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Subject[PATCH 4.4 034/241] ppp: deflate: Fix possible crash in deflate_init
Date
From: YueHaibing <yuehaibing@huawei.com>

[ Upstream commit 3ebe1bca58c85325c97a22d4fc3f5b5420752e6f ]

BUG: unable to handle kernel paging request at ffffffffa018f000
PGD 3270067 P4D 3270067 PUD 3271063 PMD 2307eb067 PTE 0
Oops: 0000 [#1] PREEMPT SMP
CPU: 0 PID: 4138 Comm: modprobe Not tainted 5.1.0-rc7+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014
RIP: 0010:ppp_register_compressor+0x3e/0xd0 [ppp_generic]
Code: 98 4a 3f e2 48 8b 15 c1 67 00 00 41 8b 0c 24 48 81 fa 40 f0 19 a0
75 0e eb 35 48 8b 12 48 81 fa 40 f0 19 a0 74
RSP: 0018:ffffc90000d93c68 EFLAGS: 00010287
RAX: ffffffffa018f000 RBX: ffffffffa01a3000 RCX: 000000000000001a
RDX: ffff888230c750a0 RSI: 0000000000000000 RDI: ffffffffa019f000
RBP: ffffc90000d93c80 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffa0194080
R13: ffff88822ee1a700 R14: 0000000000000000 R15: ffffc90000d93e78
FS: 00007f2339557540(0000) GS:ffff888237a00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffffffa018f000 CR3: 000000022bde4000 CR4: 00000000000006f0
Call Trace:
? 0xffffffffa01a3000
deflate_init+0x11/0x1000 [ppp_deflate]
? 0xffffffffa01a3000
do_one_initcall+0x6c/0x3cc
? kmem_cache_alloc_trace+0x248/0x3b0
do_init_module+0x5b/0x1f1
load_module+0x1db1/0x2690
? m_show+0x1d0/0x1d0
__do_sys_finit_module+0xc5/0xd0
__x64_sys_finit_module+0x15/0x20
do_syscall_64+0x6b/0x1d0
entry_SYSCALL_64_after_hwframe+0x49/0xbe

If ppp_deflate fails to register in deflate_init,
module initialization failed out, however
ppp_deflate_draft may has been regiestred and not
unregistered before return.
Then the seconed modprobe will trigger crash like this.

Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: YueHaibing <yuehaibing@huawei.com>
Acked-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ppp/ppp_deflate.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)

--- a/drivers/net/ppp/ppp_deflate.c
+++ b/drivers/net/ppp/ppp_deflate.c
@@ -610,12 +610,20 @@ static struct compressor ppp_deflate_dra

static int __init deflate_init(void)
{
- int answer = ppp_register_compressor(&ppp_deflate);
- if (answer == 0)
- printk(KERN_INFO
- "PPP Deflate Compression module registered\n");
- ppp_register_compressor(&ppp_deflate_draft);
- return answer;
+ int rc;
+
+ rc = ppp_register_compressor(&ppp_deflate);
+ if (rc)
+ return rc;
+
+ rc = ppp_register_compressor(&ppp_deflate_draft);
+ if (rc) {
+ ppp_unregister_compressor(&ppp_deflate);
+ return rc;
+ }
+
+ pr_info("PPP Deflate Compression module registered\n");
+ return 0;
}

static void __exit deflate_cleanup(void)

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