5.4-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet edumazet@google.com
commit cbfbfe3aee718dc4c3c837f5d2463170ee59d78c upstream.
After commit 956db0a13b47 ("net: warn about attempts to register negative ifindex") syzbot is able to trigger the following splat.
Negative ifindex are not supported.
WARNING: CPU: 1 PID: 6003 at net/core/dev.c:9596 dev_index_reserve+0x104/0x210 Modules linked in: CPU: 1 PID: 6003 Comm: syz-executor926 Not tainted 6.6.0-rc4-syzkaller-g19af4a4ed414 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : dev_index_reserve+0x104/0x210 lr : dev_index_reserve+0x100/0x210 sp : ffff800096a878e0 x29: ffff800096a87930 x28: ffff0000d04380d0 x27: ffff0000d04380f8 x26: ffff0000d04380f0 x25: 1ffff00012d50f20 x24: 1ffff00012d50f1c x23: dfff800000000000 x22: ffff8000929c21c0 x21: 00000000ffffffea x20: ffff0000d04380e0 x19: ffff800096a87900 x18: ffff800096a874c0 x17: ffff800084df5008 x16: ffff80008051f9c4 x15: 0000000000000001 x14: 1fffe0001a087198 x13: 0000000000000000 x12: 0000000000000000 x11: 0000000000000000 x10: 0000000000000000 x9 : 0000000000000000 x8 : ffff0000d41c9bc0 x7 : 0000000000000000 x6 : 0000000000000000 x5 : ffff800091763d88 x4 : 0000000000000000 x3 : ffff800084e04748 x2 : 0000000000000001 x1 : 00000000fead71c7 x0 : 0000000000000000 Call trace: dev_index_reserve+0x104/0x210 register_netdevice+0x598/0x1074 net/core/dev.c:10084 tun_set_iff+0x630/0xb0c drivers/net/tun.c:2850 __tun_chr_ioctl+0x788/0x2af8 drivers/net/tun.c:3118 tun_chr_ioctl+0x38/0x4c drivers/net/tun.c:3403 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl fs/ioctl.c:857 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:857 __invoke_syscall arch/arm64/kernel/syscall.c:37 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:51 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:136 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:155 el0_svc+0x58/0x16c arch/arm64/kernel/entry-common.c:678 el0t_64_sync_handler+0x84/0xfc arch/arm64/kernel/entry-common.c:696 el0t_64_sync+0x190/0x194 arch/arm64/kernel/entry.S:595 irq event stamp: 11348 hardirqs last enabled at (11347): [<ffff80008a716574>] __raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:151 [inline] hardirqs last enabled at (11347): [<ffff80008a716574>] _raw_spin_unlock_irqrestore+0x38/0x98 kernel/locking/spinlock.c:194 hardirqs last disabled at (11348): [<ffff80008a627820>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:436 softirqs last enabled at (11138): [<ffff8000887ca53c>] spin_unlock_bh include/linux/spinlock.h:396 [inline] softirqs last enabled at (11138): [<ffff8000887ca53c>] release_sock+0x15c/0x1b0 net/core/sock.c:3531 softirqs last disabled at (11136): [<ffff8000887ca41c>] spin_lock_bh include/linux/spinlock.h:356 [inline] softirqs last disabled at (11136): [<ffff8000887ca41c>] release_sock+0x3c/0x1b0 net/core/sock.c:3518
Fixes: fb7589a16216 ("tun: Add ability to create tun device with given index") Reported-by: syzbot syzkaller@googlegroups.com Signed-off-by: Eric Dumazet edumazet@google.com Reviewed-by: Willem de Bruijn willemb@google.com Acked-by: Jason Wang jasowang@redhat.com Link: https://lore.kernel.org/r/20231016180851.3560092-1-edumazet@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/net/tun.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
--- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -3134,10 +3134,11 @@ static long __tun_chr_ioctl(struct file struct net *net = sock_net(&tfile->sk); struct tun_struct *tun; void __user* argp = (void __user*)arg; - unsigned int ifindex, carrier; + unsigned int carrier; struct ifreq ifr; kuid_t owner; kgid_t group; + int ifindex; int sndbuf; int vnet_hdr_sz; int le; @@ -3194,7 +3195,9 @@ static long __tun_chr_ioctl(struct file ret = -EFAULT; if (copy_from_user(&ifindex, argp, sizeof(ifindex))) goto unlock; - + ret = -EINVAL; + if (ifindex < 0) + goto unlock; ret = 0; tfile->ifindex = ifindex; goto unlock;