Commit a8772fad authored by Tetsuo Handa's avatar Tetsuo Handa

tomoyo: Use atomic_t for statistics counter

syzbot is reporting that there is a race at tomoyo_stat_update() [1].
Although it is acceptable to fail to track exact number of times policy
was updated, convert to atomic_t because this is not a hot path.

[1] https://syzkaller.appspot.com/bug?id=a4d7b973972eeed410596e6604580e0133b0fc04Reported-by: default avatarsyzbot <syzbot+efea72d4a0a1d03596cd@syzkaller.appspotmail.com>
Signed-off-by: default avatarTetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
parent 738d2902
...@@ -2322,9 +2322,9 @@ static const char * const tomoyo_memory_headers[TOMOYO_MAX_MEMORY_STAT] = { ...@@ -2322,9 +2322,9 @@ static const char * const tomoyo_memory_headers[TOMOYO_MAX_MEMORY_STAT] = {
[TOMOYO_MEMORY_QUERY] = "query message:", [TOMOYO_MEMORY_QUERY] = "query message:",
}; };
/* Timestamp counter for last updated. */
static unsigned int tomoyo_stat_updated[TOMOYO_MAX_POLICY_STAT];
/* Counter for number of updates. */ /* Counter for number of updates. */
static atomic_t tomoyo_stat_updated[TOMOYO_MAX_POLICY_STAT];
/* Timestamp counter for last updated. */
static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT]; static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT];
/** /**
...@@ -2336,10 +2336,7 @@ static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT]; ...@@ -2336,10 +2336,7 @@ static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT];
*/ */
void tomoyo_update_stat(const u8 index) void tomoyo_update_stat(const u8 index)
{ {
/* atomic_inc(&tomoyo_stat_updated[index]);
* I don't use atomic operations because race condition is not fatal.
*/
tomoyo_stat_updated[index]++;
tomoyo_stat_modified[index] = ktime_get_real_seconds(); tomoyo_stat_modified[index] = ktime_get_real_seconds();
} }
...@@ -2360,7 +2357,7 @@ static void tomoyo_read_stat(struct tomoyo_io_buffer *head) ...@@ -2360,7 +2357,7 @@ static void tomoyo_read_stat(struct tomoyo_io_buffer *head)
for (i = 0; i < TOMOYO_MAX_POLICY_STAT; i++) { for (i = 0; i < TOMOYO_MAX_POLICY_STAT; i++) {
tomoyo_io_printf(head, "Policy %-30s %10u", tomoyo_io_printf(head, "Policy %-30s %10u",
tomoyo_policy_headers[i], tomoyo_policy_headers[i],
tomoyo_stat_updated[i]); atomic_read(&tomoyo_stat_updated[i]));
if (tomoyo_stat_modified[i]) { if (tomoyo_stat_modified[i]) {
struct tomoyo_time stamp; struct tomoyo_time stamp;
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment