diff --git a/sys/amd64/amd64/uio_machdep.c b/sys/amd64/amd64/uio_machdep.c
--- a/sys/amd64/amd64/uio_machdep.c
+++ b/sys/amd64/amd64/uio_machdep.c
@@ -71,10 +71,16 @@
 	    ("uiomove_fromphys: mode"));
 	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove_fromphys proc"));
+	KASSERT(uio->uio_resid >= 0,
+	    ("%s: uio %p resid underflow", __func__, uio));
+
 	save = td->td_pflags & TDP_DEADLKTREAT;
 	td->td_pflags |= TDP_DEADLKTREAT;
 	mapped = false;
 	while (n > 0 && uio->uio_resid) {
+		KASSERT(uio->uio_iovcnt > 0,
+		    ("%s: uio %p iovcnt underflow", __func__, uio));
+
 		iov = uio->uio_iov;
 		cnt = iov->iov_len;
 		if (cnt == 0) {
diff --git a/sys/arm/arm/uio_machdep.c b/sys/arm/arm/uio_machdep.c
--- a/sys/arm/arm/uio_machdep.c
+++ b/sys/arm/arm/uio_machdep.c
@@ -72,9 +72,15 @@
 	    ("uiomove_fromphys: mode"));
 	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove_fromphys proc"));
+	KASSERT(uio->uio_resid >= 0,
+	    ("%s: uio %p resid underflow", __func__, uio));
+
 	save = td->td_pflags & TDP_DEADLKTREAT;
 	td->td_pflags |= TDP_DEADLKTREAT;
 	while (n > 0 && uio->uio_resid) {
+		KASSERT(uio->uio_iovcnt > 0,
+		    ("%s: uio %p iovcnt underflow", __func__, uio));
+
 		iov = uio->uio_iov;
 		cnt = iov->iov_len;
 		if (cnt == 0) {
diff --git a/sys/arm64/arm64/uio_machdep.c b/sys/arm64/arm64/uio_machdep.c
--- a/sys/arm64/arm64/uio_machdep.c
+++ b/sys/arm64/arm64/uio_machdep.c
@@ -69,10 +69,16 @@
 	    ("uiomove_fromphys: mode"));
 	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove_fromphys proc"));
+	KASSERT(uio->uio_resid >= 0,
+	    ("%s: uio %p resid underflow", __func__, uio));
+
 	save = td->td_pflags & TDP_DEADLKTREAT;
 	td->td_pflags |= TDP_DEADLKTREAT;
 	mapped = false;
 	while (n > 0 && uio->uio_resid) {
+		KASSERT(uio->uio_iovcnt > 0,
+		    ("%s: uio %p iovcnt underflow", __func__, uio));
+
 		iov = uio->uio_iov;
 		cnt = iov->iov_len;
 		if (cnt == 0) {
diff --git a/sys/i386/i386/uio_machdep.c b/sys/i386/i386/uio_machdep.c
--- a/sys/i386/i386/uio_machdep.c
+++ b/sys/i386/i386/uio_machdep.c
@@ -71,9 +71,15 @@
 	    ("uiomove_fromphys: mode"));
 	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove_fromphys proc"));
+	KASSERT(uio->uio_resid >= 0,
+	    ("%s: uio %p resid underflow", __func__, uio));
+
 	save = td->td_pflags & TDP_DEADLKTREAT;
 	td->td_pflags |= TDP_DEADLKTREAT;
 	while (n > 0 && uio->uio_resid) {
+		KASSERT(uio->uio_iovcnt > 0,
+		    ("%s: uio %p iovcnt underflow", __func__, uio));
+
 		iov = uio->uio_iov;
 		cnt = iov->iov_len;
 		if (cnt == 0) {
diff --git a/sys/kern/subr_uio.c b/sys/kern/subr_uio.c
--- a/sys/kern/subr_uio.c
+++ b/sys/kern/subr_uio.c
@@ -216,6 +216,8 @@
 	    ("uiomove: mode"));
 	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove proc"));
+	KASSERT(uio->uio_resid >= 0,
+	    ("%s: uio %p resid underflow", __func__, uio));
 
 	if (uio->uio_segflg == UIO_USERSPACE) {
 		newflags = TDP_DEADLKTREAT;
@@ -234,6 +236,9 @@
 	}
 
 	while (n > 0 && uio->uio_resid) {
+		KASSERT(uio->uio_iovcnt > 0,
+		    ("%s: uio %p iovcnt underflow", __func__, uio));
+
 		iov = uio->uio_iov;
 		cnt = iov->iov_len;
 		if (cnt == 0) {
diff --git a/sys/powerpc/powerpc/uio_machdep.c b/sys/powerpc/powerpc/uio_machdep.c
--- a/sys/powerpc/powerpc/uio_machdep.c
+++ b/sys/powerpc/powerpc/uio_machdep.c
@@ -75,10 +75,15 @@
 	    ("uiomove_fromphys: mode"));
 	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove_fromphys proc"));
+	KASSERT(uio->uio_resid >= 0,
+	    ("%s: uio %p resid underflow", __func__, uio));
 
 	save = td->td_pflags & TDP_DEADLKTREAT;
 	td->td_pflags |= TDP_DEADLKTREAT;
 	while (n > 0 && uio->uio_resid) {
+		KASSERT(uio->uio_iovcnt > 0,
+		    ("%s: uio %p iovcnt underflow", __func__, uio));
+
 		iov = uio->uio_iov;
 		cnt = iov->iov_len;
 		if (cnt == 0) {
diff --git a/sys/riscv/riscv/uio_machdep.c b/sys/riscv/riscv/uio_machdep.c
--- a/sys/riscv/riscv/uio_machdep.c
+++ b/sys/riscv/riscv/uio_machdep.c
@@ -69,10 +69,16 @@
 	    ("uiomove_fromphys: mode"));
 	KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
 	    ("uiomove_fromphys proc"));
+	KASSERT(uio->uio_resid >= 0,
+	    ("%s: uio %p resid underflow", __func__, uio));
+
 	save = td->td_pflags & TDP_DEADLKTREAT;
 	td->td_pflags |= TDP_DEADLKTREAT;
 	mapped = false;
 	while (n > 0 && uio->uio_resid) {
+		KASSERT(uio->uio_iovcnt > 0,
+		    ("%s: uio %p iovcnt underflow", __func__, uio));
+
 		iov = uio->uio_iov;
 		cnt = iov->iov_len;
 		if (cnt == 0) {