On Fri, May 17, 2013, at 0:05, Greg KH wrote: > On Fri, May 10, 2013 at 11:41:46PM +0200, Alexander van Heukelum wrote: > > Hi Greg, Al, > > > > The patch that went into mainline and was cc'ed to stable assumes that > > 2cf09666 "make SYSCALL_DEFINE<n>-generated wrappers do > > asmlinkage_protect... and switch i386 to HAVE_SYSCALL_WRAPPERS, > > killing open-coded uses of asmlinkage_protect() in a bunch of > > syscalls." is also included. I think my original patch would be better > > suited for the stable tree? It's tiny, independent, and it fixes the > > issue. See attached patch... Al, what do you think? > > > > Also: please note that the problem was introduced in v3.9, so this is > > the only stable tree that should get this patch. > > I really don't understand, should I not have included this patch in the > 3.9-stable tree? Should I use something else instead? If so, what is > the git commit id? Or should I add something on top of this one? > > totally confused,
Sorry about that :-/. So... yes, I think the version that Al cc'ed to stable should not be applied. Instead, 3.9-stable should get the version that I originally sent to lkml (before v3.9 was released): https://lkml.org/lkml/2013/3/27/534 It's the minimal fix for v3.9. Releases before v3.9 didn't have the bug. The original version includes asmlinkage_protect directives. They are (at least theoretically) necessary, because i386 asmlinkage functions puts parameters of function calls on the stack and gcc could otherwise reuse this stack space. That would cause the vm86 syscall to return with changed registers. I did not check if this really happened, but the code generation was changed by adding the directives... I didn't cc that version to stable, because I hoped the fix would make it before the release of v3.9. In the mean time, for v3.10, Al changed the i386 syscall handling: He enabled the syscall wrapper code for i386 and added the asmlinkage_protect directive to the wrappers. He then removed the (now obsoleted) asmlinkage_protect directives from the patch and did the follow-on code simplification. He cc'ed this rebased version to stable, but this version depends on his changes for v3.10. Applying this version means that the stack is not protected for the vm86 syscall. Greetings, Alexander > greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
