The ext2fs_check_mount_point() function can be called with mtpt being
NULL as for example from ext2fs_check_if_mounted(). However in the
is_swap_device condition we use the mtpt in strncpy without checking
whether it is non-null first.
This should not be a problem on linux since the previous attempt to open
the device exclusively would have prevented us from ever reaching the
problematic strncpy. However it's still a bug and can cause problems on
other systems, fix it by conditioning strncpy on mtpt not being null.
Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
---
lib/ext2fs/ismounted.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/lib/ext2fs/ismounted.c b/lib/ext2fs/ismounted.c
index c9e6a9d0..aee7d726 100644
--- a/lib/ext2fs/ismounted.c
+++ b/lib/ext2fs/ismounted.c
@@ -393,7 +393,8 @@ errcode_t ext2fs_check_mount_point(const char *device, int *mount_flags,
if (is_swap_device(device)) {
*mount_flags = EXT2_MF_MOUNTED | EXT2_MF_SWAP;
- strncpy(mtpt, "<swap>", mtlen);
+ if (mtpt)
+ strncpy(mtpt, "<swap>", mtlen);
} else {
#ifdef HAVE_SETMNTENT
retval = check_mntent(device, mount_flags, mtpt, mtlen);
--
2.31.1
