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linux-user: Block signals during sigaction() handling 

Block signals while emulating sigaction. This is a non-interruptible
syscall, and using block_signals() avoids races where the host
signal handler is invoked and tries to examine the signal handler
data structures while we are updating them.

Signed-off-by: Timothy Edward Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
Message-id: 1441497448-32489-29-git-send-email-T.E.Baldwin99@members.leeds.ac.uk
[PMM: expanded commit message]
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
This commit is contained in:
Timothy E Baldwin 2016-05-27 15:51:54 +01:00 committed by Riku Voipio
parent 655ed67c2a
commit ef6a778ea2
1 changed files with 9 additions and 3 deletions
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12
linux-user/signal.c
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@ -640,7 +640,7 @@ out:
return ret; return ret;
} }
/* do_sigaction() return host values and errnos */ /* do_sigaction() return target values and host errnos */
int do_sigaction(int sig, const struct target_sigaction *act, int do_sigaction(int sig, const struct target_sigaction *act,
struct target_sigaction *oact) struct target_sigaction *oact)
{ {
@ -649,8 +649,14 @@ int do_sigaction(int sig, const struct target_sigaction *act,
int host_sig; int host_sig;
int ret = 0; int ret = 0;
if (sig < 1 || sig > TARGET_NSIG || sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) if (sig < 1 || sig > TARGET_NSIG || sig == TARGET_SIGKILL || sig == TARGET_SIGSTOP) {
return -EINVAL; return -TARGET_EINVAL;
}
if (block_signals()) {
return -TARGET_ERESTARTSYS;
}
k = &sigact_table[sig - 1]; k = &sigact_table[sig - 1];
if (oact) { if (oact) {
__put_user(k->_sa_handler, &oact->_sa_handler); __put_user(k->_sa_handler, &oact->_sa_handler);