4.19-stable review patch. If anyone has any objections, please let me know.
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From: Christophe JAILLET christophe.jaillet@wanadoo.fr
[ Upstream commit 48cf49d31994ff97b33c4044e618560ec84d35fb ]
snprintf() does not return negative values on error.
To know if the buffer was too small, the returned value needs to be compared with the length of the passed buffer. If it is greater or equal, the output has been truncated, so add checks for the truncation to create_pnp_modalias() and create_of_modalias(). Also make them return -ENOMEM in that case, as they already do that elsewhere.
Moreover, the remaining size of the buffer used by snprintf() needs to be updated after the first write to avoid out-of-bounds access as already done correctly in create_pnp_modalias(), but not in create_of_modalias(), so change the latter accordingly.
Fixes: 8765c5ba1949 ("ACPI / scan: Rework modalias creation when "compatible" is present") Signed-off-by: Christophe JAILLET christophe.jaillet@wanadoo.fr [ rjw: Merge two patches into one, combine changelogs, add subject ] Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/device_sysfs.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c index f792b149a5745..146be9cdeca5a 100644 --- a/drivers/acpi/device_sysfs.c +++ b/drivers/acpi/device_sysfs.c @@ -164,8 +164,8 @@ static int create_pnp_modalias(struct acpi_device *acpi_dev, char *modalias, return 0;
len = snprintf(modalias, size, "acpi:"); - if (len <= 0) - return len; + if (len >= size) + return -ENOMEM;
size -= len;
@@ -218,8 +218,10 @@ static int create_of_modalias(struct acpi_device *acpi_dev, char *modalias, len = snprintf(modalias, size, "of:N%sT", (char *)buf.pointer); ACPI_FREE(buf.pointer);
- if (len <= 0) - return len; + if (len >= size) + return -ENOMEM; + + size -= len;
of_compatible = acpi_dev->data.of_compatible; if (of_compatible->type == ACPI_TYPE_PACKAGE) {