| Message ID | 20230502122050.917205-1-idosch@nvidia.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 9ad685dbfe7e856bbf17a7177b64676d324d6ed7 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] ethtool: Fix uninitialized number of lanes | expand |
On Tue, May 02, 2023 at 03:20:50PM +0300, Ido Schimmel wrote: > It is not possible to set the number of lanes when setting link modes > using the legacy IOCTL ethtool interface. Since 'struct > ethtool_link_ksettings' is not initialized in this path, drivers receive > an uninitialized number of lanes in 'struct > ethtool_link_ksettings::lanes'. > > When this information is later queried from drivers, it results in the > ethtool code making decisions based on uninitialized memory, leading to > the following KMSAN splat [1]. In practice, this most likely only > happens with the tun driver that simply returns whatever it got in the > set operation. > > As far as I can tell, this uninitialized memory is not leaked to user > space thanks to the 'ethtool_ops->cap_link_lanes_supported' check in > linkmodes_prepare_data(). > > Fix by initializing the structure in the IOCTL path. Did not find any > more call sites that pass an uninitialized structure when calling > 'ethtool_ops::set_link_ksettings()'. > > [1] > BUG: KMSAN: uninit-value in ethnl_update_linkmodes net/ethtool/linkmodes.c:273 [inline] > BUG: KMSAN: uninit-value in ethnl_set_linkmodes+0x190b/0x19d0 net/ethtool/linkmodes.c:333 > ethnl_update_linkmodes net/ethtool/linkmodes.c:273 [inline] > ethnl_set_linkmodes+0x190b/0x19d0 net/ethtool/linkmodes.c:333 > ethnl_default_set_doit+0x88d/0xde0 net/ethtool/netlink.c:640 > genl_family_rcv_msg_doit net/netlink/genetlink.c:968 [inline] > genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline] > genl_rcv_msg+0x141a/0x14c0 net/netlink/genetlink.c:1065 > netlink_rcv_skb+0x3f8/0x750 net/netlink/af_netlink.c:2577 > genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076 > netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] > netlink_unicast+0xf41/0x1270 net/netlink/af_netlink.c:1365 > netlink_sendmsg+0x127d/0x1430 net/netlink/af_netlink.c:1942 > sock_sendmsg_nosec net/socket.c:724 [inline] > sock_sendmsg net/socket.c:747 [inline] > ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501 > ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555 > __sys_sendmsg net/socket.c:2584 [inline] > __do_sys_sendmsg net/socket.c:2593 [inline] > __se_sys_sendmsg net/socket.c:2591 [inline] > __x64_sys_sendmsg+0x36b/0x540 net/socket.c:2591 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > Uninit was stored to memory at: > tun_get_link_ksettings+0x37/0x60 drivers/net/tun.c:3544 > __ethtool_get_link_ksettings+0x17b/0x260 net/ethtool/ioctl.c:441 > ethnl_set_linkmodes+0xee/0x19d0 net/ethtool/linkmodes.c:327 > ethnl_default_set_doit+0x88d/0xde0 net/ethtool/netlink.c:640 > genl_family_rcv_msg_doit net/netlink/genetlink.c:968 [inline] > genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline] > genl_rcv_msg+0x141a/0x14c0 net/netlink/genetlink.c:1065 > netlink_rcv_skb+0x3f8/0x750 net/netlink/af_netlink.c:2577 > genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076 > netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] > netlink_unicast+0xf41/0x1270 net/netlink/af_netlink.c:1365 > netlink_sendmsg+0x127d/0x1430 net/netlink/af_netlink.c:1942 > sock_sendmsg_nosec net/socket.c:724 [inline] > sock_sendmsg net/socket.c:747 [inline] > ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501 > ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555 > __sys_sendmsg net/socket.c:2584 [inline] > __do_sys_sendmsg net/socket.c:2593 [inline] > __se_sys_sendmsg net/socket.c:2591 [inline] > __x64_sys_sendmsg+0x36b/0x540 net/socket.c:2591 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > Uninit was stored to memory at: > tun_set_link_ksettings+0x37/0x60 drivers/net/tun.c:3553 > ethtool_set_link_ksettings+0x600/0x690 net/ethtool/ioctl.c:609 > __dev_ethtool net/ethtool/ioctl.c:3024 [inline] > dev_ethtool+0x1db9/0x2a70 net/ethtool/ioctl.c:3078 > dev_ioctl+0xb07/0x1270 net/core/dev_ioctl.c:524 > sock_do_ioctl+0x295/0x540 net/socket.c:1213 > sock_ioctl+0x729/0xd90 net/socket.c:1316 > vfs_ioctl fs/ioctl.c:51 [inline] > __do_sys_ioctl fs/ioctl.c:870 [inline] > __se_sys_ioctl+0x222/0x400 fs/ioctl.c:856 > __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:856 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > Local variable link_ksettings created at: > ethtool_set_link_ksettings+0x54/0x690 net/ethtool/ioctl.c:577 > __dev_ethtool net/ethtool/ioctl.c:3024 [inline] > dev_ethtool+0x1db9/0x2a70 net/ethtool/ioctl.c:3078 > > Fixes: 012ce4dd3102 ("ethtool: Extend link modes settings uAPI with lanes") > Reported-and-tested-by: syzbot+ef6edd9f1baaa54d6235@syzkaller.appspotmail.com > Link: https://lore.kernel.org/netdev/0000000000004bb41105fa70f361@google.com/ > Reviewed-by: Danielle Ratson <danieller@nvidia.com> > Signed-off-by: Ido Schimmel <idosch@nvidia.com> > --- > net/ethtool/ioctl.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > Thanks, Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Hello: This patch was applied to netdev/net.git (main) by David S. Miller <davem@davemloft.net>: On Tue, 2 May 2023 15:20:50 +0300 you wrote: > It is not possible to set the number of lanes when setting link modes > using the legacy IOCTL ethtool interface. Since 'struct > ethtool_link_ksettings' is not initialized in this path, drivers receive > an uninitialized number of lanes in 'struct > ethtool_link_ksettings::lanes'. > > When this information is later queried from drivers, it results in the > ethtool code making decisions based on uninitialized memory, leading to > the following KMSAN splat [1]. In practice, this most likely only > happens with the tun driver that simply returns whatever it got in the > set operation. > > [...] Here is the summary with links: - [net] ethtool: Fix uninitialized number of lanes https://git.kernel.org/netdev/net/c/9ad685dbfe7e You are awesome, thank you!
diff --git a/net/ethtool/ioctl.c b/net/ethtool/ioctl.c index 59adc4e6e9ee..6bb778e10461 100644 --- a/net/ethtool/ioctl.c +++ b/net/ethtool/ioctl.c @@ -574,8 +574,8 @@ static int ethtool_get_link_ksettings(struct net_device *dev, static int ethtool_set_link_ksettings(struct net_device *dev, void __user *useraddr) { + struct ethtool_link_ksettings link_ksettings = {}; int err; - struct ethtool_link_ksettings link_ksettings; ASSERT_RTNL();
It is not possible to set the number of lanes when setting link modes using the legacy IOCTL ethtool interface. Since 'struct ethtool_link_ksettings' is not initialized in this path, drivers receive an uninitialized number of lanes in 'struct ethtool_link_ksettings::lanes'. When this information is later queried from drivers, it results in the ethtool code making decisions based on uninitialized memory, leading to the following KMSAN splat [1]. In practice, this most likely only happens with the tun driver that simply returns whatever it got in the set operation. As far as I can tell, this uninitialized memory is not leaked to user space thanks to the 'ethtool_ops->cap_link_lanes_supported' check in linkmodes_prepare_data(). Fix by initializing the structure in the IOCTL path. Did not find any more call sites that pass an uninitialized structure when calling 'ethtool_ops::set_link_ksettings()'. [1] BUG: KMSAN: uninit-value in ethnl_update_linkmodes net/ethtool/linkmodes.c:273 [inline] BUG: KMSAN: uninit-value in ethnl_set_linkmodes+0x190b/0x19d0 net/ethtool/linkmodes.c:333 ethnl_update_linkmodes net/ethtool/linkmodes.c:273 [inline] ethnl_set_linkmodes+0x190b/0x19d0 net/ethtool/linkmodes.c:333 ethnl_default_set_doit+0x88d/0xde0 net/ethtool/netlink.c:640 genl_family_rcv_msg_doit net/netlink/genetlink.c:968 [inline] genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline] genl_rcv_msg+0x141a/0x14c0 net/netlink/genetlink.c:1065 netlink_rcv_skb+0x3f8/0x750 net/netlink/af_netlink.c:2577 genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0xf41/0x1270 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x127d/0x1430 net/netlink/af_netlink.c:1942 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555 __sys_sendmsg net/socket.c:2584 [inline] __do_sys_sendmsg net/socket.c:2593 [inline] __se_sys_sendmsg net/socket.c:2591 [inline] __x64_sys_sendmsg+0x36b/0x540 net/socket.c:2591 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Uninit was stored to memory at: tun_get_link_ksettings+0x37/0x60 drivers/net/tun.c:3544 __ethtool_get_link_ksettings+0x17b/0x260 net/ethtool/ioctl.c:441 ethnl_set_linkmodes+0xee/0x19d0 net/ethtool/linkmodes.c:327 ethnl_default_set_doit+0x88d/0xde0 net/ethtool/netlink.c:640 genl_family_rcv_msg_doit net/netlink/genetlink.c:968 [inline] genl_family_rcv_msg net/netlink/genetlink.c:1048 [inline] genl_rcv_msg+0x141a/0x14c0 net/netlink/genetlink.c:1065 netlink_rcv_skb+0x3f8/0x750 net/netlink/af_netlink.c:2577 genl_rcv+0x40/0x60 net/netlink/genetlink.c:1076 netlink_unicast_kernel net/netlink/af_netlink.c:1339 [inline] netlink_unicast+0xf41/0x1270 net/netlink/af_netlink.c:1365 netlink_sendmsg+0x127d/0x1430 net/netlink/af_netlink.c:1942 sock_sendmsg_nosec net/socket.c:724 [inline] sock_sendmsg net/socket.c:747 [inline] ____sys_sendmsg+0xa24/0xe40 net/socket.c:2501 ___sys_sendmsg+0x2a1/0x3f0 net/socket.c:2555 __sys_sendmsg net/socket.c:2584 [inline] __do_sys_sendmsg net/socket.c:2593 [inline] __se_sys_sendmsg net/socket.c:2591 [inline] __x64_sys_sendmsg+0x36b/0x540 net/socket.c:2591 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Uninit was stored to memory at: tun_set_link_ksettings+0x37/0x60 drivers/net/tun.c:3553 ethtool_set_link_ksettings+0x600/0x690 net/ethtool/ioctl.c:609 __dev_ethtool net/ethtool/ioctl.c:3024 [inline] dev_ethtool+0x1db9/0x2a70 net/ethtool/ioctl.c:3078 dev_ioctl+0xb07/0x1270 net/core/dev_ioctl.c:524 sock_do_ioctl+0x295/0x540 net/socket.c:1213 sock_ioctl+0x729/0xd90 net/socket.c:1316 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl+0x222/0x400 fs/ioctl.c:856 __x64_sys_ioctl+0x96/0xe0 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Local variable link_ksettings created at: ethtool_set_link_ksettings+0x54/0x690 net/ethtool/ioctl.c:577 __dev_ethtool net/ethtool/ioctl.c:3024 [inline] dev_ethtool+0x1db9/0x2a70 net/ethtool/ioctl.c:3078 Fixes: 012ce4dd3102 ("ethtool: Extend link modes settings uAPI with lanes") Reported-and-tested-by: syzbot+ef6edd9f1baaa54d6235@syzkaller.appspotmail.com Link: https://lore.kernel.org/netdev/0000000000004bb41105fa70f361@google.com/ Reviewed-by: Danielle Ratson <danieller@nvidia.com> Signed-off-by: Ido Schimmel <idosch@nvidia.com> --- net/ethtool/ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)