[linuxsh-dev] Unaligned access crash in signal handlers

[Denis D. <ddo...@po...>]

Hello Niibe-san,

I have been getting rare crashes in Linux 2.4.0 when handling SIGALRM
signals. I have managed to trace the problem down and it seems that the
sigreturn trap code is not getting flushed to the signal frame
sometimes. The problem goes away completely if I do a flush_cache_all
instead of flush_icache_range. I have attached a patch that does this. I
cannot see anything wrong with the current flush_icache_range usage but
suspect it is broken. The flush_cache_all is complete overkill so would
be very keen to hear if you have a fix for flush_icache_range.

The problem is very difficult to reproduce in a test program. It only
happens when parts of the stack have already been mapped into the
address cache and the signal handler is very short. I have a compiled
version of lrz from the lrzsz package that consistently crashes 2.4.0
everytime it is run. I can send this to you if you want.

Regards,
Denis