Current calculate timeout logic may have overflow if the input timeout value too large. This patch fix this potential overflow issue.
V2: Use local variable instead of call GetPerformanceCounterProperties twice. Also correct some comments. Cc: Michael Kinney <[email protected]> Cc: Ruiyu Ni <[email protected]> Contributed-under: TianoCore Contribution Agreement 1.1 Signed-off-by: Eric Dong <[email protected]> --- UefiCpuPkg/Library/MpInitLib/MpLib.c | 43 +++++++++++++++++++++++++++--------- 1 file changed, 33 insertions(+), 10 deletions(-) diff --git a/UefiCpuPkg/Library/MpInitLib/MpLib.c b/UefiCpuPkg/Library/MpInitLib/MpLib.c index ed1f55e..8394572 100644 --- a/UefiCpuPkg/Library/MpInitLib/MpLib.c +++ b/UefiCpuPkg/Library/MpInitLib/MpLib.c @@ -1001,6 +1001,9 @@ CalculateTimeout ( OUT UINT64 *CurrentTime ) { + UINT64 TimeoutInSeconds; + UINT64 TimestampCounterFreq; + // // Read the current value of the performance counter // @@ -1016,16 +1019,36 @@ CalculateTimeout ( // // GetPerformanceCounterProperties () returns the timestamp counter's frequency - // in Hz. So multiply the return value with TimeoutInMicroseconds and then divide - // it by 1,000,000, to get the number of ticks for the timeout value. - // - return DivU64x32 ( - MultU64x64 ( - GetPerformanceCounterProperties (NULL, NULL), - TimeoutInMicroseconds - ), - 1000000 - ); + // in Hz. + // + TimestampCounterFreq = GetPerformanceCounterProperties (NULL, NULL); + + // + // Check the potential overflow before calculate the number of ticks for the timeout value. + // + if (DivU64x64Remainder (MAX_UINT64, TimeoutInMicroseconds, NULL) < TimestampCounterFreq) { + // + // Convert microseconds into seconds if direct multiplication overflows + // + TimeoutInSeconds = DivU64x32 (TimeoutInMicroseconds, 1000000); + // + // Assertion if the final tick count exceeds MAX_UINT64 + // + ASSERT (DivU64x64Remainder (MAX_UINT64, TimeoutInSeconds, NULL) >= TimestampCounterFreq); + return MultU64x64 (TimestampCounterFreq, TimeoutInSeconds); + } else { + // + // No overflow case, multiply the return value with TimeoutInMicroseconds and then divide + // it by 1,000,000, to get the number of ticks for the timeout value. + // + return DivU64x32 ( + MultU64x64 ( + TimestampCounterFreq, + TimeoutInMicroseconds + ), + 1000000 + ); + } } /** -- 2.7.0.windows.1 _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
