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| author | Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> | 2020-01-02 12:53:49 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2020-02-05 21:22:41 +0000 |
| commit | 99652ee9c51669706216af7b6a32b4b792263c95 (patch) | |
| tree | 2f0d9c8d24fb081062a71d518425c49c5a46fc90 /security | |
| parent | 81b3fd0cb4216fe3027be8c4b57d68c1c7e0dfb7 (diff) | |
| download | linux-stable-99652ee9c51669706216af7b6a32b4b792263c95.tar.gz linux-stable-99652ee9c51669706216af7b6a32b4b792263c95.tar.bz2 linux-stable-99652ee9c51669706216af7b6a32b4b792263c95.zip | |
tomoyo: Use atomic_t for statistics counter
commit a8772fad0172aeae339144598b809fd8d4823331 upstream.
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=a4d7b973972eeed410596e6604580e0133b0fc04
Reported-by: syzbot <syzbot+efea72d4a0a1d03596cd@syzkaller.appspotmail.com>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'security')
| -rw-r--r-- | security/tomoyo/common.c | 11 |
1 files changed, 4 insertions, 7 deletions
diff --git a/security/tomoyo/common.c b/security/tomoyo/common.c index c36bafbcd77e..1b467381986f 100644 --- a/security/tomoyo/common.c +++ b/security/tomoyo/common.c @@ -2322,9 +2322,9 @@ static const char * const tomoyo_memory_headers[TOMOYO_MAX_MEMORY_STAT] = { [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. */ +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]; /** @@ -2336,10 +2336,7 @@ static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT]; */ void tomoyo_update_stat(const u8 index) { - /* - * I don't use atomic operations because race condition is not fatal. - */ - tomoyo_stat_updated[index]++; + atomic_inc(&tomoyo_stat_updated[index]); tomoyo_stat_modified[index] = ktime_get_real_seconds(); } @@ -2360,7 +2357,7 @@ static void tomoyo_read_stat(struct tomoyo_io_buffer *head) for (i = 0; i < TOMOYO_MAX_POLICY_STAT; i++) { tomoyo_io_printf(head, "Policy %-30s %10u", tomoyo_policy_headers[i], - tomoyo_stat_updated[i]); + atomic_read(&tomoyo_stat_updated[i])); if (tomoyo_stat_modified[i]) { struct tomoyo_time stamp; |