gcc 12.0.1 failed building libmultipath due to a format-overflow false
positive on 32-bit architectures. This isn't so surprising as
format-overflow=2 is very aggressive in the assumptions it makes about
the arguments. Here, it assumes that mpp->wwid could take up all the
space that a pointer could point to, even if I add code to this function
to explicitly null terminate mpp->wwid to fit in WWID_SIZE.
To avoid this and simplify the function, switch from using calloc() and
sprintf() to just using asprintf().
For reference, the gcc build error that this fixes is:
devmapper.c: In function 'dm_addmap.constprop.0':
devmapper.h:27:21: error: '%s' directive writing up to 2147483644 bytes into a region of size 2147483641 [-Werror=format-overflow=]
27 | #define UUID_PREFIX "mpath-"
| ^~~~~~~~
devmapper.c:484:53: note: format string is defined here
484 | sprintf(prefixed_uuid, UUID_PREFIX "%s", mpp->wwid);
| ^~
Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
---
libmultipath/devmapper.c | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/libmultipath/devmapper.c b/libmultipath/devmapper.c
index 36038150..2507f77f 100644
--- a/libmultipath/devmapper.c
+++ b/libmultipath/devmapper.c
@@ -473,14 +473,11 @@ dm_addmap (int task, const char *target, struct multipath *mpp,
dm_task_set_ro(dmt);
if (task == DM_DEVICE_CREATE) {
- prefixed_uuid = calloc(1, UUID_PREFIX_LEN +
- strlen(mpp->wwid) + 1);
- if (!prefixed_uuid) {
+ if (asprintf(&prefixed_uuid, UUID_PREFIX "%s", mpp->wwid) < 0) {
condlog(0, "cannot create prefixed uuid : %s",
strerror(errno));
goto addout;
}
- sprintf(prefixed_uuid, UUID_PREFIX "%s", mpp->wwid);
if (!dm_task_set_uuid(dmt, prefixed_uuid))
goto freeout;
dm_task_skip_lockfs(dmt);
--
2.17.2
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