lib: uuid: alignment error in gen_rand_uuid()

Packed structures like struct uuid are not aligned. GCC 9.1 therefore
throws an error when trying to compile gen_rand_uuid().

lib/uuid.c: In function ‘gen_rand_uuid’:
lib/uuid.c:244:2: error: converting a packed ‘struct uuid’ pointer
(alignment 1) to a ‘unsigned int’ pointer (alignment 4) may result in
an unaligned pointer value [-Werror=address-of-packed-member]
  244 |  unsigned int *ptr = (unsigned int *)&uuid;
      |  ^~~~~~~~

Generate the uuid in a properly aligned buffer.

The byte order of a random number should not matter. Do not call
cpu_to_be32() to change the byte order.

Reported-by: Ramon Fried <rfried.dev@gmail.com>
Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>

diff --git a/lib/uuid.c b/lib/uuid.c
index 7d7a2749b6410650362b6b0fa9c1b618872b893f..ca8be2cdca41b54dfc2e1aecd0224204385e633a 100644 (file)
--- a/lib/uuid.c
+++ b/lib/uuid.c
@@ -240,25 +240,25 @@ void uuid_bin_to_str(unsigned char *uuid_bin, char *uuid_str, int str_format)
 #if defined(CONFIG_RANDOM_UUID) || defined(CONFIG_CMD_UUID)
 void gen_rand_uuid(unsigned char *uuid_bin)
 {
-       struct uuid uuid;
-       unsigned int *ptr = (unsigned int *)&uuid;
+       u32 ptr[4];
+       struct uuid *uuid = (struct uuid *)ptr;
        int i;
 
        srand(get_ticks() + rand());
 
        /* Set all fields randomly */
-       for (i = 0; i < sizeof(struct uuid) / sizeof(*ptr); i++)
-               *(ptr + i) = cpu_to_be32(rand());
+       for (i = 0; i < 4; i++)
+               ptr[i] = rand();
 
-       clrsetbits_be16(&uuid.time_hi_and_version,
+       clrsetbits_be16(&uuid->time_hi_and_version,
                        UUID_VERSION_MASK,
                        UUID_VERSION << UUID_VERSION_SHIFT);
 
-       clrsetbits_8(&uuid.clock_seq_hi_and_reserved,
+       clrsetbits_8(&uuid->clock_seq_hi_and_reserved,
                     UUID_VARIANT_MASK,
                     UUID_VARIANT << UUID_VARIANT_SHIFT);
 
-       memcpy(uuid_bin, &uuid, sizeof(struct uuid));
+       memcpy(uuid_bin, uuid, 16);
 }
 
 /*