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tomoyo: Use atomic_t for statistics counter
commit a8772fad01
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>
This commit is contained in:
parent
81b3fd0cb4
commit
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1 changed files with 4 additions and 7 deletions
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@ -2322,9 +2322,9 @@ static const char * const tomoyo_memory_headers[TOMOYO_MAX_MEMORY_STAT] = {
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[TOMOYO_MEMORY_QUERY] = "query message:",
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[TOMOYO_MEMORY_QUERY] = "query message:",
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};
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};
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/* Timestamp counter for last updated. */
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static unsigned int tomoyo_stat_updated[TOMOYO_MAX_POLICY_STAT];
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/* Counter for number of updates. */
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/* Counter for number of updates. */
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static atomic_t tomoyo_stat_updated[TOMOYO_MAX_POLICY_STAT];
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/* Timestamp counter for last updated. */
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static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT];
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static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT];
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/**
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/**
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@ -2336,10 +2336,7 @@ static time64_t tomoyo_stat_modified[TOMOYO_MAX_POLICY_STAT];
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*/
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*/
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void tomoyo_update_stat(const u8 index)
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void tomoyo_update_stat(const u8 index)
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{
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{
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/*
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atomic_inc(&tomoyo_stat_updated[index]);
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* I don't use atomic operations because race condition is not fatal.
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*/
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tomoyo_stat_updated[index]++;
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tomoyo_stat_modified[index] = ktime_get_real_seconds();
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tomoyo_stat_modified[index] = ktime_get_real_seconds();
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}
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}
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@ -2360,7 +2357,7 @@ static void tomoyo_read_stat(struct tomoyo_io_buffer *head)
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for (i = 0; i < TOMOYO_MAX_POLICY_STAT; i++) {
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for (i = 0; i < TOMOYO_MAX_POLICY_STAT; i++) {
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tomoyo_io_printf(head, "Policy %-30s %10u",
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tomoyo_io_printf(head, "Policy %-30s %10u",
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tomoyo_policy_headers[i],
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tomoyo_policy_headers[i],
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tomoyo_stat_updated[i]);
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atomic_read(&tomoyo_stat_updated[i]));
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if (tomoyo_stat_modified[i]) {
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if (tomoyo_stat_modified[i]) {
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struct tomoyo_time stamp;
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struct tomoyo_time stamp;
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