[PATCH 4.14 66/91] ARM: amba: Dont read past the end of sysfs "driver_override" buffer

From: Greg Kroah-Hartman
Date: Mon Apr 30 2018 - 16:01:02 EST

4.14-stable review patch. If anyone has any objections, please let me know.


From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

commit d2ffed5185df9d8d9ccd150e4340e3b6f96a8381 upstream.

When printing the driver_override parameter when it is 4095 and 4094
bytes long, the printing code would access invalid memory because we
need count + 1 bytes for printing.

Cfr. commits 4efe874aace57dba ("PCI: Don't read past the end of sysfs
"driver_override" buffer") and bf563b01c2895a4b ("driver core: platform:
Don't read past the end of "driver_override" buffer").

Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
Reviewed-by: Todd Kjos <tkjos@xxxxxxxxxx>
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/amba/bus.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/amba/bus.c
+++ b/drivers/amba/bus.c
@@ -84,7 +84,8 @@ static ssize_t driver_override_store(str
struct amba_device *dev = to_amba_device(_dev);
char *driver_override, *old, *cp;

- if (count > PATH_MAX)
+ /* We need to keep extra room for a newline */
+ if (count >= (PAGE_SIZE - 1))
return -EINVAL;

driver_override = kstrndup(buf, count, GFP_KERNEL);