Message ID | 20180129161611.11275-2-kleber.souza@canonical.com |
---|---|
State | New |
Headers | show |
Series | Fix for CVE-2018-5344 | expand |
On 29.01.2018 17:16, Kleber Sacilotto de Souza wrote: > From: Linus Torvalds <torvalds@linux-foundation.org> > > CVE-2018-5344 > > 范龙飞 reports that KASAN can report a use-after-free in __lock_acquire. > The reason is due to insufficient serialization in lo_release(), which > will continue to use the loop device even after it has decremented the > lo_refcnt to zero. > > In the meantime, another process can come in, open the loop device > again as it is being shut down. Confusion ensues. > > Reported-by: 范龙飞 <long7573@126.com> > Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> > Signed-off-by: Jens Axboe <axboe@kernel.dk> > (backported from commit ae6650163c66a7eff1acd6eb8b0f752dcfa8eba5 upstream) > Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> > --- > drivers/block/loop.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/block/loop.c b/drivers/block/loop.c > index 2e229ac94bdb..abcb85688916 100644 > --- a/drivers/block/loop.c > +++ b/drivers/block/loop.c > @@ -1529,9 +1529,8 @@ out: > return err; > } > > -static void lo_release(struct gendisk *disk, fmode_t mode) > +static void __lo_release(struct loop_device *lo) > { > - struct loop_device *lo = disk->private_data; > int err; > > mutex_lock(&lo->lo_ctl_mutex); > @@ -1559,6 +1558,13 @@ out: > mutex_unlock(&lo->lo_ctl_mutex); > } > > +static void lo_release(struct gendisk *disk, fmode_t mode) > +{ > + mutex_lock(&loop_index_mutex); > + __lo_release(disk->private_data); > + mutex_unlock(&loop_index_mutex); > +} > + > static const struct block_device_operations lo_fops = { > .owner = THIS_MODULE, > .open = lo_open, >
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 2e229ac94bdb..abcb85688916 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1529,9 +1529,8 @@ out: return err; } -static void lo_release(struct gendisk *disk, fmode_t mode) +static void __lo_release(struct loop_device *lo) { - struct loop_device *lo = disk->private_data; int err; mutex_lock(&lo->lo_ctl_mutex); @@ -1559,6 +1558,13 @@ out: mutex_unlock(&lo->lo_ctl_mutex); } +static void lo_release(struct gendisk *disk, fmode_t mode) +{ + mutex_lock(&loop_index_mutex); + __lo_release(disk->private_data); + mutex_unlock(&loop_index_mutex); +} + static const struct block_device_operations lo_fops = { .owner = THIS_MODULE, .open = lo_open,