diff options
| author | Chenbo Feng <fengc@google.com> | 2017-03-23 13:51:24 -0700 |
|---|---|---|
| committer | Chenbo Feng <fengc@google.com> | 2017-03-23 16:52:48 -0700 |
| commit | f0faedd6b468777f3bb5834f97100794d562c8b7 (patch) | |
| tree | 9ad6e99c3403cbaebd58851994ae749e3b5c87a9 | |
| parent | e953f89b8563efe0b92f70033d237874c43d4a3d (diff) | |
fix the deadlock in xt_qtaguid when enable DDEBUG
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>
| -rw-r--r-- | net/netfilter/xt_qtaguid.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/net/netfilter/xt_qtaguid.c b/net/netfilter/xt_qtaguid.c index 3bf0c59dab2f..0f5628a59917 100644 --- a/net/netfilter/xt_qtaguid.c +++ b/net/netfilter/xt_qtaguid.c @@ -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; } |