[PATCH] mtd: sm_ftl: fix NULL pointer warning

From: Arnd Bergmann
Date: Tue Jan 07 2020 - 16:25:38 EST

With gcc -O3, we get a new warning:

In file included from arch/arm64/include/asm/processor.h:28,
from drivers/mtd/sm_ftl.c:8:
In function 'memset',
inlined from 'sm_read_sector.constprop' at drivers/mtd/sm_ftl.c:250:3:
include/linux/string.h:411:9: error: argument 1 null where non-null expected [-Werror=nonnull]
return __builtin_memset(p, c, size);

>From all I can tell, this cannot happen (the function is called
either with a NULL buffer or with a -1 block number but not both),
but adding a check makes it more robust and avoids the warning.

Fixes: mmtom ("init/Kconfig: enable -O3 for all arches")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
drivers/mtd/sm_ftl.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/sm_ftl.c b/drivers/mtd/sm_ftl.c
index 4744bf94ad9a..b9f272408c4d 100644
--- a/drivers/mtd/sm_ftl.c
+++ b/drivers/mtd/sm_ftl.c
@@ -247,7 +247,8 @@ static int sm_read_sector(struct sm_ftl *ftl,

/* FTL can contain -1 entries that are by default filled with bits */
if (block == -1) {
- memset(buffer, 0xFF, SM_SECTOR_SIZE);
+ if (buffer)
+ memset(buffer, 0xFF, SM_SECTOR_SIZE);
return 0;