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From: Kuniyuki Iwashima To: Petko Manolov , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: Kuniyuki Iwashima , Kuniyuki Iwashima , netdev@vger.kernel.org, linux-usb@vger.kernel.org, syzbot+b4d5d8faea6996fd55e3@syzkaller.appspotmail.com Content-Type: text/plain; charset="UTF-8" syzbot reported set_carrier() accesses an uninitialised local var. [0] get_registers() is a wrapper of usb_control_msg_recv(), which copies data to the passed buffer only when it returns 0. Let's check the retval before accessing tmp in set_carrier(). [0]: BUG: KMSAN: uninit-value in set_carrier drivers/net/usb/rtl8150.c:721 [inline] BUG: KMSAN: uninit-value in rtl8150_open+0x1131/0x1360 drivers/net/usb/rtl8150.c:758 set_carrier drivers/net/usb/rtl8150.c:721 [inline] rtl8150_open+0x1131/0x1360 drivers/net/usb/rtl8150.c:758 __dev_open+0x7e9/0xc60 net/core/dev.c:1682 __dev_change_flags+0x3a8/0x9f0 net/core/dev.c:9549 netif_change_flags+0x8d/0x1e0 net/core/dev.c:9612 dev_change_flags+0x18c/0x320 net/core/dev_api.c:68 devinet_ioctl+0x1186/0x2500 net/ipv4/devinet.c:1200 inet_ioctl+0x4c0/0x6f0 net/ipv4/af_inet.c:1001 sock_do_ioctl+0x9c/0x480 net/socket.c:1238 sock_ioctl+0x70b/0xd60 net/socket.c:1359 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0x23c/0x400 fs/ioctl.c:584 __x64_sys_ioctl+0x97/0xe0 fs/ioctl.c:584 x64_sys_call+0x1cbc/0x3e20 arch/x86/include/generated/asm/syscalls_64.h:17 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xd9/0x210 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f Local variable tmp created at: number+0x8a/0x2200 lib/vsprintf.c:469 vsnprintf+0xd21/0x1bd0 lib/vsprintf.c:2890 CPU: 1 UID: 0 PID: 5461 Comm: dhcpcd Not tainted syzkaller #0 PREEMPT(none) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: syzbot+b4d5d8faea6996fd55e3@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/68af933a.a00a0220.2929dc.0007.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima --- drivers/net/usb/rtl8150.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c index ddff6f19ff98..0f45627f6a00 100644 --- a/drivers/net/usb/rtl8150.c +++ b/drivers/net/usb/rtl8150.c @@ -717,8 +717,8 @@ static void set_carrier(struct net_device *netdev) rtl8150_t *dev = netdev_priv(netdev); short tmp; - get_registers(dev, CSCR, 2, &tmp); - if (tmp & CSCR_LINK_STATUS) + if (!get_registers(dev, CSCR, 2, &tmp) && + (tmp & CSCR_LINK_STATUS)) netif_carrier_on(netdev); else netif_carrier_off(netdev); -- 2.51.0.268.g9569e192d0-goog