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[profile] Prevent potential division by zero 

Limit the profile sample count to INT_MAX to avoid both signed
overflow and a potential division by zero when updating the stored
mean value.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/71/head
Michael Brown 2018-03-18 18:36:58 +02:00
parent b11ae1d91b
commit ae93064496
1 changed files with 4 additions and 2 deletions
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6
src/core/profile.c
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@ -26,6 +26,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <stdint.h>
#include <stdio.h>
#include <strings.h>
#include <limits.h>
#include <assert.h>
#include <ipxe/isqrt.h>
#include <ipxe/profile.h>
@ -122,8 +123,9 @@ void profile_update ( struct profiler *profiler, unsigned long sample ) {
*/
assert ( ( ( signed ) sample ) >= 0 );
/* Update sample count */
profiler->count++;
/* Update sample count, limiting to avoid signed overflow */
if ( profiler->count < INT_MAX )
profiler->count++;
/* Adjust mean sample value scale if necessary. Skip if
* sample is zero (in which case flsl(sample)-1 would