation and compression succeed. At the call site, use the new_skb variable so the original skb is not lost when pad_compress_skb() fails. Fixes: b3f9b92a6ec1 ("[PPP]: add PPP MPPE encryption module") Signed-off-by: Qingfang Deng Reviewed-by: Eric Dumazet Reviewed-by: Yue Haibing --- drivers/net/ppp/ppp_generic.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/net/ppp/ppp_generic.c b/drivers/net/ppp/ppp_generic.c index 65795d099166..f9f0f16c41d1 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -1744,7 +1744,6 @@ pad_compress_skb(struct ppp *ppp, struct sk_buff *skb) */ if (net_ratelimit()) netdev_err(ppp->dev, "ppp: compressor dropped pkt\n"); - kfree_skb(skb); consume_skb(new_skb); new_skb =3D NULL; } @@ -1845,9 +1844,10 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb) "down - pkt dropped.\n"); goto drop; } - skb =3D pad_compress_skb(ppp, skb); - if (!skb) + new_skb =3D pad_compress_skb(ppp, skb); + if (!new_skb) goto drop; + skb =3D new_skb; } =20 /* --=20 2.43.0