From: Andy Lutomirski Date: Tue, 3 May 2016 17:31:51 +0000 (-0700) Subject: signals/sigaltstack: Report current flag bits in sigaltstack() X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=0318bc8a919ded355eaa5078689924a15c1bf52a;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git signals/sigaltstack: Report current flag bits in sigaltstack() sigaltstack()'s reported previous state uses a somewhat odd convention, but the concept of flag bits is new, and we can do the flag bits sensibly. Specifically, let's just report them directly. This will allow saving and restoring the sigaltstack state using sigaltstack() to work correctly. Signed-off-by: Andy Lutomirski Cc: Al Viro Cc: Amanieu d'Antras Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Michal Hocko Cc: Oleg Nesterov Cc: Pavel Emelyanov Cc: Peter Zijlstra (Intel) Cc: Peter Zijlstra Cc: Richard Weinberger Cc: Sasha Levin Cc: Shuah Khan Cc: Stas Sergeev Cc: Thomas Gleixner Cc: Vladimir Davydov Cc: linux-api@vger.kernel.org Link: http://lkml.kernel.org/r/94b291ec9fd47741a9264851e316e158ded0b00d.1462296606.git.luto@kernel.org Signed-off-by: Ingo Molnar --- diff --git a/kernel/signal.c b/kernel/signal.c index bf97ea5775ae..ab122a2cee41 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3099,7 +3099,8 @@ do_sigaltstack (const stack_t __user *uss, stack_t __user *uoss, unsigned long s oss.ss_sp = (void __user *) current->sas_ss_sp; oss.ss_size = current->sas_ss_size; - oss.ss_flags = sas_ss_flags(sp); + oss.ss_flags = sas_ss_flags(sp) | + (current->sas_ss_flags & SS_FLAG_BITS); if (uss) { void __user *ss_sp; diff --git a/tools/testing/selftests/sigaltstack/sas.c b/tools/testing/selftests/sigaltstack/sas.c index a98c3ef8141f..4280d0699792 100644 --- a/tools/testing/selftests/sigaltstack/sas.c +++ b/tools/testing/selftests/sigaltstack/sas.c @@ -113,6 +113,19 @@ int main(void) perror("mmap()"); return EXIT_FAILURE; } + + err = sigaltstack(NULL, &stk); + if (err) { + perror("[FAIL]\tsigaltstack()"); + exit(EXIT_FAILURE); + } + if (stk.ss_flags == SS_DISABLE) { + printf("[OK]\tInitial sigaltstack state was SS_DISABLE\n"); + } else { + printf("[FAIL]\tInitial sigaltstack state was %i; should have been SS_DISABLE\n", stk.ss_flags); + return EXIT_FAILURE; + } + stk.ss_sp = sstack; stk.ss_size = SIGSTKSZ; stk.ss_flags = SS_ONSTACK | SS_AUTODISARM; @@ -151,12 +164,12 @@ int main(void) perror("[FAIL]\tsigaltstack()"); exit(EXIT_FAILURE); } - if (stk.ss_flags != 0) { - printf("[FAIL]\tss_flags=%i, should be 0\n", + if (stk.ss_flags != SS_AUTODISARM) { + printf("[FAIL]\tss_flags=%i, should be SS_AUTODISARM\n", stk.ss_flags); exit(EXIT_FAILURE); } - printf("[OK]\tsigaltstack is enabled after signal\n"); + printf("[OK]\tsigaltstack is still SS_AUTODISARM after signal\n"); printf("[OK]\tTest passed\n"); return 0;