of: module: add buffer overflow check in of_modalias()

commit cf7385cb26 upstream.

In of_modalias(), if the buffer happens to be too small even for the 1st
snprintf() call, the len parameter will become negative and str parameter
(if not NULL initially) will point beyond the buffer's end. Add the buffer
overflow check after the 1st snprintf() call and fix such check after the
strlen() call (accounting for the terminating NUL char).

Fixes: bc575064d6 ("of/device: use of_property_for_each_string to parse compatible strings")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/bbfc6be0-c687-62b6-d015-5141b93f313e@omp.ru
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: "Uwe Kleine-König" <ukleinek@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Sergey Shtylyov 2024-04-14 11:51:39 +03:00 committed by Greg Kroah-Hartman
parent cc826a9e1e
commit c7f24b7d94

View File

@ -257,14 +257,15 @@ static ssize_t of_device_get_modalias(struct device *dev, char *str, ssize_t len
csize = snprintf(str, len, "of:N%pOFn%c%s", dev->of_node, 'T',
of_node_get_device_type(dev->of_node));
tsize = csize;
if (csize >= len)
csize = len > 0 ? len - 1 : 0;
len -= csize;
if (str)
str += csize;
str += csize;
of_property_for_each_string(dev->of_node, "compatible", p, compat) {
csize = strlen(compat) + 1;
tsize += csize;
if (csize > len)
if (csize >= len)
continue;
csize = snprintf(str, len, "C%s", compat);