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From f8789858be5c1b13543040b74d978ea448461155 Mon Sep 17 00:00:00 2001
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From: David Howells <dhowells@redhat.com>
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Date: Tue, 15 Nov 2011 22:09:45 +0000
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Subject: [PATCH] KEYS: Fix a NULL pointer deref in the user-defined key type
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commit 9f35a33b8d06263a165efe3541d9aa0cdbd70b3b upstream.
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Fix a NULL pointer deref in the user-defined key type whereby updating a
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negative key into a fully instantiated key will cause an oops to occur
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when the code attempts to free the non-existent old payload.
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This results in an oops that looks something like the following:
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BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
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IP: [<ffffffff81085fa1>] __call_rcu+0x11/0x13e
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PGD 3391d067 PUD 3894a067 PMD 0
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Oops: 0002 [#1] SMP
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CPU 1
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Pid: 4354, comm: keyctl Not tainted 3.1.0-fsdevel+ #1140 /DG965RY
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RIP: 0010:[<ffffffff81085fa1>] [<ffffffff81085fa1>] __call_rcu+0x11/0x13e
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RSP: 0018:ffff88003d591df8 EFLAGS: 00010246
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RAX: 0000000000000000 RBX: 0000000000000000 RCX: 000000000000006e
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RDX: ffffffff8161d0c0 RSI: 0000000000000000 RDI: 0000000000000000
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RBP: ffff88003d591e18 R08: 0000000000000000 R09: ffffffff8152fa6c
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R10: 0000000000000000 R11: 0000000000000300 R12: ffff88003b8f9538
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R13: ffffffff8161d0c0 R14: ffff88003b8f9d50 R15: ffff88003c69f908
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FS: 00007f97eb18c720(0000) GS:ffff88003bd00000(0000) knlGS:0000000000000000
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CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
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CR2: 0000000000000008 CR3: 000000003d47a000 CR4: 00000000000006e0
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DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
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DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
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Process keyctl (pid: 4354, threadinfo ffff88003d590000, task ffff88003c78a040)
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Stack:
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ffff88003e0ffde0 ffff88003b8f9538 0000000000000001 ffff88003b8f9d50
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ffff88003d591e28 ffffffff810860f0 ffff88003d591e68 ffffffff8117bfea
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ffff88003d591e68 ffffffff00000000 ffff88003e0ffde1 ffff88003e0ffde0
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Call Trace:
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[<ffffffff810860f0>] call_rcu_sched+0x10/0x12
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[<ffffffff8117bfea>] user_update+0x8d/0xa2
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[<ffffffff8117723a>] key_create_or_update+0x236/0x270
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[<ffffffff811789b1>] sys_add_key+0x123/0x17e
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[<ffffffff813b84bb>] system_call_fastpath+0x16/0x1b
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Signed-off-by: David Howells <dhowells@redhat.com>
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Acked-by: Jeff Layton <jlayton@redhat.com>
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Acked-by: Neil Horman <nhorman@redhat.com>
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Acked-by: Steve Dickson <steved@redhat.com>
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Acked-by: James Morris <jmorris@namei.org>
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Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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---
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security/keys/user_defined.c | 3 ++-
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1 files changed, 2 insertions(+), 1 deletions(-)
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diff --git a/security/keys/user_defined.c b/security/keys/user_defined.c
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index e9aa079..d6781b9 100644
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--- a/security/keys/user_defined.c
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+++ b/security/keys/user_defined.c
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@@ -119,7 +119,8 @@ int user_update(struct key *key, const void *data, size_t datalen)
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key->expiry = 0;
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}
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- call_rcu(&zap->rcu, user_update_rcu_disposal);
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+ if (zap)
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+ call_rcu(&zap->rcu, user_update_rcu_disposal);
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error:
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return ret;
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--
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1.7.7.1
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