Re: CVS commit: src/sys/fs/msdosfs

[Izumi Tsutsui <tsutsui%ceres.dti.ne.jp@localhost>]

christos@ wrote:

> On Jul 5,  3:37am, tsutsui%ceres.dti.ne.jp@localhost (Izumi Tsutsui) wrote:
> -- Subject: Re: CVS commit: src/sys/fs/msdosfs
> 
> | > Well, I am not sure if KASSERT() is the best solution here. But
> | > what else can we do? I agree that there should be at least a
> | > warning.
> | 
> | Check
> | (secsize != 0 && secsize <= MAXBSIZE && powerof2(secsize) && numsec > 0)
> | in getdisksize() and return ENXIO if it fails?
> | It looks callers of getdisksize() check a returned error value
> | so they will also fail properly (refusing mountfs etc.),
> | even without a diagnostic warning.
> 
> Perhaps print a diagnostic, return -1 with EINVAL so that we know which
> driver failed?

getdisksize() returns error from ioctl's directly.
(because it's a kernel function?)

How about this dumb patch?

---
Index: subr_disk_open.c
===================================================================
RCS file: /cvsroot/src/sys/kern/subr_disk_open.c,v
retrieving revision 1.8
diff -u -p -r1.8 subr_disk_open.c
--- subr_disk_open.c    27 Apr 2012 18:15:55 -0000      1.8
+++ subr_disk_open.c    6 Jul 2012 12:51:34 -0000
@@ -89,28 +89,42 @@ opendisk(struct device *dv)
 }
 
 int
-getdisksize(struct vnode *vp, uint64_t *numsecp, unsigned *secsizep)
+getdisksize(struct vnode *vp, uint64_t *numsecp, unsigned int *secsizep)
 {
        struct partinfo dpart;
        struct dkwedge_info dkw;
        struct disk *pdk;
+       unsigned int secsize;
+       uint64_t numsec;
        int error;
 
        error = VOP_IOCTL(vp, DIOCGPART, &dpart, FREAD, NOCRED);
        if (error == 0) {
-               *secsizep = dpart.disklab->d_secsize;
-               *numsecp  = dpart.part->p_size;
-               return 0;
+               secsize = dpart.disklab->d_secsize;
+               numsec  = dpart.part->p_size;
+       } else {
+               error = VOP_IOCTL(vp, DIOCGWEDGEINFO, &dkw, FREAD, NOCRED);
+               if (error == 0) {
+                       pdk = disk_find(dkw.dkw_parent);
+                       if (pdk != NULL) {
+                               secsize = DEV_BSIZE << pdk->dk_blkshift;
+                               numsec  = dkw.dkw_size;
+                       } else
+                               error = ENODEV;
+               }
        }
 
-       error = VOP_IOCTL(vp, DIOCGWEDGEINFO, &dkw, FREAD, NOCRED);
-       if (error == 0) {
-               pdk = disk_find(dkw.dkw_parent);
-               if (pdk != NULL) {
-                       *secsizep = DEV_BSIZE << pdk->dk_blkshift;
-                       *numsecp  = dkw.dkw_size;
-               } else
-                       error = ENODEV;
+       if (error == 0 &&
+           (secsize == 0 || secsize > MAXBSIZE || !powerof2(secsize) ||
+            numsec == 0)) {
+#ifdef DIAGNOSTIC
+               printf("%s: %s returns invalid disksize values"
+                   " (secsize = %u, numsec = %" PRIu64 ")\n",
+                   __func__,
+                   devsw_blk2name(major(vp->v_specnode->sn_rdev)),
+                   secsize, numsec);
+#endif
+               error = EINVAL;
        }
 
        return error;

---
Izumi Tsutsui