| Message ID | 20200916202457.400703-1-cascardo@canonical.com |
|---|---|
| State | New |
| Headers | show |
| Series | [SRU,oem-5.6] bcache: fix potential deadlock problem in btree_gc_coalesce | expand |
On 16.09.20 22:24, Thadeu Lima de Souza Cascardo wrote: > From: Zhiqiang Liu <liuzhiqiang26@huawei.com> > > coccicheck reports: > drivers/md//bcache/btree.c:1538:1-7: preceding lock on line 1417 > > In btree_gc_coalesce func, if the coalescing process fails, we will goto > to out_nocoalesce tag directly without releasing new_nodes[i]->write_lock. > Then, it will cause a deadlock when trying to acquire new_nodes[i]-> > write_lock for freeing new_nodes[i] before return. > > btree_gc_coalesce func details as follows: > if alloc new_nodes[i] fails: > goto out_nocoalesce; > // obtain new_nodes[i]->write_lock > mutex_lock(&new_nodes[i]->write_lock) > // main coalescing process > for (i = nodes - 1; i > 0; --i) > [snipped] > if coalescing process fails: > // Here, directly goto out_nocoalesce > // tag will cause a deadlock > goto out_nocoalesce; > [snipped] > // release new_nodes[i]->write_lock > mutex_unlock(&new_nodes[i]->write_lock) > // coalesing succ, return > return; > out_nocoalesce: > btree_node_free(new_nodes[i]) // free new_nodes[i] > // obtain new_nodes[i]->write_lock > mutex_lock(&new_nodes[i]->write_lock); > // set flag for reuse > clear_bit(BTREE_NODE_dirty, &ew_nodes[i]->flags); > // release new_nodes[i]->write_lock > mutex_unlock(&new_nodes[i]->write_lock); > > To fix the problem, we add a new tag 'out_unlock_nocoalesce' for > releasing new_nodes[i]->write_lock before out_nocoalesce tag. If > coalescing process fails, we will go to out_unlock_nocoalesce tag > for releasing new_nodes[i]->write_lock before free new_nodes[i] in > out_nocoalesce tag. > > (Coly Li helps to clean up commit log format.) > > Fixes: 2a285686c109816 ("bcache: btree locking rework") > Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> > Signed-off-by: Coly Li <colyli@suse.de> > Signed-off-by: Jens Axboe <axboe@kernel.dk> > (cherry picked from commit be23e837333a914df3f24bf0b32e87b0331ab8d1) > CVE-2020-12771 > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Acked-by: Stefan Bader <stefan.bader@canonical.com> > --- sob order > drivers/md/bcache/btree.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c > index fa872df4e770..cad8b0b97e33 100644 > --- a/drivers/md/bcache/btree.c > +++ b/drivers/md/bcache/btree.c > @@ -1447,7 +1447,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > if (__set_blocks(n1, n1->keys + n2->keys, > block_bytes(b->c)) > > btree_blocks(new_nodes[i])) > - goto out_nocoalesce; > + goto out_unlock_nocoalesce; > > keys = n2->keys; > /* Take the key of the node we're getting rid of */ > @@ -1476,7 +1476,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > > if (__bch_keylist_realloc(&keylist, > bkey_u64s(&new_nodes[i]->key))) > - goto out_nocoalesce; > + goto out_unlock_nocoalesce; > > bch_btree_node_write(new_nodes[i], &cl); > bch_keylist_add(&keylist, &new_nodes[i]->key); > @@ -1522,6 +1522,10 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > /* Invalidated our iterator */ > return -EINTR; > > +out_unlock_nocoalesce: > + for (i = 0; i < nodes; i++) > + mutex_unlock(&new_nodes[i]->write_lock); > + > out_nocoalesce: > closure_sync(&cl); > >
On 16/09/2020 21:24, Thadeu Lima de Souza Cascardo wrote: > From: Zhiqiang Liu <liuzhiqiang26@huawei.com> > > coccicheck reports: > drivers/md//bcache/btree.c:1538:1-7: preceding lock on line 1417 > > In btree_gc_coalesce func, if the coalescing process fails, we will goto > to out_nocoalesce tag directly without releasing new_nodes[i]->write_lock. > Then, it will cause a deadlock when trying to acquire new_nodes[i]-> > write_lock for freeing new_nodes[i] before return. > > btree_gc_coalesce func details as follows: > if alloc new_nodes[i] fails: > goto out_nocoalesce; > // obtain new_nodes[i]->write_lock > mutex_lock(&new_nodes[i]->write_lock) > // main coalescing process > for (i = nodes - 1; i > 0; --i) > [snipped] > if coalescing process fails: > // Here, directly goto out_nocoalesce > // tag will cause a deadlock > goto out_nocoalesce; > [snipped] > // release new_nodes[i]->write_lock > mutex_unlock(&new_nodes[i]->write_lock) > // coalesing succ, return > return; > out_nocoalesce: > btree_node_free(new_nodes[i]) // free new_nodes[i] > // obtain new_nodes[i]->write_lock > mutex_lock(&new_nodes[i]->write_lock); > // set flag for reuse > clear_bit(BTREE_NODE_dirty, &ew_nodes[i]->flags); > // release new_nodes[i]->write_lock > mutex_unlock(&new_nodes[i]->write_lock); > > To fix the problem, we add a new tag 'out_unlock_nocoalesce' for > releasing new_nodes[i]->write_lock before out_nocoalesce tag. If > coalescing process fails, we will go to out_unlock_nocoalesce tag > for releasing new_nodes[i]->write_lock before free new_nodes[i] in > out_nocoalesce tag. > > (Coly Li helps to clean up commit log format.) > > Fixes: 2a285686c109816 ("bcache: btree locking rework") > Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> > Signed-off-by: Coly Li <colyli@suse.de> > Signed-off-by: Jens Axboe <axboe@kernel.dk> > (cherry picked from commit be23e837333a914df3f24bf0b32e87b0331ab8d1) > CVE-2020-12771 > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> > --- > drivers/md/bcache/btree.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c > index fa872df4e770..cad8b0b97e33 100644 > --- a/drivers/md/bcache/btree.c > +++ b/drivers/md/bcache/btree.c > @@ -1447,7 +1447,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > if (__set_blocks(n1, n1->keys + n2->keys, > block_bytes(b->c)) > > btree_blocks(new_nodes[i])) > - goto out_nocoalesce; > + goto out_unlock_nocoalesce; > > keys = n2->keys; > /* Take the key of the node we're getting rid of */ > @@ -1476,7 +1476,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > > if (__bch_keylist_realloc(&keylist, > bkey_u64s(&new_nodes[i]->key))) > - goto out_nocoalesce; > + goto out_unlock_nocoalesce; > > bch_btree_node_write(new_nodes[i], &cl); > bch_keylist_add(&keylist, &new_nodes[i]->key); > @@ -1522,6 +1522,10 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > /* Invalidated our iterator */ > return -EINTR; > > +out_unlock_nocoalesce: > + for (i = 0; i < nodes; i++) > + mutex_unlock(&new_nodes[i]->write_lock); > + > out_nocoalesce: > closure_sync(&cl); > > Clean cherry pick. Looks good to me. Acked-by: Colin Ian King <colin.king@canonical.com>
On 16.9.2020 23.24, Thadeu Lima de Souza Cascardo wrote: > From: Zhiqiang Liu <liuzhiqiang26@huawei.com> > > coccicheck reports: > drivers/md//bcache/btree.c:1538:1-7: preceding lock on line 1417 > > In btree_gc_coalesce func, if the coalescing process fails, we will goto > to out_nocoalesce tag directly without releasing new_nodes[i]->write_lock. > Then, it will cause a deadlock when trying to acquire new_nodes[i]-> > write_lock for freeing new_nodes[i] before return. > > btree_gc_coalesce func details as follows: > if alloc new_nodes[i] fails: > goto out_nocoalesce; > // obtain new_nodes[i]->write_lock > mutex_lock(&new_nodes[i]->write_lock) > // main coalescing process > for (i = nodes - 1; i > 0; --i) > [snipped] > if coalescing process fails: > // Here, directly goto out_nocoalesce > // tag will cause a deadlock > goto out_nocoalesce; > [snipped] > // release new_nodes[i]->write_lock > mutex_unlock(&new_nodes[i]->write_lock) > // coalesing succ, return > return; > out_nocoalesce: > btree_node_free(new_nodes[i]) // free new_nodes[i] > // obtain new_nodes[i]->write_lock > mutex_lock(&new_nodes[i]->write_lock); > // set flag for reuse > clear_bit(BTREE_NODE_dirty, &ew_nodes[i]->flags); > // release new_nodes[i]->write_lock > mutex_unlock(&new_nodes[i]->write_lock); > > To fix the problem, we add a new tag 'out_unlock_nocoalesce' for > releasing new_nodes[i]->write_lock before out_nocoalesce tag. If > coalescing process fails, we will go to out_unlock_nocoalesce tag > for releasing new_nodes[i]->write_lock before free new_nodes[i] in > out_nocoalesce tag. > > (Coly Li helps to clean up commit log format.) > > Fixes: 2a285686c109816 ("bcache: btree locking rework") > Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> > Signed-off-by: Coly Li <colyli@suse.de> > Signed-off-by: Jens Axboe <axboe@kernel.dk> > (cherry picked from commit be23e837333a914df3f24bf0b32e87b0331ab8d1) > CVE-2020-12771 > Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> > --- > drivers/md/bcache/btree.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c > index fa872df4e770..cad8b0b97e33 100644 > --- a/drivers/md/bcache/btree.c > +++ b/drivers/md/bcache/btree.c > @@ -1447,7 +1447,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > if (__set_blocks(n1, n1->keys + n2->keys, > block_bytes(b->c)) > > btree_blocks(new_nodes[i])) > - goto out_nocoalesce; > + goto out_unlock_nocoalesce; > > keys = n2->keys; > /* Take the key of the node we're getting rid of */ > @@ -1476,7 +1476,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > > if (__bch_keylist_realloc(&keylist, > bkey_u64s(&new_nodes[i]->key))) > - goto out_nocoalesce; > + goto out_unlock_nocoalesce; > > bch_btree_node_write(new_nodes[i], &cl); > bch_keylist_add(&keylist, &new_nodes[i]->key); > @@ -1522,6 +1522,10 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, > /* Invalidated our iterator */ > return -EINTR; > > +out_unlock_nocoalesce: > + for (i = 0; i < nodes; i++) > + mutex_unlock(&new_nodes[i]->write_lock); > + > out_nocoalesce: > closure_sync(&cl); > > applied to oem-5.6, thanks
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c index fa872df4e770..cad8b0b97e33 100644 --- a/drivers/md/bcache/btree.c +++ b/drivers/md/bcache/btree.c @@ -1447,7 +1447,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, if (__set_blocks(n1, n1->keys + n2->keys, block_bytes(b->c)) > btree_blocks(new_nodes[i])) - goto out_nocoalesce; + goto out_unlock_nocoalesce; keys = n2->keys; /* Take the key of the node we're getting rid of */ @@ -1476,7 +1476,7 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, if (__bch_keylist_realloc(&keylist, bkey_u64s(&new_nodes[i]->key))) - goto out_nocoalesce; + goto out_unlock_nocoalesce; bch_btree_node_write(new_nodes[i], &cl); bch_keylist_add(&keylist, &new_nodes[i]->key); @@ -1522,6 +1522,10 @@ static int btree_gc_coalesce(struct btree *b, struct btree_op *op, /* Invalidated our iterator */ return -EINTR; +out_unlock_nocoalesce: + for (i = 0; i < nodes; i++) + mutex_unlock(&new_nodes[i]->write_lock); + out_nocoalesce: closure_sync(&cl);