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locking/lockdep: Fix buffer overrun problem in stack_trace[]
commitd91f305726
upstream. If the lockdep code is really running out of the stack_trace entries, it is likely that buffer overrun can happen and the data immediately after stack_trace[] will be corrupted. If there is less than LOCK_TRACE_SIZE_IN_LONGS entries left before the call to save_trace(), the max_entries computation will leave it with a very large positive number because of its unsigned nature. The subsequent call to stack_trace_save() will then corrupt the data after stack_trace[]. Fix that by changing max_entries to a signed integer and check for negative value before calling stack_trace_save(). Signed-off-by: Waiman Long <longman@redhat.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes:12593b7467
("locking/lockdep: Reduce space occupied by stack traces") Link: https://lkml.kernel.org/r/20191220135128.14876-1-longman@redhat.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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7dec71eba7
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1 changed files with 3 additions and 4 deletions
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@ -482,7 +482,7 @@ static struct lock_trace *save_trace(void)
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struct lock_trace *trace, *t2;
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struct hlist_head *hash_head;
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u32 hash;
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unsigned int max_entries;
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int max_entries;
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BUILD_BUG_ON_NOT_POWER_OF_2(STACK_TRACE_HASH_SIZE);
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BUILD_BUG_ON(LOCK_TRACE_SIZE_IN_LONGS >= MAX_STACK_TRACE_ENTRIES);
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@ -490,10 +490,8 @@ static struct lock_trace *save_trace(void)
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trace = (struct lock_trace *)(stack_trace + nr_stack_trace_entries);
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max_entries = MAX_STACK_TRACE_ENTRIES - nr_stack_trace_entries -
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LOCK_TRACE_SIZE_IN_LONGS;
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trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
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if (nr_stack_trace_entries >= MAX_STACK_TRACE_ENTRIES -
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LOCK_TRACE_SIZE_IN_LONGS - 1) {
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if (max_entries <= 0) {
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if (!debug_locks_off_graph_unlock())
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return NULL;
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@ -502,6 +500,7 @@ static struct lock_trace *save_trace(void)
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return NULL;
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}
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trace->nr_entries = stack_trace_save(trace->entries, max_entries, 3);
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hash = jhash(trace->entries, trace->nr_entries *
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sizeof(trace->entries[0]), 0);
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