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Thu, 23 Apr 2026 12:21:15 -0700 (PDT) Received: from LAPTOP-97G9G880.bbrouter ([106.51.151.135]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-36141898ebasm21101867a91.7.2026.04.23.12.21.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 23 Apr 2026 12:21:15 -0700 (PDT) From: root X-Google-Original-From: root To: joel@jms.id.au, andrew@codeconstruct.com.au Cc: jdelvare@suse.de, linux-aspeed@lists.ozlabs.org, linux-kernel@vger.kernel.org, Karthikeyan KS , stable@vger.kernel.org Subject: [PATCH] soc: aspeed: lpc-snoop: Fix usercopy overflow in snoop_file_read Date: Thu, 23 Apr 2026 19:20:45 +0000 Message-ID: <20260423192045.5729-1-root@LAPTOP-97G9G880.localdomain> X-Mailer: git-send-email 2.43.0 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" From: Karthikeyan KS snoop_file_read() passes the userspace count directly to kfifo_to_user() without clamping. The kfifo backing buffer is 2048 bytes (SNOOP_FIFO_SIZE), allocated from kmalloc-2k slab. A read larger than 2048 bytes triggers a BUG under CONFIG_HARDENED_USERCOPY: kernel BUG at mm/usercopy.c:99! Reproducer: hexdump /dev/aspeed-lpc-snoop0 Fix by clamping count to SNOOP_FIFO_SIZE before the copy. Fixes: 3772e5da4454 ("drivers/misc: Aspeed LPC snoop output using misc char= dev") Cc: stable@vger.kernel.org Signed-off-by: Karthikeyan KS --- drivers/soc/aspeed/aspeed-lpc-snoop.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/asp= eed-lpc-snoop.c index b03310c0830d..5b59e826cc68 100644 --- a/drivers/soc/aspeed/aspeed-lpc-snoop.c +++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c @@ -125,6 +125,7 @@ static ssize_t snoop_file_read(struct file *file, char = __user *buffer, if (ret =3D=3D -ERESTARTSYS) return -EINTR; } + count =3D min(count, (size_t)SNOOP_FIFO_SIZE); ret =3D kfifo_to_user(&chan->fifo, buffer, count, &copied); if (ret) return ret; --=20 2.34.1