Messages in this thread | | | Date | Sun, 6 Jul 2003 18:47:50 +1000 | From | Paul Mackerras <> | Subject | Re: [PATCH 2.5.73] Signal stack fixes #1 introduce PF_SS_ACTIVE |
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Jörn Engel writes:
> The problem is with a broken signal handler, that moves the stack > pointer to nirvana. You get a signal, set up the signal stack, move > the pointer to nirvana, get a signal, set up the signal stack, move > the pointer to nirvana, get a signal, ...
You can get the same effect by doing kill(0, SIGINT) inside a handler for SIGINT. All you seem to be saying is "if you behave stupidly then bad things happen to you". I don't see that this example exposes any bug or vulnerability in the kernel.
> If I was just going down the signal stack, I would be perfectly happy, > but instead the kernel believes each signal is the very first on the > signal stack and sets it up again (and again...) each time.
You had to go to some trouble to get this effect - you had to use an asm statement to change the stack pointer, which is well and truly into "undefined behaviour" territory, and so you deserve all you get. :) It's a very contrived example IMHO.
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