From: Soham Metha <sohammetha01@gmail.com>
To: linux-kernel-mentees@lists.linuxfoundation.org
Cc: shuah@kernel.org,
syzbot+619b9ef527f510a57cfc@syzkaller.appspotmail.com,
syzkaller-bugs@googlegroups.com, andrii@kernel.org,
ast@kernel.org, bpf@vger.kernel.org, daniel@iogearbox.net,
eddyz87@gmail.com, haoluo@google.com, john.fastabend@gmail.com,
jolsa@kernel.org, kpsingh@kernel.org,
linux-kernel@vger.kernel.org, martin.lau@linux.dev,
sdf@fomichev.me, song@kernel.org, yonghong.song@linux.dev,
Soham Metha <sohammetha01@gmail.com>
Subject: [PATCH] net: skbuff: fix uninitialized memory use in pskb_expand_head()
Date: Wed, 14 Jan 2026 19:26:43 +0530 [thread overview]
Message-ID: <20260114135643.17484-1-sohammetha01@gmail.com> (raw)
In-Reply-To: <6954bc70.050a0220.a1b6.0310.GAE@google.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@syzkaller.appspotmail.com
Signed-off-by: Soham Metha <sohammetha01@gmail.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
next prev parent reply other threads:[~2026-01-14 13:57 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-12-31 6:02 [syzbot] [bpf?] KMSAN: uninit-value in bpf_prog_test_run_skb syzbot
2026-01-14 13:56 ` Soham Metha [this message]
2026-01-14 15:06 ` syzbot
2026-01-26 11:43 ` [PATCH v2] net: skbuff: fix uninitialized memory use in pskb_expand_head() Soham Metha
2026-01-26 13:26 ` Eric Dumazet
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