From: Alex Williamson <alex.williamson@redhat.com>
Date: Wed, 22 Jan 2025 17:38:30 +0000 (-0700)
Subject: vfio/platform: check the bounds of read/write syscalls
X-Git-Tag: v5.15.178~15
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=92340e6c5122d823ad064984ef7513eba9204048;p=thirdparty%2Fkernel%2Fstable.git

vfio/platform: check the bounds of read/write syscalls

commit ce9ff21ea89d191e477a02ad7eabf4f996b80a69 upstream.

count and offset are passed from user space and not checked, only
offset is capped to 40 bits, which can be used to read/write out of
bounds of the device.

Fixes: 6e3f26456009 (“vfio/platform: read and write support for the device fd”)
Cc: stable@vger.kernel.org
Reported-by: Mostafa Saleh <smostafa@google.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Mostafa Saleh <smostafa@google.com>
Tested-by: Mostafa Saleh <smostafa@google.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/vfio/platform/vfio_platform_common.c b/drivers/vfio/platform/vfio_platform_common.c
index 701bd99a87198..5c5f944ca31e9 100644
--- a/drivers/vfio/platform/vfio_platform_common.c
+++ b/drivers/vfio/platform/vfio_platform_common.c
@@ -388,6 +388,11 @@ static ssize_t vfio_platform_read_mmio(struct vfio_platform_region *reg,
 {
 	unsigned int done = 0;
 
+	if (off >= reg->size)
+		return -EINVAL;
+
+	count = min_t(size_t, count, reg->size - off);
+
 	if (!reg->ioaddr) {
 		reg->ioaddr =
 			ioremap(reg->addr, reg->size);
@@ -466,6 +471,11 @@ static ssize_t vfio_platform_write_mmio(struct vfio_platform_region *reg,
 {
 	unsigned int done = 0;
 
+	if (off >= reg->size)
+		return -EINVAL;
+
+	count = min_t(size_t, count, reg->size - off);
+
 	if (!reg->ioaddr) {
 		reg->ioaddr =
 			ioremap(reg->addr, reg->size);