| Message ID | 20211004121438.1839-1-claudiajkang@gmail.com |
|---|---|
| State | Accepted |
| Delegated to: | Pablo Neira |
| Headers | show |
| Series | [nf,v2] netfilter: xt_IDLETIMER: fix panic that occurs when timer_type has garbage value | expand |
Juhee Kang <claudiajkang@gmail.com> wrote: > Currently, when the rule related to IDLETIMER is added, idletimer_tg timer > structure is initialized by kmalloc on executing idletimer_tg_create > function. However, in this process timer->timer_type is not defined to > a specific value. Thus, timer->timer_type has garbage value and it occurs > kernel panic. So, this commit fixes the panic by initializing > timer->timer_type using kzalloc instead of kmalloc. > > Test commands: > # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test > $ cat /sys/class/xt_idletimer/timers/test > Killed Reviewed-by: Florian Westphal <fw@strlen.de>
On Mon, Oct 04, 2021 at 09:14:38PM +0900, Juhee Kang wrote: > Currently, when the rule related to IDLETIMER is added, idletimer_tg timer > structure is initialized by kmalloc on executing idletimer_tg_create > function. However, in this process timer->timer_type is not defined to > a specific value. Thus, timer->timer_type has garbage value and it occurs > kernel panic. So, this commit fixes the panic by initializing > timer->timer_type using kzalloc instead of kmalloc. Applied, thanks.
diff --git a/net/netfilter/xt_IDLETIMER.c b/net/netfilter/xt_IDLETIMER.c index 7b2f359bfce4..2f7cf5ecebf4 100644 --- a/net/netfilter/xt_IDLETIMER.c +++ b/net/netfilter/xt_IDLETIMER.c @@ -137,7 +137,7 @@ static int idletimer_tg_create(struct idletimer_tg_info *info) { int ret; - info->timer = kmalloc(sizeof(*info->timer), GFP_KERNEL); + info->timer = kzalloc(sizeof(*info->timer), GFP_KERNEL); if (!info->timer) { ret = -ENOMEM; goto out;
Currently, when the rule related to IDLETIMER is added, idletimer_tg timer structure is initialized by kmalloc on executing idletimer_tg_create function. However, in this process timer->timer_type is not defined to a specific value. Thus, timer->timer_type has garbage value and it occurs kernel panic. So, this commit fixes the panic by initializing timer->timer_type using kzalloc instead of kmalloc. Test commands: # iptables -A OUTPUT -j IDLETIMER --timeout 1 --label test $ cat /sys/class/xt_idletimer/timers/test Killed Splat looks like: BUG: KASAN: user-memory-access in alarm_expires_remaining+0x49/0x70 Read of size 8 at addr 0000002e8c7bc4c8 by task cat/917 CPU: 12 PID: 917 Comm: cat Not tainted 5.14.0+ #3 79940a339f71eb14fc81aee1757a20d5bf13eb0e Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Call Trace: dump_stack_lvl+0x6e/0x9c kasan_report.cold+0x112/0x117 ? alarm_expires_remaining+0x49/0x70 __asan_load8+0x86/0xb0 alarm_expires_remaining+0x49/0x70 idletimer_tg_show+0xe5/0x19b [xt_IDLETIMER 11219304af9316a21bee5ba9d58f76a6b9bccc6d] dev_attr_show+0x3c/0x60 sysfs_kf_seq_show+0x11d/0x1f0 ? device_remove_bin_file+0x20/0x20 kernfs_seq_show+0xa4/0xb0 seq_read_iter+0x29c/0x750 kernfs_fop_read_iter+0x25a/0x2c0 ? __fsnotify_parent+0x3d1/0x570 ? iov_iter_init+0x70/0x90 new_sync_read+0x2a7/0x3d0 ? __x64_sys_llseek+0x230/0x230 ? rw_verify_area+0x81/0x150 vfs_read+0x17b/0x240 ksys_read+0xd9/0x180 ? vfs_write+0x460/0x460 ? do_syscall_64+0x16/0xc0 ? lockdep_hardirqs_on+0x79/0x120 __x64_sys_read+0x43/0x50 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f0cdc819142 Code: c0 e9 c2 fe ff ff 50 48 8d 3d 3a ca 0a 00 e8 f5 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24 RSP: 002b:00007fff28eee5b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007f0cdc819142 RDX: 0000000000020000 RSI: 00007f0cdc032000 RDI: 0000000000000003 RBP: 00007f0cdc032000 R08: 00007f0cdc031010 R09: 0000000000000000 R10: 0000000000000022 R11: 0000000000000246 R12: 00005607e9ee31f0 R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000 Fixes: 68983a354a65 ("netfilter: xtables: Add snapshot of hardidletimer target") Signed-off-by: Juhee Kang <claudiajkang@gmail.com> --- v1->v2: - change fix tag hash net/netfilter/xt_IDLETIMER.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)