init: reduce PARTUUID min length to 1 from 36

Reduce the minimum length for a root=PARTUUID= parameter to be considered
valid from 36 to 1.  EFI/GPT partition UUIDs are always exactly 36
characters long, hence the previous limit.  However, the next patch will
support DOS/MBR UUIDs too, which have a different, shorter, format.
Instead of validating any particular length, just ensure that at least
some non-empty value was given by the user.

Also, consider a missing UUID value to be a parsing error, in the same
vein as if /PARTNROFF exists and can't be parsed.  As such, make both
error cases print a message and disable rootwait.  Convert to pr_err while
we're at it.

Signed-off-by: Stephen Warren <swarren@nvidia.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

1 files changed, 22 insertions, 13 deletions

diff --git a/init/do_mounts.c b/init/do_mounts.c
index b28ec5819325..c950d7c93f98 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -119,27 +119,29 @@ static dev_t devt_from_partuuid(const char *uuid_str)
         struct gendisk *disk;
         struct hd_struct *part;
         int offset = 0;
-
-        if (strlen(uuid_str) < 36)
-                goto done;
+        bool clear_root_wait = false;
+        char *slash;
 
         cmp.uuid = uuid_str;
-        cmp.len = 36;
 
+        slash = strchr(uuid_str, '/');
         /* Check for optional partition number offset attributes. */
-        if (uuid_str[36]) {
+        if (slash) {
                 char c = 0;
                 /* Explicitly fail on poor PARTUUID syntax. */
-                if (sscanf(&uuid_str[36],
-                           "/PARTNROFF=%d%c", &offset, &c) != 1) {
-                        printk(KERN_ERR "VFS: PARTUUID= is invalid.\n"
-                         "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
-                        if (root_wait)
-                                printk(KERN_ERR
-                                     "Disabling rootwait; root= is invalid.\n");
-                        root_wait = 0;
+                if (sscanf(slash + 1,
+                           "PARTNROFF=%d%c", &offset, &c) != 1) {
+                        clear_root_wait = true;
                         goto done;
                 }
+                cmp.len = slash - uuid_str;
+        } else {
+                cmp.len = strlen(uuid_str);
+        }
+
+        if (!cmp.len) {
+                clear_root_wait = true;
+                goto done;
         }
 
         dev = class_find_device(&block_class, NULL, &cmp,
@@ -164,6 +166,13 @@ static dev_t devt_from_partuuid(const char *uuid_str)
 no_offset:
         put_device(dev);
 done:
+        if (clear_root_wait) {
+                pr_err("VFS: PARTUUID= is invalid.\n"
+                       "Expected PARTUUID=<valid-uuid-id>[/PARTNROFF=%%d]\n");
+                if (root_wait)
+                        pr_err("Disabling rootwait; root= is invalid.\n");
+                root_wait = 0;
+        }
         return res;
 }
 #endif