From: Raghavendra Rao Ananta <rananta@google.com>
To: David Matlack <dmatlack@google.com>,
Alex Williamson <alex@shazbot.org>,
Alex Williamson <alex.williamson@redhat.com>
Cc: Vipin Sharma <vipinsh@google.com>,
Josh Hilke <jrhilke@google.com>,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Raghavendra Rao Ananta <rananta@google.com>
Subject: [PATCH v3 2/8] vfio: selftests: Introduce snprintf_assert()
Date: Wed, 4 Feb 2026 01:00:51 +0000 [thread overview]
Message-ID: <20260204010057.1079647-3-rananta@google.com> (raw)
In-Reply-To: <20260204010057.1079647-1-rananta@google.com>
Introduce snprintf_assert() to protect the users of snprintf() to fail
if the requested operation was truncated due to buffer limits. VFIO
tests and libraries, including a new sysfs library that will be introduced
by an upcoming patch, rely quite heavily on snprintf()s to build PCI
sysfs paths. Having a protection against this will be helpful to prevent
false test failures.
Signed-off-by: Raghavendra Rao Ananta <rananta@google.com>
---
.../vfio/lib/include/libvfio/assert.h | 5 +++++
.../selftests/vfio/lib/vfio_pci_device.c | 8 +++----
.../selftests/vfio/vfio_dma_mapping_test.c | 6 +++---
.../selftests/vfio/vfio_pci_device_test.c | 21 ++++++++++---------
4 files changed, 23 insertions(+), 17 deletions(-)
diff --git a/tools/testing/selftests/vfio/lib/include/libvfio/assert.h b/tools/testing/selftests/vfio/lib/include/libvfio/assert.h
index f4ebd122d9b6..77b68c7129a6 100644
--- a/tools/testing/selftests/vfio/lib/include/libvfio/assert.h
+++ b/tools/testing/selftests/vfio/lib/include/libvfio/assert.h
@@ -51,4 +51,9 @@
VFIO_ASSERT_EQ(__ret, 0, "ioctl(%s, %s, %s) returned %d\n", #_fd, #_op, #_arg, __ret); \
} while (0)
+#define snprintf_assert(_s, _size, _fmt, ...) do { \
+ int __ret = snprintf(_s, _size, _fmt, ##__VA_ARGS__); \
+ VFIO_ASSERT_LT(__ret, _size); \
+} while (0)
+
#endif /* SELFTESTS_VFIO_LIB_INCLUDE_LIBVFIO_ASSERT_H */
diff --git a/tools/testing/selftests/vfio/lib/vfio_pci_device.c b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
index 13fdb4b0b10f..64a19481b734 100644
--- a/tools/testing/selftests/vfio/lib/vfio_pci_device.c
+++ b/tools/testing/selftests/vfio/lib/vfio_pci_device.c
@@ -188,7 +188,7 @@ static unsigned int vfio_pci_get_group_from_dev(const char *bdf)
unsigned int group;
int ret;
- snprintf(sysfs_path, PATH_MAX, "%s/%s/iommu_group", PCI_SYSFS_PATH, bdf);
+ snprintf_assert(sysfs_path, PATH_MAX, "%s/%s/iommu_group", PCI_SYSFS_PATH, bdf);
ret = readlink(sysfs_path, dev_iommu_group_path, sizeof(dev_iommu_group_path));
VFIO_ASSERT_NE(ret, -1, "Failed to get the IOMMU group for device: %s\n", bdf);
@@ -208,7 +208,7 @@ static void vfio_pci_group_setup(struct vfio_pci_device *device, const char *bdf
int group;
group = vfio_pci_get_group_from_dev(bdf);
- snprintf(group_path, sizeof(group_path), "/dev/vfio/%d", group);
+ snprintf_assert(group_path, sizeof(group_path), "/dev/vfio/%d", group);
device->group_fd = open(group_path, O_RDWR);
VFIO_ASSERT_GE(device->group_fd, 0, "open(%s) failed\n", group_path);
@@ -279,7 +279,7 @@ const char *vfio_pci_get_cdev_path(const char *bdf)
cdev_path = calloc(PATH_MAX, 1);
VFIO_ASSERT_NOT_NULL(cdev_path);
- snprintf(dir_path, sizeof(dir_path), "/sys/bus/pci/devices/%s/vfio-dev/", bdf);
+ snprintf_assert(dir_path, sizeof(dir_path), "/sys/bus/pci/devices/%s/vfio-dev/", bdf);
dir = opendir(dir_path);
VFIO_ASSERT_NOT_NULL(dir, "Failed to open directory %s\n", dir_path);
@@ -289,7 +289,7 @@ const char *vfio_pci_get_cdev_path(const char *bdf)
if (strncmp("vfio", entry->d_name, 4))
continue;
- snprintf(cdev_path, PATH_MAX, "/dev/vfio/devices/%s", entry->d_name);
+ snprintf_assert(cdev_path, PATH_MAX, "/dev/vfio/devices/%s", entry->d_name);
break;
}
diff --git a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
index 5397822c3dd4..3a0bea5e2648 100644
--- a/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
+++ b/tools/testing/selftests/vfio/vfio_dma_mapping_test.c
@@ -45,9 +45,9 @@ static int intel_iommu_mapping_get(const char *bdf, u64 iova,
FILE *file;
char *rest;
- snprintf(iommu_mapping_path, sizeof(iommu_mapping_path),
- "/sys/kernel/debug/iommu/intel/%s/domain_translation_struct",
- bdf);
+ snprintf_assert(iommu_mapping_path, sizeof(iommu_mapping_path),
+ "/sys/kernel/debug/iommu/intel/%s/domain_translation_struct",
+ bdf);
printf("Searching for IOVA 0x%lx in %s\n", iova, iommu_mapping_path);
diff --git a/tools/testing/selftests/vfio/vfio_pci_device_test.c b/tools/testing/selftests/vfio/vfio_pci_device_test.c
index ecbb669b3765..723b56b485f6 100644
--- a/tools/testing/selftests/vfio/vfio_pci_device_test.c
+++ b/tools/testing/selftests/vfio/vfio_pci_device_test.c
@@ -39,16 +39,17 @@ FIXTURE_TEARDOWN(vfio_pci_device_test)
iommu_cleanup(self->iommu);
}
-#define read_pci_id_from_sysfs(_file) ({ \
- char __sysfs_path[PATH_MAX]; \
- char __buf[32]; \
- int __fd; \
- \
- snprintf(__sysfs_path, PATH_MAX, "/sys/bus/pci/devices/%s/%s", device_bdf, _file); \
- ASSERT_GT((__fd = open(__sysfs_path, O_RDONLY)), 0); \
- ASSERT_GT(read(__fd, __buf, ARRAY_SIZE(__buf)), 0); \
- ASSERT_EQ(0, close(__fd)); \
- (u16)strtoul(__buf, NULL, 0); \
+#define read_pci_id_from_sysfs(_file) ({ \
+ char __sysfs_path[PATH_MAX]; \
+ char __buf[32]; \
+ int __fd; \
+ \
+ snprintf_assert(__sysfs_path, PATH_MAX, "/sys/bus/pci/devices/%s/%s", \
+ device_bdf, _file); \
+ ASSERT_GT((__fd = open(__sysfs_path, O_RDONLY)), 0); \
+ ASSERT_GT(read(__fd, __buf, ARRAY_SIZE(__buf)), 0); \
+ ASSERT_EQ(0, close(__fd)); \
+ (u16)strtoul(__buf, NULL, 0); \
})
TEST_F(vfio_pci_device_test, config_space_read_write)
--
2.53.0.rc2.204.g2597b5adb4-goog
next prev parent reply other threads:[~2026-02-04 1:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-04 1:00 [PATCH v3 0/8] vfio: selftest: Add SR-IOV UAPI test Raghavendra Rao Ananta
2026-02-04 1:00 ` [PATCH v3 1/8] vfio: selftests: Add -Wall and -Werror to the Makefile Raghavendra Rao Ananta
2026-02-04 1:00 ` Raghavendra Rao Ananta [this message]
2026-02-04 1:00 ` [PATCH v3 3/8] vfio: selftests: Introduce a sysfs lib Raghavendra Rao Ananta
2026-02-06 20:48 ` Alex Williamson
2026-02-24 18:27 ` Raghavendra Rao Ananta
2026-02-04 1:00 ` [PATCH v3 4/8] vfio: selftests: Extend container/iommufd setup for passing vf_token Raghavendra Rao Ananta
2026-02-04 1:00 ` [PATCH v3 5/8] vfio: selftests: Expose more vfio_pci_device functions Raghavendra Rao Ananta
2026-02-04 1:00 ` [PATCH v3 6/8] vfio: selftests: Add helper to set/override a vf_token Raghavendra Rao Ananta
2026-02-04 1:00 ` [PATCH v3 7/8] vfio: selftests: Add helpers to alloc/free vfio_pci_device Raghavendra Rao Ananta
2026-02-04 1:00 ` [PATCH v3 8/8] vfio: selftests: Add tests to validate SR-IOV UAPI Raghavendra Rao Ananta
2026-02-05 0:44 ` [PATCH v3 0/8] vfio: selftest: Add SR-IOV UAPI test David Matlack
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