Detect too-small device: error rather than underflow/crash

[thirdparty/mdadm.git] / super1.c

diff --git a/super1.c b/super1.c
index e0d80be1e5dfa22e3358b5bd1274e85719f08938..76648835bf8ff668bd0283b02431ba1b76dc86c1 100644 (file)
--- a/super1.c
+++ b/super1.c
@@ -2753,6 +2753,7 @@ static int validate_geometry1(struct supertype *st, int level,
        unsigned long long ldsize, devsize;
        int bmspace;
        unsigned long long headroom;
+       unsigned long long overhead;
        int fd;
 
        if (level == LEVEL_CONTAINER) {
@@ -2785,10 +2786,6 @@ static int validate_geometry1(struct supertype *st, int level,
        close(fd);
 
        devsize = ldsize >> 9;
-       if (devsize < 24) {
-               *freesize = 0;
-               return 0;
-       }
 
        /* creating:  allow suitable space for bitmap or PPL */
        if (consistency_policy == CONSISTENCY_POLICY_PPL)
@@ -2829,15 +2826,27 @@ static int validate_geometry1(struct supertype *st, int level,
        case 0: /* metadata at end.  Round down and subtract space to reserve */
                devsize = (devsize & ~(4ULL*2-1));
                /* space for metadata, bblog, bitmap/ppl */
-               devsize -= 8*2 + 8 + bmspace;
+               overhead = 8*2 + 8 + bmspace;
+               if (devsize < overhead) /* detect underflow */
+                       goto dev_too_small_err;
+               devsize -= overhead;
                break;
        case 1:
        case 2:
+               if (devsize < data_offset) /* detect underflow */
+                       goto dev_too_small_err;
                devsize -= data_offset;
                break;
        }
        *freesize = devsize;
        return 1;
+
+/* Error condition, device cannot even hold the overhead. */
+dev_too_small_err:
+       fprintf(stderr, "device %s is too small (%lluK) for "
+                       "required metadata!\n", subdev, devsize>>1);
+       *freesize = 0;
+       return 0;
 }
 
 void *super1_make_v0(struct supertype *st, struct mdinfo *info, mdp_super_t *sb0)