5.4-stable review patch. If anyone has any objections, please let me know.
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From: Qingfang Deng dqfext@gmail.com
[ 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 dqfext@gmail.com Reviewed-by: Eric Dumazet edumazet@google.com Reviewed-by: Yue Haibing yuehaibing@huawei.com Link: https://patch.msgid.link/20250903100726.269839-1-dqfext@gmail.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 7b9337e16d6e1..dd7c84e4b4986 100644 --- a/drivers/net/ppp/ppp_generic.c +++ b/drivers/net/ppp/ppp_generic.c @@ -1528,7 +1528,6 @@ 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; } @@ -1630,9 +1629,10 @@ 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; }
/*