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Bug 1411

Summary: Quaternion product crashes if EIGEN_DONT_ALIGN_STATICALLY is defined
Product: Eigen Reporter: Shuntaro Yamazaki <shuntaraw>
Component: GeometryAssignee: Nobody <eigen.nobody>
Severity: Crash CC: chtz, gael.guennebaud, hauke.heibel, jacob.benoit.1
Priority: High    
Version: 3.4 (development)   
Hardware: x86 - SSE   
OS: All   
Description Flags
Patch none

Description Shuntaro Yamazaki 2017-03-28 03:50:51 UTC
Created attachment 783 [details]

SSE intrinsics can be called with unaligned pointers in quat_product::run, causing SegFault. The same applies to quat_conj::run.

$ cat qprod.cpp
#include <Eigen/Geometry>
int main() {
    Eigen::Quaterniond q1 = Eigen::Quaterniond(1,0,0,0);
    Eigen::Quaterniond q2 = Eigen::Quaterniond(1,0,0,0);
    Eigen::Quaterniond q = q1 * q2;
    return q.norm();

$ clang++ --version
clang version 3.7.0 (trunk 239477)
Target: x86_64-unknown-linux-gnu

$ clang++ -I. -DEIGEN_DONT_ALIGN_STATICALLY qprod.cpp

$ ./a.out 
Segmentation fault

Note that the above code may not cause SegFault if on-stack Quaternion objects happen to be 16-byte aligned. 

The issue seems to exist in the latest stable and development branches, and is solved by an attached patch. 

Comment 1 Shuntaro Yamazaki 2017-05-09 13:02:59 UTC
Can anyone take a look at this report?
Comment 2 Shuntaro Yamazaki 2017-05-09 13:03:20 UTC
Can anyone take a look at this report?
Comment 3 Gael Guennebaud 2017-06-07 08:12:19 UTC
Thank you for the report and patch that I adapted to be more general: (devel) (3.3)
Comment 4 Nobody 2019-12-04 16:55:02 UTC
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