Commit 4882a27c authored Jan 09, 2019 by Marc Dionne Committed by David Howells Jan 17, 2019

afs: Don't set vnode->cb_s_break in afs_validate()



A cb_interest record is not necessarily attached to the vnode on entry to
afs_validate(), which can cause an oops when we try to bring the vnode's
cb_s_break up to date in the default case (ie. no current callback promise
and the vnode has not been deleted).

Fix this by simply removing the line, as vnode->cb_s_break will be set when
needed by afs_register_server_cb_interest() when we next get a callback
promise from RPC call.

The oops looks something like:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
    ...
    RIP: 0010:afs_validate+0x66/0x250 [kafs]
    ...
    Call Trace:
     afs_d_revalidate+0x8d/0x340 [kafs]
     ? __d_lookup+0x61/0x150
     lookup_dcache+0x44/0x70
     ? lookup_dcache+0x44/0x70
     __lookup_hash+0x24/0xa0
     do_unlinkat+0x11d/0x2c0
     __x64_sys_unlink+0x23/0x30
     do_syscall_64+0x4d/0xf0
     entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: ae3b7361 ("afs: Fix validation/callback interaction")
Signed-off-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>

parent 5edc22cc

fs/afs/inode.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -414,7 +414,6 @@ int afs_validate(struct afs_vnode vnode, struct key key)
		} else if (test_bit(AFS_VNODE_DELETED, &vnode->flags)) {
		valid = true;
		} else {
		vnode->cb_s_break = vnode->cb_interest->server->cb_s_break;
		vnode->cb_v_break = vnode->volume->cb_v_break;
		valid = false;
		}

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