evie/android_kernel_oneplus_msm8998
1
0
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

fix the deadlock in xt_qtaguid when enable DDEBUG

Browse source 
When DDEBUG is enabled, the prdebug_full_state() function will try to
recursively aquire the spinlock of sock_tag_list and causing deadlock. A
check statement is added before it aquire the spinlock to differentiate
the behavior depend on the caller of the function.

Bug: 36559739
Test: Compile and run test under system/extra/test/iptables/
Change-Id: Ie3397fbaa207e14fe214d47aaf5e8ca1f4a712ee
Signed-off-by: Chenbo Feng <fengc@google.com>
This commit is contained in:
Chenbo Feng 2017-03-23 13:51:24 -07:00
parent e953f89b85
commit f0faedd6b4
1 changed files with 14 additions and 10 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
net/netfilter/xt_qtaguid.c
View file

@ -1814,8 +1814,11 @@ ret_res:
}
#ifdef DDEBUG
/* This function is not in xt_qtaguid_print.c because of locks visibility */
static void prdebug_full_state(int indent_level, const char *fmt, ...)
/*
* This function is not in xt_qtaguid_print.c because of locks visibility.
* The lock of sock_tag_list must be aquired before calling this function
*/
static void prdebug_full_state_locked(int indent_level, const char *fmt, ...)
{
va_list args;
char *fmt_buff;
@ -1836,16 +1839,12 @@ static void prdebug_full_state(int indent_level, const char *fmt, ...)
kfree(buff);
va_end(args);
spin_lock_bh(&sock_tag_list_lock);
prdebug_sock_tag_tree(indent_level, &sock_tag_tree);
spin_unlock_bh(&sock_tag_list_lock);
spin_lock_bh(&sock_tag_list_lock);
spin_lock_bh(&uid_tag_data_tree_lock);
prdebug_uid_tag_data_tree(indent_level, &uid_tag_data_tree);
prdebug_proc_qtu_data_tree(indent_level, &proc_qtu_data_tree);
spin_unlock_bh(&uid_tag_data_tree_lock);
spin_unlock_bh(&sock_tag_list_lock);
spin_lock_bh(&iface_stat_list_lock);
prdebug_iface_stat_list(indent_level, &iface_stat_list);
@ -1854,7 +1853,7 @@ static void prdebug_full_state(int indent_level, const char *fmt, ...)
pr_debug("qtaguid: %s(): }\n", __func__);
}
#else
static void prdebug_full_state(int indent_level, const char *fmt, ...) {}
static void prdebug_full_state_locked(int indent_level, const char *fmt, ...) {}
#endif
struct proc_ctrl_print_info {
@ -1977,8 +1976,11 @@ static int qtaguid_ctrl_proc_show(struct seq_file *m, void *v)
(u64)atomic64_read(&qtu_events.match_no_sk),
(u64)atomic64_read(&qtu_events.match_no_sk_file));
/* Count the following as part of the last item_index */
prdebug_full_state(0, "proc ctrl");
/* Count the following as part of the last item_index. No need
* to lock the sock_tag_list here since it is already locked when
* starting the seq_file operation
*/
prdebug_full_state_locked(0, "proc ctrl");
}
return 0;
@ -2887,8 +2889,10 @@ static int qtudev_release(struct inode *inode, struct file *file)
sock_tag_tree_erase(&st_to_free_tree);
prdebug_full_state(0, "%s(): pid=%u tgid=%u", __func__,
spin_lock_bh(&sock_tag_list_lock);
prdebug_full_state_locked(0, "%s(): pid=%u tgid=%u", __func__,
current->pid, current->tgid);
spin_unlock_bh(&sock_tag_list_lock);
return 0;
}