netdev - [PATCH net v3 4/7] netdevsim: fix stack-out-of-bounds in nsim_dev_debugfs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [day] [month] [year] [list]

Message-Id: <20200201164322.10080-1-ap420073@gmail.com>
Date:   Sat,  1 Feb 2020 16:43:22 +0000
From:   Taehee Yoo <ap420073@...il.com>
To:     davem@...emloft.net, kuba@...nel.org, netdev@...r.kernel.org
Cc:     ap420073@...il.com
Subject: [PATCH net v3 4/7] netdevsim: fix stack-out-of-bounds in nsim_dev_debugfs_init()

When netdevsim dev is being created, a debugfs directory is created.
The variable "dev_ddir_name" is 16bytes device name pointer and device
name is "netdevsim<dev id>".
The maximum dev id length is 10.
So, 16bytes for device name isn't enough.

Test commands:
    modprobe netdevsim
    echo "1000000000 0" > /sys/bus/netdevsim/new_device

Splat looks like:
[  249.622710][  T900] BUG: KASAN: stack-out-of-bounds in number+0x824/0x880
[  249.623658][  T900] Write of size 1 at addr ffff88804c527988 by task bash/900
[  249.624521][  T900]
[  249.624830][  T900] CPU: 1 PID: 900 Comm: bash Not tainted 5.5.0+ #322
[  249.625691][  T900] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  249.626712][  T900] Call Trace:
[  249.627103][  T900]  dump_stack+0x96/0xdb
[  249.627639][  T900]  ? number+0x824/0x880
[  249.628173][  T900]  print_address_description.constprop.5+0x1be/0x360
[  249.629022][  T900]  ? number+0x824/0x880
[  249.629569][  T900]  ? number+0x824/0x880
[  249.630105][  T900]  __kasan_report+0x12a/0x170
[  249.630717][  T900]  ? number+0x824/0x880
[  249.631201][  T900]  kasan_report+0xe/0x20
[  249.631723][  T900]  number+0x824/0x880
[  249.632235][  T900]  ? put_dec+0xa0/0xa0
[  249.632716][  T900]  ? rcu_read_lock_sched_held+0x90/0xc0
[  249.633392][  T900]  vsnprintf+0x63c/0x10b0
[  249.633983][  T900]  ? pointer+0x5b0/0x5b0
[  249.634543][  T900]  ? mark_lock+0x11d/0xc40
[  249.635200][  T900]  sprintf+0x9b/0xd0
[  249.635750][  T900]  ? scnprintf+0xe0/0xe0
[  249.636370][  T900]  nsim_dev_probe+0x63c/0xbf0 [netdevsim]
[ ... ]

Reviewed-by: Jakub Kicinski <kuba@...nel.org>
Fixes: ab1d0cc004d7 ("netdevsim: change debugfs tree topology")
Signed-off-by: Taehee Yoo <ap420073@...il.com>
---

v2 -> v3:
 - Include Reviewed-by tag

v1 -> v2:
 - Update Fixes tag
 - Do not use arbitary 32 bytes for dev_ddir_name

 drivers/net/netdevsim/dev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/netdevsim/dev.c b/drivers/net/netdevsim/dev.c
index 06b178be3017..273a24245d0b 100644
--- a/drivers/net/netdevsim/dev.c
+++ b/drivers/net/netdevsim/dev.c
@@ -73,7 +73,7 @@ static const struct file_operations nsim_dev_take_snapshot_fops = {
 
 static int nsim_dev_debugfs_init(struct nsim_dev *nsim_dev)
 {
-	char dev_ddir_name[16];
+	char dev_ddir_name[sizeof(DRV_NAME) + 10];
 
 	sprintf(dev_ddir_name, DRV_NAME "%u", nsim_dev->nsim_bus_dev->dev.id);
 	nsim_dev->ddir = debugfs_create_dir(dev_ddir_name, nsim_dev_ddir);
-- 
2.17.1