4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 4882a27cec24319d10f95e978ecc80050e3e3e15 ]
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: ae3b7361dc0e ("afs: Fix validation/callback interaction") Signed-off-by: Marc Dionne marc.dionne@auristor.com Signed-off-by: David Howells dhowells@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/afs/inode.c | 1 - 1 file changed, 1 deletion(-)
diff --git a/fs/afs/inode.c b/fs/afs/inode.c index 6b17d36204142..211343831c304 100644 --- a/fs/afs/inode.c +++ b/fs/afs/inode.c @@ -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; }