firmware: check for file truncation on direct firmware loading

When direct firmware loading is used we iterate over a list
of possible firmware paths and concatenate the desired firmware
name with each path and look for the file there. Should the
passed firmware name be too long we end up truncating the
file we want to look for, the search however is still done.
Add a check for truncation instead of looking for a
truncated firmware filename.

Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ming Lei <ming.lei@canonical.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@kernel.org>
Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/base/firmware_class.c b/drivers/base/firmware_class.c
index 49139a1ee25e6963bd532e8ef2376ed3e5675a11..9ffa70762473d8a9dc569b6506d0cc9c47753447 100644 (file)
--- a/drivers/base/firmware_class.c
+++ b/drivers/base/firmware_class.c
@@ -320,7 +320,7 @@ fail:
 static int fw_get_filesystem_firmware(struct device *device,
                                       struct firmware_buf *buf)
 {
-       int i;
+       int i, len;
        int rc = -ENOENT;
        char *path;
 
@@ -335,7 +335,12 @@ static int fw_get_filesystem_firmware(struct device *device,
                if (!fw_path[i][0])
                        continue;
 
-               snprintf(path, PATH_MAX, "%s/%s", fw_path[i], buf->fw_id);
+               len = snprintf(path, PATH_MAX, "%s/%s",
+                              fw_path[i], buf->fw_id);
+               if (len >= PATH_MAX) {
+                       rc = -ENAMETOOLONG;
+                       break;
+               }
 
                file = filp_open(path, O_RDONLY, 0);
                if (IS_ERR(file))