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x86: signal: check sas_ss_size instead of sas_ss_flags() 

Impact: fix redundant and incorrect check

Oleg Nesterov noticed wrt commit:

  14fc9fb: x86: signal: check signal stack overflow properly

>> No need to check SA_ONSTACK if we're already using alternate signal stack.
>
> Yes, but this also mean that we don't need sas_ss_flags() under
> "if (!onsigstack)",

Checking on_sig_stack() in sas_ss_flags() at get_sigframe() is redundant
and not correct on 64 bit. To check sas_ss_size is enough.

Reported-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Cc: roland@redhat.com
LKML-Reference: <49CBB54C.5080201@ct.jp.nec.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This commit is contained in:
Hiroshi Shimamoto 2009-03-26 10:03:08 -07:00 committed by Ingo Molnar
parent 93394a761d
commit 0f8f308925
1 changed files with 1 additions and 1 deletions
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2
arch/x86/kernel/signal.c
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@ -221,7 +221,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size,
if (!onsigstack) {
/* This is the X/Open sanctioned signal stack switching. */
if (ka->sa.sa_flags & SA_ONSTACK) {
if (sas_ss_flags(sp) == 0)
if (current->sas_ss_size)
sp = current->sas_ss_sp + current->sas_ss_size;
} else {
#ifdef CONFIG_X86_32