Hi guys,
On Sun, Aug 14, 2016 at 10:07:45PM +0200, Greg Kroah-Hartman wrote:
> 3.14-stable review patch. If anyone has any objections, please let me know.
>
> ------------------
>
> From: Fabian Frederick <fabf@xxxxxxxxx>
>
> commit 9b24fef9f0410fb5364245d6cc2bd044cc064007 upstream.
>
> Commit 53dad6d3a8e5 ("ipc: fix race with LSMs") updated ipc_rcu_putref()
> to receive rcu freeing function but used generic ipc_rcu_free() instead
> of msg_rcu_free() which does security cleaning.
>
> Running LTP msgsnd06 with kmemleak gives the following:
>
> cat /sys/kernel/debug/kmemleak
>
> unreferenced object 0xffff88003c0a11f8 (size 8):
> comm "msgsnd06", pid 1645, jiffies 4294672526 (age 6.549s)
> hex dump (first 8 bytes):
> 1b 00 00 00 01 00 00 00 ........
> backtrace:
> kmemleak_alloc+0x23/0x40
> kmem_cache_alloc_trace+0xe1/0x180
> selinux_msg_queue_alloc_security+0x3f/0xd0
> security_msg_queue_alloc+0x2e/0x40
> newque+0x4e/0x150
> ipcget+0x159/0x1b0
> SyS_msgget+0x39/0x40
> entry_SYSCALL_64_fastpath+0x13/0x8f
>
> Manfred Spraul suggested to fix sem.c as well and Davidlohr Bueso to
> only use ipc_rcu_free in case of security allocation failure in newary()
>
> Fixes: 53dad6d3a8e ("ipc: fix race with LSMs")
> Link: http://lkml.kernel.org/r/1470083552-22966-1-git-send-email-fabf@xxxxxxxxx
> Signed-off-by: Fabian Frederick <fabf@xxxxxxxxx>
> Cc: Davidlohr Bueso <dbueso@xxxxxxx>
> Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
The patch above was tagged for stable v3.12+, however it references a fix
that was backported in 3.10.16 as commit e84ca333, so I'm unsure whether
3.10 is affected or not. It *seems* to me that I should replace remaining
instances of ipc_rcu_free with sem_rcu_free in sem.c, and with msg_rcu_free
in msg.c, but I'd prefer a confirmation. For now I'm postponing this fix,
any hint would be much appreciated.
Thanks,
Willy
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