Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 18 Mar 2015 19:31:33 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH v3 1/2] x86_64,signal: Fix SS handling for signals delivered to 64-bit programs |
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On 03/18, Cyrill Gorcunov wrote: > > On Wed, Mar 18, 2015 at 06:48:43PM +0100, Oleg Nesterov wrote: > > > > Shot in a dark afer a quick grep: restore_gpregs() should initialize ->ss? > > It hasn't been needed earlier, if this would help it means abi is broken, no? :) > Otherwise I don't understand what's happening.
until this commit the kernel simply forgot to restore ->ss in sigreturn().
after this commit, if your rt_sigframe has garbage in ->ss then SIGSEGV is clear.
> > perhaps something like below... obviously uncompiled/untested. > > > > And my grep can't find the definition of UserX86RegsEntry in crtools... > > Perhaps the change below needs CPREG1(ss, anothername). > > > > Seriously, where is UserX86RegsEntry? > > It's in protobif/core-x86.proto, welcome to protobuf hell.
Still can't find UserX86RegsEntry... OK, perhaps it comes from user_x86_regs_entry in protobuf/core-x86.proto. Then I guess the patch I sent can be compiled at least ;)
> > > > > Oleg. > > > > > > --- a/arch/x86/crtools.c > > +++ b/arch/x86/crtools.c > > @@ -475,6 +475,7 @@ int restore_gpregs(struct rt_sigframe *f, UserX86RegsEntry *r) > > CPREG2(rip, ip); > > CPREG2(eflags, flags); > > CPREG1(cs); > > + CPREG1(ss); > > CPREG1(gs); > > CPREG1(fs); > > > > diff --git a/arch/x86/include/asm/restorer.h b/arch/x86/include/asm/restorer.h > > index 70199fb..c04fb94 100644 > > --- a/arch/x86/include/asm/restorer.h > > +++ b/arch/x86/include/asm/restorer.h > > @@ -53,7 +53,7 @@ struct rt_sigcontext { > > unsigned short cs; > > unsigned short gs; > > unsigned short fs; > > - unsigned short __pad0; > > + unsigned short ss; > > unsigned long err; > > unsigned long trapno; > > unsigned long oldmask; > > > > Cyrill
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