| Message ID | 20241022071316.778660-1-mtsai@redhat.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | dm cache: fix OOB and error handling in cache creation and resizing | expand |
ack On Tue, Oct 22, 2024 at 8:13 AM Ming-Hung Tsai <mtsai@redhat.com> wrote: > > dm-cache checks the dirty bits of the cache blocks to be dropped when > shrinking the fast device, but an index bug in bitset iteration causes > out-of-bounds access. > > Reproduce steps: > > 1. create a cache device of 1024 cache blocks (128 bytes dirty bitset) > > dmsetup create cmeta --table "0 8192 linear /dev/sdc 0" > dmsetup create cdata --table "0 131072 linear /dev/sdc 8192" > dmsetup create corig --table "0 524288 linear /dev/sdc 262144" > dd if=/dev/zero of=/dev/mapper/cmeta bs=4k count=1 oflag=direct > dmsetup create cache --table "0 524288 cache /dev/mapper/cmeta \ > /dev/mapper/cdata /dev/mapper/corig 128 2 metadata2 writethrough smq 0" > > 2. shrink the fast device to 512 cache blocks, triggering out-of-bounds > access to the dirty bitset (offset 0x80) > > dmsetup suspend cache > dmsetup reload cdata --table "0 65536 linear /dev/sdc 8192" > dmsetup resume cdata > dmsetup resume cache > > KASAN reports: > > BUG: KASAN: vmalloc-out-of-bounds in cache_preresume+0x269/0x7b0 > Read of size 8 at addr ffffc900000f3080 by task dmsetup/131 > > (...snip...) > The buggy address belongs to the virtual mapping at > [ffffc900000f3000, ffffc900000f5000) created by: > cache_ctr+0x176a/0x35f0 > > (...snip...) > Memory state around the buggy address: > ffffc900000f2f80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > ffffc900000f3000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > >ffffc900000f3080: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > ^ > ffffc900000f3100: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > ffffc900000f3180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 > > Fix by making the index post-incremented. > > Signed-off-by: Ming-Hung Tsai <mtsai@redhat.com> > Fixes: f494a9c6b1b6 ("dm cache: cache shrinking support") > --- > drivers/md/dm-cache-target.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c > index 68e9a1abd303..1fcd8c5c220e 100644 > --- a/drivers/md/dm-cache-target.c > +++ b/drivers/md/dm-cache-target.c > @@ -2912,13 +2912,13 @@ static bool can_resize(struct cache *cache, dm_cblock_t new_size) > * We can't drop a dirty block when shrinking the cache. > */ > while (from_cblock(new_size) < from_cblock(cache->cache_size)) { > - new_size = to_cblock(from_cblock(new_size) + 1); > if (is_dirty(cache, new_size)) { > DMERR("%s: unable to shrink cache; cache block %llu is dirty", > cache_device_name(cache), > (unsigned long long) from_cblock(new_size)); > return false; > } > + new_size = to_cblock(from_cblock(new_size) + 1); > } > > return true; > -- > 2.47.0 >
diff --git a/drivers/md/dm-cache-target.c b/drivers/md/dm-cache-target.c index 68e9a1abd303..1fcd8c5c220e 100644 --- a/drivers/md/dm-cache-target.c +++ b/drivers/md/dm-cache-target.c @@ -2912,13 +2912,13 @@ static bool can_resize(struct cache *cache, dm_cblock_t new_size) * We can't drop a dirty block when shrinking the cache. */ while (from_cblock(new_size) < from_cblock(cache->cache_size)) { - new_size = to_cblock(from_cblock(new_size) + 1); if (is_dirty(cache, new_size)) { DMERR("%s: unable to shrink cache; cache block %llu is dirty", cache_device_name(cache), (unsigned long long) from_cblock(new_size)); return false; } + new_size = to_cblock(from_cblock(new_size) + 1); } return true;