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afs: Fix afs_atcell_get_link() to check if ws_cell is unset first
Fix afs_atcell_get_link() to check if the workstation cell is unset before
doing the RCU pathwalk bit where we dereference that.
Fixes: 823869e1e6 ("afs: Fix afs_atcell_get_link() to handle RCU pathwalk")
Reported-by: syzbot+76a6f18e3af82e84f264@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/2481796.1742296819@warthog.procyon.org.uk
Tested-by: syzbot+76a6f18e3af82e84f264@syzkaller.appspotmail.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
This commit is contained in:
committed by
Christian Brauner
parent
4701f33a10
commit
0307d16f36
@@ -314,6 +314,9 @@ static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inod
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const char *name;
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bool dotted = vnode->fid.vnode == 3;
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if (!rcu_access_pointer(net->ws_cell))
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return ERR_PTR(-ENOENT);
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if (!dentry) {
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/* We're in RCU-pathwalk. */
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cell = rcu_dereference(net->ws_cell);
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@@ -325,9 +328,6 @@ static const char *afs_atcell_get_link(struct dentry *dentry, struct inode *inod
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return name;
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}
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if (!rcu_access_pointer(net->ws_cell))
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return ERR_PTR(-ENOENT);
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down_read(&net->cells_lock);
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cell = rcu_dereference_protected(net->ws_cell, lockdep_is_held(&net->cells_lock));
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