Description of problem: Following text has been replicated verbatim from original patch submission from John Byrne. See URL above. Currently, the SMP interrupt code generated by the macros BUILD_SMP_INTERRUPT and BUILD_SMP_TIMER_INTERRUPT push the positive interrupt vector number on the stack. If the correct signal is pending on the process and %eax happens to have the correct value, do_signal() can be spoofed into adjusting %eax and %eip with almost certainly bad results. For example, trying to do a "strace -p" the following program will result in its dumping core with an illegal instruction. int main(void) { int i; asm ( "mov %1,%0\n\t" "1:\t" "cmp %1,%0\n\t" "rep;nop\n\t" "je 1b\n\t" :"=&a" (i) :"i" (-512)); return i; } I suspect what was wanted was to subtract 256, as is done in BUILD_IRQ, to make the values negative, but leave the vector available in %al, so I offer the following patch against 2.4.10-pre2 to do so. (The 2.2.x code simply pushes -1. I don't see anything that uses the vector for these interrupt, so this should work. However, I assume the change was made so the vector number would be available on the stack, perhaps for debugging.) This has only been tested by me on my SMP box, but... (I don't want to complete that sentence with words I might be forced to regret for some reason.) Version-Release number of selected component (if applicable): LAS 2.1 Red Hat 7.1 How reproducible: Absolutely. Steps to Reproduce: 1. See URL above for sample program Actual results: Expected results: Additional info:
the most current 7.1 kernel is 2.4.18-24.... I'd expect it to be fixed there....
This bug was found in RedHat 7.1. The patch has been incorporated in Linux Advanced Server 2.1, as I verified from the source code. As our upgrade plans are to go from 7.1 to LAS 2.1, I don't think any further action is necessary on this bug; the fix is to upgrade.