From 1a30cb31452a17a5e039fb36d8e168c72a36edf6 Mon Sep 17 00:00:00 2001 From: Qingfang Deng Date: Fri, 26 Sep 2025 18:18:59 +0800 Subject: [PATCH] ppp: fix memory leak in pad_compress_skb stable inclusion from stable-v6.6.105 commit 85c1c86a67e09143aa464e9bf09c397816772348 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/ICYXVZ CVE: CVE-2025-39847 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=85c1c86a67e09143aa464e9bf09c397816772348 -------------------------------- [ Upstream commit 4844123fe0b853a4982c02666cb3fd863d701d50 ] If alloc_skb() fails in pad_compress_skb(), it returns NULL without releasing the old skb. The caller does: skb = 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 Link: https://patch.msgid.link/20250903100726.269839-1-dqfext@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin Signed-off-by: Zhang Changzhong --- 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 ee1527cf3d0c..abe6a5ecd772 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -1749,7 +1749,6 @@ 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 = NULL; } @@ -1851,9 +1850,10 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb) "down - pkt dropped.\n"); goto drop; } - skb = pad_compress_skb(ppp, skb); - if (!skb) + new_skb = pad_compress_skb(ppp, skb); + if (!new_skb) goto drop; + skb = new_skb; } /* -- Gitee