Date: Mon, 17 Nov 2003 11:06:06 +0100 From: Pawel Jakub Dawidek <nick@garage.freebsd.pl> To: freebsd-current@freebsd.org Subject: Panic after mount() fail. Message-ID: <20031117100606.GK85962@garage.freebsd.pl>
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Hello.
There is a problem with mount(2) failures. It can cause panics.
How-to-repeat.
# dd if=3D/dev/random of=3D/test.img bs=3D1m count=3D8
# mdconfig -a -t vnode -f /test.img -u 25
# mkdir -p /mnt/test
# mount /dev/md25 /mnt/test
(fail)
# mount /dev/md25 /mnt/test
(panic "Memory modified after free ...")
This is because on failure mutex is not destroyed.
Patch:
--- vfs_mount.c.orig Sun Nov 16 15:46:56 2003
+++ vfs_mount.c Sun Nov 16 15:21:48 2003
@@ -1061,6 +1061,7 @@ update:
vfs_unbusy(mp, td);
else {
mp->mnt_vfc->vfc_refcount--;
+ mtx_destroy(&mp->mnt_mtx);
vfs_unbusy(mp, td);
#ifdef MAC
mac_destroy_mount(mp);
@@ -1142,6 +1143,7 @@ update:
vp->v_iflag &=3D ~VI_MOUNT;
VI_UNLOCK(vp);
mp->mnt_vfc->vfc_refcount--;
+ mtx_destroy(&mp->mnt_mtx);
vfs_unbusy(mp, td);
#ifdef MAC
mac_destroy_mount(mp);
--=20
Pawel Jakub Dawidek pawel@dawidek.net
UNIX Systems Programmer/Administrator http://garage.freebsd.pl
Am I Evil? Yes, I Am! http://cerber.sourceforge.net
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