From 6fb8852b1298200da39bd85788bc5755d1d56f32 Mon Sep 17 00:00:00 2001 From: Taehee Yoo Date: Sat, 1 Feb 2020 16:43:22 +0000 Subject: [PATCH 1/1] 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". 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 Fixes: ab1d0cc004d7 ("netdevsim: change debugfs tree topology") Signed-off-by: Taehee Yoo Signed-off-by: Jakub Kicinski --- 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 06b178b..273a242 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); -- 2.7.4