[PATCH 1/2] Replace snprintf with strncpy at some places to avoid truncation

[PATCH 1/2] Replace snprintf with strncpy at some places to avoid truncation

[Xiao Ni]

In gcc7 there are some building errors like:
directive output may be truncated writing up to 31 bytes into a region of size 24
snprintf(str, MPB_SIG_LEN, %s, mpb->sig);

It just need to copy one string to target. So use strncpy to replace it.

For this line code: snprintf(str, MPB_SIG_LEN, %s, mpb->sig);
Because mpb->sig has the content of version after magic, so
it's better to use strncpy to replace snprintf too.

Signed-off-by: Xiao Ni <xni@redhat.com>
---
 super-intel.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/super-intel.c b/super-intel.c
index d5e9517..343f20d 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -1811,7 +1811,8 @@ static void examine_super_imsm(struct supertype *st, char *homehost)
 	__u32 reserved = imsm_reserved_sectors(super, super->disks);
 	struct dl *dl;
 
-	snprintf(str, MPB_SIG_LEN, "%s", mpb->sig);
+	strncpy(str, (char *)mpb->sig, MPB_SIG_LEN);
+	str[MPB_SIG_LEN-1] = '\0';
 	printf("          Magic : %s\n", str);
 	snprintf(str, strlen(MPB_VERSION_RAID0), "%s", get_imsm_version(mpb));
 	printf("        Version : %s\n", get_imsm_version(mpb));
@@ -7142,14 +7143,16 @@ static int update_subarray_imsm(struct supertype *st, char *subarray,
 
 			u->type = update_rename_array;
 			u->dev_idx = vol;
-			snprintf((char *) u->name, MAX_RAID_SERIAL_LEN, "%s", name);
+			strncpy((char *) u->name, name, MAX_RAID_SERIAL_LEN);
+			u->name[MAX_RAID_SERIAL_LEN-1] = '\0';
 			append_metadata_update(st, u, sizeof(*u));
 		} else {
 			struct imsm_dev *dev;
 			int i;
 
 			dev = get_imsm_dev(super, vol);
-			snprintf((char *) dev->volume, MAX_RAID_SERIAL_LEN, "%s", name);
+			strncpy((char *) dev->volume, name, MAX_RAID_SERIAL_LEN);
+			dev->volume[MAX_RAID_SERIAL_LEN-1] = '\0';
 			for (i = 0; i < mpb->num_raid_devs; i++) {
 				dev = get_imsm_dev(super, i);
 				handle_missing(super, dev);
-- 
2.7.4

[PATCH 2/2] mdadm: Forced type conversion to avoid truncation

[Xiao Ni]

Gcc reports it needs 19 bytes to right to disk->serial. Because the type of argument i
is int. But the meaning of i is failed disk number. So it doesn't need to use 19 bytes.
Just add a type conversion to avoid this building error

Signed-off-by: Xiao Ni <xni@redhat.com>
---
 super-intel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/super-intel.c b/super-intel.c
index 343f20d..e1618f1 100644
--- a/super-intel.c
+++ b/super-intel.c
@@ -5228,7 +5228,7 @@ static int init_super_imsm_volume(struct supertype *st, mdu_array_info_t *info,
 			disk->status = CONFIGURED_DISK | FAILED_DISK;
 			disk->scsi_id = __cpu_to_le32(~(__u32)0);
 			snprintf((char *) disk->serial, MAX_RAID_SERIAL_LEN,
-				 "missing:%d", i);
+				 "missing:%d", (__u8)i);
 		}
 		find_missing(super);
 	} else {
-- 
2.7.4

Re: [PATCH 2/2] mdadm: Forced type conversion to avoid truncation

[jes.sorensen]

Xiao Ni <xni@redhat.com> writes:
> Gcc reports it needs 19 bytes to right to disk->serial. Because the type of argument i
> is int. But the meaning of i is failed disk number. So it doesn't need to use 19 bytes.
> Just add a type conversion to avoid this building error
>
> Signed-off-by: Xiao Ni <xni@redhat.com>
> ---
>  super-intel.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Applied!

I reformatted the commit message to keep it within 80 characters/line,
but no change of content.

Cheers,
Jes

Re: [PATCH 1/2] Replace snprintf with strncpy at some places to avoid truncation

[jes.sorensen]

Xiao Ni <xni@redhat.com> writes:
> In gcc7 there are some building errors like:
> directive output may be truncated writing up to 31 bytes into a region of size 24
> snprintf(str, MPB_SIG_LEN, %s, mpb->sig);
>
> It just need to copy one string to target. So use strncpy to replace it.
>
> For this line code: snprintf(str, MPB_SIG_LEN, %s, mpb->sig);
> Because mpb->sig has the content of version after magic, so
> it's better to use strncpy to replace snprintf too.
>
> Signed-off-by: Xiao Ni <xni@redhat.com>
> ---
>  super-intel.c | 9 ++++++---
>  1 file changed, 6 insertions(+), 3 deletions(-)

Applied!

Thanks,
Jes