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([103.182.158.108]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-35109e7ee68sm2101653a91.17.2026.01.14.05.56.53 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 14 Jan 2026 05:57:00 -0800 (PST) From: Soham Metha 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 Subject: [PATCH] net: skbuff: fix uninitialized memory use in pskb_expand_head() Date: Wed, 14 Jan 2026 19:26:43 +0530 Message-Id: <20260114135643.17484-1-sohammetha01@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <6954bc70.050a0220.a1b6.0310.GAE@google.com> References: <6954bc70.050a0220.a1b6.0310.GAE@google.com> 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" 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 Tested-by: syzbot+619b9ef527f510a57cfc@syzkaller.appspotmail.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 =3D kmalloc_reserve(&size, gfp_mask, NUMA_NO_NODE, NULL); if (!data) goto nodata; + + memset(data, 0, size); + size =3D SKB_WITH_OVERHEAD(size); =20 /* Copy only real data... and, alas, header. This should be --=20 2.34.1