write$char_usb(r2, &(0x7f0000000040)="e2", 0x2778)
syz_open_dev$evdev(&(0x7f0000000100), 0x64a3, 0x31b003) (async)
syz_open_dev$evdev(&(0x7f0000000100), 0x64a3, 0x31b003)
panic: replaceArg: group fields don't match: 1/0

goroutine 24 [running]:
github.com/google/syzkaller/prog.replaceArg({0xe56770?, 0xc000666fa0?}, {0xe56770?, 0xc0006673c0?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/prog.go:377 +0x425
github.com/google/syzkaller/prog.replaceArg({0xe56770?, 0xc000666f80?}, {0xe56770?, 0xc0006673a0?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/prog.go:382 +0x345
github.com/google/syzkaller/prog.replaceArg({0xe56770?, 0xc000666f60?}, {0xe56770?, 0xc000667380?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/prog.go:382 +0x345
github.com/google/syzkaller/prog.replaceArg({0xe56770?, 0xc000666f40?}, {0xe56770?, 0xc000667360?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/prog.go:382 +0x345
github.com/google/syzkaller/prog.replaceArg({0xe56770?, 0xc000666f20?}, {0xe56770?, 0xc000667340?})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/prog.go:382 +0x345
github.com/google/syzkaller/prog.(*StructType).mutate(0x16d44a0, 0xc000667060, 0xc0018a2000, {0xe56770, 0xc000666f00?}, {0xc0012e1ef8, {0x1db72e0, 0x4, 0x4}, 0xc0012c8840, ...})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:490 +0x185
github.com/google/syzkaller/prog.(*Target).mutateArg(0x0?, 0xc0004453a0?, 0xc000779dc8?, {0xe56770, 0xc000666f00}, {0xc0012e1ef8, {0x1db72e0, 0x4, 0x4}, 0xc0012c8840, ...}, ...)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:245 +0xe2
github.com/google/syzkaller/prog.(*mutator).mutateArg(0xc000779e48)
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:196 +0x245
github.com/google/syzkaller/prog.(*Prog).Mutate(0xc0019a58c0, {0xe52aa8?, 0xc001280030}, 0x1e, 0xc001326300, 0xc000543140, {0xc000e6e000, 0x40f, 0x500})
	/syzkaller/gopath/src/github.com/google/syzkaller/prog/mutation.go:51 +0x2ba
main.(*Proc).loop(0xc00135e540)
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/proc.go:95 +0x365
created by main.main in goroutine 1
	/syzkaller/gopath/src/github.com/google/syzkaller/syz-fuzzer/fuzzer.go:336 +0x1665
[