Re: [PATCH 1/1 linux-next] ipc/msg.c: fix memory leak in do_msgsnd()

From: Manfred Spraul
Date: Sun Jul 31 2016 - 10:39:05 EST

Hi Fabian,

On 07/29/2016 10:15 AM, Fabian Frederick wrote:
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 ........
[<ffffffff818e2c43>] kmemleak_alloc+0x23/0x40
[<ffffffff81177f31>] kmem_cache_alloc_trace+0xe1/0x180
[<ffffffff812d42af>] selinux_msg_queue_alloc_security+0x3f/0xd0
[<ffffffff812cc6be>] security_msg_queue_alloc+0x2e/0x40
[<ffffffff812b94ee>] newque+0x4e/0x150
[<ffffffff812b8cb9>] ipcget+0x159/0x1b0
[<ffffffff812b98d9>] SyS_msgget+0x39/0x40
[<ffffffff818e7bdb>] entry_SYSCALL_64_fastpath+0x13/0x8f
[<ffffffffffffffff>] 0xffffffffffffffff

ipc_rcu_free() was given to ipc_rcu_putref() instead of msg_rcu_free()
which does security cleaning.
Good catch!

From a quick look:
- The same bug appears to exist in sem.c. Do you want to fix it as well?
- Did you check when it was introduced? I would add cc stable.