linux-kernel - Re: [PATCH] fmc: Fix possible NULL pointer dereference

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Message-ID: <28aafb84-4d15-0340-66fd-0d4d02c1ecce@huawei.com>
Date:   Mon, 8 Apr 2019 22:42:42 +0800
From:   YueHaibing <yuehaibing@...wei.com>
To:     <gregkh@...uxfoundation.org>, <rubini@...dd.com>,
        <federico.vaga@...n.ch>, <riehecky@...l.gov>
CC:     <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] fmc: Fix possible NULL pointer dereference

+cc Alessandro Rubini <rubini@...dd.com>

On 2019/4/8 22:37, Yue Haibing wrote:
> From: YueHaibing <yuehaibing@...wei.com>
> 
> Syzkaller report this:
> 
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] SMP KASAN PTI
> CPU: 0 PID: 3692 Comm: syz-executor.0 Tainted: G         C        5.0.0+ #5
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014
> RIP: 0010:ff_dev_create+0xf7/0x2e0 [fmc_fakedev]
> Code: 00 e8 4d 2d a7 f6 ba c0 0c 00 00 48 c7 c7 00 20 15 c1 be e8 04 00 00 e8 e7 8e c7 f6 48 8d b8 a8 04 00 00 48 89 fa 48 c1 ea 03 <80> 3c 1a 00 0f 85 90 01 00 00 48 8d 78 50 4c 89 b0 a8 04 00 00 48
> RSP: 0018:ffff8881ea7a78e8 EFLAGS: 00010206
> RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffffffff815c9540
> RDX: 0000000000000095 RSI: ffffc900013ec000 RDI: 00000000000004a8
> RBP: 0000000000000000 R08: ffffed103ee458b8 R09: ffffed103ee458b8
> R10: 0000000000000001 R11: ffffed103ee458b7 R12: ffff8881e4865d80
> R13: dffffc0000000000 R14: ffff8881e4865da0 R15: ffffffffc115b0b0
> FS:  00007fb08a226700(0000) GS:ffff8881f7200000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f6bd5a37890 CR3: 00000001c5632006 CR4: 00000000007606f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
>  ff_init+0x10b/0x3a0 [fmc_fakedev]
>  do_one_initcall+0xbc/0x47d init/main.c:887
>  do_init_module+0x1b5/0x547 kernel/module.c:3456
>  load_module+0x6405/0x8c10 kernel/module.c:3804
>  __do_sys_finit_module+0x162/0x190 kernel/module.c:3898
>  do_syscall_64+0x9f/0x450 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x462e99
> Code: f7 d8 64 89 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
> RSP: 002b:00007fb08a225c58 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
> RAX: ffffffffffffffda RBX: 000000000073bf00 RCX: 0000000000462e99
> RDX: 0000000000000000 RSI: 0000000020000100 RDI: 0000000000000003
> RBP: 00007fb08a225c70 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007fb08a2266bc
> R13: 00000000004bcefa R14: 00000000006f6fb0 R15: 0000000000000004
> Modules linked in: fmc_fakedev(+) fmc iptable_security iptable_raw iptable_mangle iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_filter bpfilter ip6_vti ip_vti ip_gre ipip sit tunnel4 ip_tunnel hsr veth netdevsim vxcan batman_adv cfg80211 rfkill chnl_net caif nlmon dummy team bonding vcan bridge stp llc ip6_gre gre ip6_tunnel tunnel6 tun joydev mousedev ppdev tpm kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel aesni_intel ide_pci_generic piix aes_x86_64 crypto_simd cryptd ide_core psmouse glue_helper input_leds intel_agp serio_raw intel_gtt i2c_piix4 ata_generic agpgart pata_acpi rtc_cmos parport_pc floppy parport sch_fq_codel ip_tables x_tables sha1_ssse3 sha1_generic ipv6 [last unloaded: lib80211]
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> ---[ end trace 297e0e50d0ab9883 ]---
> 
> If kmemdup failed, we should rollback all the alloced resources.
> 
> Reported-by: Hulk Robot <hulkci@...wei.com>
> Fixes: 6c62a895e572 ("FMC: add a software carrier driver")
> Signed-off-by: YueHaibing <yuehaibing@...wei.com>
> ---
>  drivers/fmc/fmc-fakedev.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/fmc/fmc-fakedev.c b/drivers/fmc/fmc-fakedev.c
> index 941d093..43d99fe 100644
> --- a/drivers/fmc/fmc-fakedev.c
> +++ b/drivers/fmc/fmc-fakedev.c
> @@ -273,15 +273,18 @@ static struct ff_dev *ff_dev_create(void)
>  	ff->dev.release = ff_dev_release;
>  
>  	ret = device_register(&ff->dev);
> -	if (ret < 0) {
> -		put_device(&ff->dev);
> -		return ERR_PTR(ret);
> -	}
> +	if (ret < 0)
> +		goto failed_register;
>  
>  	/* Create fmc structures that refer to this new "hw" device */
>  	for (i = 0; i < ff_nr_dev; i++) {
>  		fmc = kmemdup(&ff_template_fmc, sizeof(ff_template_fmc),
>  			      GFP_KERNEL);
> +		if (!fmc) {
> +			ret = -ENOMEM
> +			goto free_fmc;
> +		}
> +
>  		fmc->hwdev = &ff->dev;
>  		fmc->carrier_data = ff;
>  		fmc->nr_slots = ff_nr_dev;
> @@ -294,6 +297,13 @@ static struct ff_dev *ff_dev_create(void)
>  		ff_template_fmc.device_id++;
>  	}
>  	return ff;
> +
> +free_fmc:
> +	for (i--; i >= 0; i--)
> +		kfree(ff->fmc[i]);
> +failed_register:
> +	put_device(&ff->dev);
> +	return ERR_PTR(ret);
>  }
>  
>  /* init and exit */
>