From 53020fe81eecd0b7be295868ce5850ef8f41074e Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 13 May 2009 21:26:19 +0200 Subject: perf_counter: Fix perf_output_copy() WARN to account for overflow The simple reservation test in perf_output_copy() failed to take unsigned int overflow into account, fix this. [ Impact: fix false positive warning with more than 4GB of profiling data ] Signed-off-by: Peter Zijlstra Cc: Paul Mackerras Cc: Corey Ashford LKML-Reference: Signed-off-by: Ingo Molnar --- kernel/perf_counter.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'kernel/perf_counter.c') diff --git a/kernel/perf_counter.c b/kernel/perf_counter.c index ff166c11b69a..985be0b662af 100644 --- a/kernel/perf_counter.c +++ b/kernel/perf_counter.c @@ -1927,7 +1927,11 @@ static void perf_output_copy(struct perf_output_handle *handle, handle->offset = offset; - WARN_ON_ONCE(handle->offset > handle->head); + /* + * Check we didn't copy past our reservation window, taking the + * possible unsigned int wrap into account. + */ + WARN_ON_ONCE(((int)(handle->head - handle->offset)) < 0); } #define perf_output_put(handle, x) \ -- cgit v1.2.2