set_cloexec() had a bit too much copy&pate from setnonblock(), and
insufficient testing on ancient versions of Linux...
As written (emulating ancient linux by undef'ing O_CLOEXEC), strace shows:
open("/dev/xen/xenbus", O_RDWR) = 3
fcntl(3, F_GETFL) = 0x8002 (flags O_RDWR|O_LARGEFILE)
fcntl(3, 0x8003 /* F_??? */, 0x7ffe4a771d90) = -1 EINVAL (Invalid argument)
close(3) = 0
which is obviously nonsense.
Switch F_GETFL -> F_GETFD, and fix the second invocation to use F_SETFD. With
this, strace is rather happer:
open("/dev/xen/xenbus", O_RDWR) = 3
fcntl(3, F_GETFD) = 0
fcntl(3, F_SETFD, FD_CLOEXEC) = 0
Fixes: bf7c1464706a ("tools/libxs: Fix CLOEXEC handling in get_dev()")
Reported-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: Anthony PERARD <anthony.perard@vates.tech>
CC: Juergen Gross <jgross@suse.com>
CC: Ross Lagerwall <ross.lagerwall@citrix.com>
CC: Oleksii Kurochko <oleksii.kurochko@gmail.com>
CC: Jan Beulich <JBeulich@suse.com>
I'm embarassed to say that this was only spotted by Ross when I was
cherrypicking fixes from staging-4.17 into the XenServer patchqueue.
This is urgent to take for 4.19, and to backport into 4.17/18 seeing as the
breakage has been backported already.
---
tools/libs/store/xs.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/libs/store/xs.c b/tools/libs/store/xs.c
index c8845b69e284..38a6ce3cf2ea 100644
--- a/tools/libs/store/xs.c
+++ b/tools/libs/store/xs.c
@@ -182,12 +182,12 @@ static bool setnonblock(int fd, int nonblock) {
static bool set_cloexec(int fd)
{
- int flags = fcntl(fd, F_GETFL);
+ int flags = fcntl(fd, F_GETFD);
if (flags < 0)
return false;
- return fcntl(fd, flags | FD_CLOEXEC) >= 0;
+ return fcntl(fd, F_SETFD, flags | FD_CLOEXEC) >= 0;
}
static int pipe_cloexec(int fds[2])
--
2.39.2
On 08.07.24 17:15, Andrew Cooper wrote: > set_cloexec() had a bit too much copy&pate from setnonblock(), and > insufficient testing on ancient versions of Linux... > > As written (emulating ancient linux by undef'ing O_CLOEXEC), strace shows: > > open("/dev/xen/xenbus", O_RDWR) = 3 > fcntl(3, F_GETFL) = 0x8002 (flags O_RDWR|O_LARGEFILE) > fcntl(3, 0x8003 /* F_??? */, 0x7ffe4a771d90) = -1 EINVAL (Invalid argument) > close(3) = 0 > > which is obviously nonsense. > > Switch F_GETFL -> F_GETFD, and fix the second invocation to use F_SETFD. With > this, strace is rather happer: > > open("/dev/xen/xenbus", O_RDWR) = 3 > fcntl(3, F_GETFD) = 0 > fcntl(3, F_SETFD, FD_CLOEXEC) = 0 > > Fixes: bf7c1464706a ("tools/libxs: Fix CLOEXEC handling in get_dev()") > Reported-by: Ross Lagerwall <ross.lagerwall@citrix.com> > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Juergen Gross <jgross@suse.com> Juergen
On Mon, Jul 8, 2024 at 4:15 PM Andrew Cooper <andrew.cooper3@citrix.com> wrote: > > set_cloexec() had a bit too much copy&pate from setnonblock(), and > insufficient testing on ancient versions of Linux... > > As written (emulating ancient linux by undef'ing O_CLOEXEC), strace shows: > > open("/dev/xen/xenbus", O_RDWR) = 3 > fcntl(3, F_GETFL) = 0x8002 (flags O_RDWR|O_LARGEFILE) > fcntl(3, 0x8003 /* F_??? */, 0x7ffe4a771d90) = -1 EINVAL (Invalid argument) > close(3) = 0 > > which is obviously nonsense. > > Switch F_GETFL -> F_GETFD, and fix the second invocation to use F_SETFD. With > this, strace is rather happer: > > open("/dev/xen/xenbus", O_RDWR) = 3 > fcntl(3, F_GETFD) = 0 > fcntl(3, F_SETFD, FD_CLOEXEC) = 0 > > Fixes: bf7c1464706a ("tools/libxs: Fix CLOEXEC handling in get_dev()") > Reported-by: Ross Lagerwall <ross.lagerwall@citrix.com> > Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com> Thanks
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