From: Alexey Izbyshev <izbyshev@ispras.ru>
To: musl@lists.openwall.com
Subject: [musl] [PATCH] semtimedop: fix timespec kernel ABI mismatch for 32-bit timeouts on x32
Date: Mon, 6 Mar 2023 20:56:25 +0300 [thread overview]
Message-ID: <20230306175625.219519-1-izbyshev@ispras.ru> (raw)
For time64 support, musl normally defines SYS_foo to the time32 variant
of that syscall on arches that have it, and to the time64 variant
otherwise, so that "SYS_foo == SYS_foo_time64" implies that the arch is
time64-only. However, SYS_semtimedop is an odd case: some arches define
only SYS_semtimedop_time64, yet they are not time64-only, because the
time32 variant is provided via SYS_ipc instead. For such arches,
defining SYS_semtimedop to SYS_semtimedop_time64 would break the
implication above, so commit 4bbd7baea7c8538b3fb8e30f7b022a1eee071450
doesn't do this. Commit eb2e298cdc814493a6ced8c05cf0d0f5cccc8b63
attempts to detect time64-only arches by checking that both
SYS_semtimedop and SYS_ipc are undefined, but this doesn't work for
x32, because it's a time64-only arch that does define SYS_semtimedop.
As a result, 32-bit timeouts trigger the fallback path that passes
a 32-bit timespec to the kernel while it expects a 64-bit one, so
the effective tv_sec is formed by interpreting 32-bit tv_sec and
tv_nsec as a single long long, and the effective tv_nsec is whatever
is located in the next 64 bits of the stack.
Fix this by expanding the time64-only check to include arches where
SYS_semtimedop is the time64 variant of the syscall.
---
src/ipc/semtimedop.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/src/ipc/semtimedop.c b/src/ipc/semtimedop.c
index 1632e7b0..a104af21 100644
--- a/src/ipc/semtimedop.c
+++ b/src/ipc/semtimedop.c
@@ -7,7 +7,8 @@
#define IS32BIT(x) !((x)+0x80000000ULL>>32)
#define CLAMP(x) (int)(IS32BIT(x) ? (x) : 0x7fffffffU+((0ULL+(x))>>63))
-#if !defined(SYS_semtimedop) && !defined(SYS_ipc)
+#if !defined(SYS_semtimedop) && !defined(SYS_ipc) || \
+ SYS_semtimedop == SYS_semtimedop_time64
#define NO_TIME32 1
#else
#define NO_TIME32 0
--
2.39.1
next reply other threads:[~2023-03-06 17:56 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-06 17:56 Alexey Izbyshev [this message]
2023-04-11 13:23 ` Rich Felker
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20230306175625.219519-1-izbyshev@ispras.ru \
--to=izbyshev@ispras.ru \
--cc=musl@lists.openwall.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.vuxu.org/mirror/musl/
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).