From 733e62786bdf1b2b9dbb09ba2246313306503414 Mon Sep 17 00:00:00 2001 From: Sergey Shtylyov Date: Sun, 14 Apr 2024 11:51:39 +0300 Subject: [PATCH] of: module: add buffer overflow check in of_modalias() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit cf7385cb26ac4f0ee6c7385960525ad534323252 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: bc575064d688 ("of/device: use of_property_for_each_string to parse compatible strings") Signed-off-by: Sergey Shtylyov Link: https://lore.kernel.org/r/bbfc6be0-c687-62b6-d015-5141b93f313e@omp.ru Signed-off-by: Rob Herring Signed-off-by: "Uwe Kleine-König" Signed-off-by: Greg Kroah-Hartman --- drivers/of/device.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/of/device.c b/drivers/of/device.c index 3a547793135c3..93f08f18f6b3a 100644 --- a/drivers/of/device.c +++ b/drivers/of/device.c @@ -231,14 +231,15 @@ 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); -- 2.47.3