* sigaltstack doesn't round ss.ss_sp as required @ 2012-11-24 15:05 John David Anglin 2012-11-25 21:39 ` [PATCH] parisc: " John David Anglin 0 siblings, 1 reply; 4+ messages in thread From: John David Anglin @ 2012-11-24 15:05 UTC (permalink / raw) To: Parisc List In trying to build the debian libsigsegv2 package, I found that sigaltstack doesn't round ss.ss_sp. The tests intentionally pass an unaligned pointer. This results in the two stack overflow tests failing. According to the Linux manual page: "When a signal handler is invoked on the alternate stack, the kernel automatically aligns the address given in ss.ss_sp to a suitable address boundary for the underlying hardware architecture." The stack address for the signal handler needs to be adjusted to provide for frame marker and stack argument slots. Dave -- John David Anglin dave.anglin@bell.net ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH] parisc: sigaltstack doesn't round ss.ss_sp as required 2012-11-24 15:05 sigaltstack doesn't round ss.ss_sp as required John David Anglin @ 2012-11-25 21:39 ` John David Anglin 2012-11-25 22:07 ` Rolf Eike Beer 0 siblings, 1 reply; 4+ messages in thread From: John David Anglin @ 2012-11-25 21:39 UTC (permalink / raw) To: John David Anglin; +Cc: Helge Deller, Parisc List, James E.J. Bottomley [-- Attachment #1: Type: text/plain, Size: 370 bytes --] On 24-Nov-12, at 10:05 AM, John David Anglin wrote: > In trying to build the debian libsigsegv2 package, I found that > sigaltstack > doesn't round ss.ss_sp. The tests intentionally pass an unaligned > pointer. > This results in the two stack overflow tests failing. The attached patch fixes this issue. Signed-off-by: John David Anglin <dave.anglin@bell.net> [-- Attachment #2: signal.c.d.txt --] [-- Type: text/plain, Size: 778 bytes --] diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c index 594459b..324644d 100644 --- a/arch/parisc/kernel/signal.c +++ b/arch/parisc/kernel/signal.c @@ -188,8 +188,10 @@ get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size) DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n", (unsigned long)ka, sp, frame_size); + /* Align alternate stack and reserve 64 bytes for the signal + handler's frame marker. */ if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp)) - sp = current->sas_ss_sp; /* Stacks grow up! */ + sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */ DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp); return (void __user *) sp; /* Stacks grow up. Fun. */ [-- Attachment #3: Type: text/plain, Size: 45 bytes --] -- John David Anglin dave.anglin@bell.net ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] parisc: sigaltstack doesn't round ss.ss_sp as required 2012-11-25 21:39 ` [PATCH] parisc: " John David Anglin @ 2012-11-25 22:07 ` Rolf Eike Beer 2012-11-25 22:32 ` John David Anglin 0 siblings, 1 reply; 4+ messages in thread From: Rolf Eike Beer @ 2012-11-25 22:07 UTC (permalink / raw) To: John David Anglin; +Cc: Helge Deller, Parisc List, James E.J. Bottomley [-- Attachment #1: Type: text/plain, Size: 1268 bytes --] John David Anglin wrote: > On 24-Nov-12, at 10:05 AM, John David Anglin wrote: > > In trying to build the debian libsigsegv2 package, I found that > > sigaltstack > > doesn't round ss.ss_sp. The tests intentionally pass an unaligned > > pointer. > > This results in the two stack overflow tests failing. > > The attached patch fixes this issue. diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c index 594459b..324644d 100644 --- a/arch/parisc/kernel/signal.c +++ b/arch/parisc/kernel/signal.c @@ -188,8 +188,10 @@ get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size) DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n", (unsigned long)ka, sp, frame_size); + /* Align alternate stack and reserve 64 bytes for the signal + handler's frame marker. */ if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp)) - sp = current->sas_ss_sp; /* Stacks grow up! */ + sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */ DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp); return (void __user *) sp; /* Stacks grow up. Fun. */ What about something like this (entirely untested, but you'll get the idea): sp = round_down(current->sas_ss_sp + 64, 64); Greetings. Eike [-- Attachment #2: This is a digitally signed message part. --] [-- Type: application/pgp-signature, Size: 198 bytes --] ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] parisc: sigaltstack doesn't round ss.ss_sp as required 2012-11-25 22:07 ` Rolf Eike Beer @ 2012-11-25 22:32 ` John David Anglin 0 siblings, 0 replies; 4+ messages in thread From: John David Anglin @ 2012-11-25 22:32 UTC (permalink / raw) To: Rolf Eike Beer; +Cc: Helge Deller, Parisc List, James E.J. Bottomley On 25-Nov-12, at 5:07 PM, Rolf Eike Beer wrote: > John David Anglin wrote: >> On 24-Nov-12, at 10:05 AM, John David Anglin wrote: >>> In trying to build the debian libsigsegv2 package, I found that >>> sigaltstack >>> doesn't round ss.ss_sp. The tests intentionally pass an unaligned >>> pointer. >>> This results in the two stack overflow tests failing. >> >> The attached patch fixes this issue. > > diff --git a/arch/parisc/kernel/signal.c b/arch/parisc/kernel/signal.c > index 594459b..324644d 100644 > --- a/arch/parisc/kernel/signal.c > +++ b/arch/parisc/kernel/signal.c > @@ -188,8 +188,10 @@ get_sigframe(struct k_sigaction *ka, unsigned > long sp, size_t frame_size) > DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n", > (unsigned long)ka, sp, frame_size); > > + /* Align alternate stack and reserve 64 bytes for the signal > + handler's frame marker. */ > if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp)) > - sp = current->sas_ss_sp; /* Stacks grow up! */ > + sp = (current->sas_ss_sp + 0x7f) & ~0x3f; /* Stacks grow up! */ > > DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp); > return (void __user *) sp; /* Stacks grow up. Fun. */ > > What about something like this (entirely untested, but you'll get > the idea): > > sp = round_down(current->sas_ss_sp + 64, 64); We need to round up to ensure a full 64 bytes for frame marker. I'll leave it to James to decide if it makes the code clearer. Dave -- John David Anglin dave.anglin@bell.net ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2012-11-25 22:32 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2012-11-24 15:05 sigaltstack doesn't round ss.ss_sp as required John David Anglin 2012-11-25 21:39 ` [PATCH] parisc: " John David Anglin 2012-11-25 22:07 ` Rolf Eike Beer 2012-11-25 22:32 ` John David Anglin
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