powerpc/64: Fix strncpy() related build failures with GCC 8.1

GCC 8.1 warns about possible string truncation:

  arch/powerpc/kernel/nvram_64.c:1042:2: error: 'strncpy' specified
  bound 12 equals destination size [-Werror=stringop-truncation]
    strncpy(new_part->header.name, name, 12);

  arch/powerpc/platforms/ps3/repository.c:106:2: error: 'strncpy'
  output truncated before terminating nul copying 8 bytes from a
  string of the same length [-Werror=stringop-truncation]
    strncpy((char *)&n, text, 8);

Fix it by using memcpy(). To make that safe we need to ensure the
destination is pre-zeroed. Use kzalloc() in the nvram code and
initialise the u64 to zero in the ps3 code.

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
[mpe: Use kzalloc() in the nvram code, flesh out change log]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/powerpc/platforms/ps3/repository.c b/arch/powerpc/platforms/ps3/repository.c
index 50dbaf24b1ee..e49c887787c4 100644
--- a/arch/powerpc/platforms/ps3/repository.c
+++ b/arch/powerpc/platforms/ps3/repository.c
@@ -101,9 +101,9 @@ static u64 make_first_field(const char *text, u64 index)
 
 static u64 make_field(const char *text, u64 index)
 {
-	u64 n;
+	u64 n = 0;
 
-	strncpy((char *)&n, text, 8);
+	memcpy((char *)&n, text, strnlen(text, sizeof(n)));
 	return n + index;
 }