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netdevsim: fix stack-out-of-bounds in nsim_dev_debugfs_init()

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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@kernel.org>
Fixes: ab1d0cc004 ("netdevsim: change debugfs tree topology")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Taehee Yoo 2020-02-01 16:43:22 +00:00 committed by Jakub Kicinski
parent 8526ad9646
commit 6fb8852b12
1 changed files with 1 additions and 1 deletions
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2
drivers/net/netdevsim/dev.c
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@ -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);