From: James Y Knight <jyknight@google.com>
To: musl@lists.openwall.com
Subject: [PATCH] Fix the use of sigaltstack to return to the saved main stack.
Date: Tue, 9 Jul 2019 15:01:50 -0400 [thread overview]
Message-ID: <CAA2zVHpSiKgq8tBpjy5Zjbb1UtoJ++UtT8EvFDJqFmb+mtDLBQ@mail.gmail.com> (raw)
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Previously, musl would reject the call, because the main stack has
ss_size == 0 and ss_flags == SS_DISABLE.
We could condition on ss_flags not containing SS_DISABLE, but instead,
simply remove the ss_size check, as the kernel performs the same check,
anyhow.
[[Note: I've also included the corresponding patch to libc-tests. I'm not
sure if this is OK, or if I should send it separately?]]
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[-- Attachment #2: 0001-Fix-the-use-of-sigaltstack-to-return-to-the-saved-ma.patch --]
[-- Type: text/x-patch, Size: 1162 bytes --]
From fe70a508fe945cb1a44f8a6bbd87ee295637447b Mon Sep 17 00:00:00 2001
From: James Y Knight <jyknight@google.com>
Date: Tue, 9 Jul 2019 14:59:01 -0400
Subject: [PATCH] Fix the use of sigaltstack to return to the saved main stack.
Previously, musl would reject the call, because the main stack has
ss_size == 0 and ss_flags == SS_DISABLE.
We could condition on ss_flags not containing SS_DISABLE, but instead,
simply remove the ss_size check, as the kernel performs the same check,
anyhow.
---
src/signal/sigaltstack.c | 12 +++---------
1 file changed, 3 insertions(+), 9 deletions(-)
diff --git a/src/signal/sigaltstack.c b/src/signal/sigaltstack.c
index cfa3f5c1..d8e8eb0b 100644
--- a/src/signal/sigaltstack.c
+++ b/src/signal/sigaltstack.c
@@ -4,15 +4,9 @@
int sigaltstack(const stack_t *restrict ss, stack_t *restrict old)
{
- if (ss) {
- if (ss->ss_size < MINSIGSTKSZ) {
- errno = ENOMEM;
- return -1;
- }
- if (ss->ss_flags & SS_ONSTACK) {
- errno = EINVAL;
- return -1;
- }
+ if (ss && (ss->ss_flags & SS_ONSTACK)) {
+ errno = EINVAL;
+ return -1;
}
return syscall(SYS_sigaltstack, ss, old);
}
--
2.22.0.410.gd8fdbe21b5-goog
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[-- Type: text/x-patch, Size: 1165 bytes --]
From 9272ed8666f930dc2f24d05b1fd248584bbf495f Mon Sep 17 00:00:00 2001
From: James Y Knight <jyknight@google.com>
Date: Tue, 9 Jul 2019 14:31:24 -0400
Subject: [PATCH] Verify that returning to the original stack doesn't return an
error (e.g. ENOMEM).
---
src/regression/sigaltstack.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/regression/sigaltstack.c b/src/regression/sigaltstack.c
index bfdc44a..6847454 100644
--- a/src/regression/sigaltstack.c
+++ b/src/regression/sigaltstack.c
@@ -30,7 +30,7 @@ static void handler(int sig)
int main(void)
{
- stack_t ss;
+ stack_t ss, oldss;
struct sigaction sa;
ss.ss_sp = stack;
@@ -39,7 +39,7 @@ int main(void)
sa.sa_handler = handler;
sa.sa_flags = SA_ONSTACK;
- T(sigaltstack(&ss, 0));
+ T(sigaltstack(&ss, &oldss));
T(sigfillset(&sa.sa_mask));
T(sigaction(SIGUSR1, &sa, 0));
T(raise(SIGUSR1));
@@ -56,7 +56,7 @@ int main(void)
t_error("sigaltstack with bad ss_flags should have failed with EINVAL, "
"got %s\n", strerror(errno));
errno = 0;
- T(sigaltstack(0, 0));
+ T(sigaltstack(oldss, 0));
return t_status;
}
--
2.22.0.410.gd8fdbe21b5-goog
next reply other threads:[~2019-07-09 19:01 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-09 19:01 James Y Knight [this message]
2019-07-09 19:30 ` Rich Felker
2019-07-10 18:04 ` James Y Knight
2019-07-10 18:39 ` Rich Felker
2019-07-10 20:11 ` James Y Knight
2019-07-10 21:23 ` Szabolcs Nagy
2019-07-10 21:48 ` Rich Felker
2019-07-11 15:51 ` James Y Knight
2019-07-12 9:18 ` Florian Weimer
2019-07-12 16:06 ` Rich Felker
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