linux-kernel - Forwarded: [PATCH] net: skbuff: fix uninitialized memory use in pskb_expand

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Message-ID: <69678d26.a70a0220.3ceeff.0000.GAE@google.com>
Date: Wed, 14 Jan 2026 04:33:42 -0800
From: syzbot <syzbot+619b9ef527f510a57cfc@...kaller.appspotmail.com>
To: linux-kernel@...r.kernel.org
Subject: Forwarded: [PATCH] net: skbuff: fix uninitialized memory use in pskb_expand_head()

For archival purposes, forwarding an incoming command email to
linux-kernel@...r.kernel.org.

***

Subject: [PATCH] net: skbuff: fix uninitialized memory use in pskb_expand_head()
Author: sohammetha01@...il.com

pskb_expand_head() allocates a new skb data buffer using
kmalloc_reserve(), which does not initialize memory. skb helpers may
later copy or move padding bytes from the buffer.

Initialize the newly allocated skb buffer to avoid propagating
uninitialized memory.

Reported-by: syzbot+619b9ef527f510a57cfc@...kaller.appspotmail.com
Signed-off-by: Soham Metha <sohammetha01@...il.com>
---
#syz test

 net/core/skbuff.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a56133902c0d..b0f0d3a0310b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -2282,6 +2282,9 @@ int pskb_expand_head(struct sk_buff *skb, int nhead, int ntail,
 	data = kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL);
 	if (!data)
 		goto nodata;
+
+	memset(data, 0, size);
+
 	size = SKB_WITH_OVERHEAD(size);
 
 	/* Copy only real data... and, alas, header. This should be
-- 
2.34.1