AuroraMiddleware/glibc
1
0
Fork 0
mirror of https://sourceware.org/git/glibc.git synced 2024-11-21 12:30:06 +00:00
Code Issues Packages Projects Releases Wiki Activity

hurd: Replace reply port with a dead name on failed interruption

Browse Source 
If we're trying to interrupt an interruptible RPC, but the server fails
to respond to our __interrupt_operation () call, we instead destroy the
reply port we were expecting the reply to the RPC on.

Instead of deallocating the name completely, replace it with a dead
name, so the name won't get reused for some other right, and deallocate
it in _hurd_intr_rpc_mach_msg once we return from the signal handler.

Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
Message-Id: <20230429201822.2605207-4-bugaevc@gmail.com>
This commit is contained in:
Sergey Bugaev 2023-04-29 23:18:19 +03:00 committed by Samuel Thibault
parent eb14819c14
commit 4e506f67cb
3 changed files with 20 additions and 21 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
hurd/hurdsig.c
View File

@ -477,9 +477,18 @@ _hurdsig_abort_rpcs (struct hurd_sigstate *ss, int signo, int sigthread,
if (reply)
{
/* The interrupt didn't work.
Destroy the receive right the thread is blocked on. */
__mach_port_destroy (__mach_task_self (), *reply);
*reply = MACH_PORT_NULL;
Destroy the receive right the thread is blocked on, and
replace it with a dead name to keep the name from reuse until
the therad is done with it. To do this atomically, first
insert a send right, and then destroy the receive right,
turning the send right into a dead name. */
err = __mach_port_insert_right (__mach_task_self (),
*reply, *reply,
MACH_MSG_TYPE_MAKE_SEND);
assert_perror (err);
err = __mach_port_mod_refs (__mach_task_self (), *reply,
MACH_PORT_RIGHT_RECEIVE, -1);
assert_perror (err);
}
/* The system call return value register now contains

1
hurd/intr-msg.c
View File

@ -305,6 +305,7 @@ _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
{
/* Make sure we have a valid reply port. The one we were using
may have been destroyed by interruption. */
__mig_dealloc_reply_port (rcv_name);
m->header.msgh_local_port = rcv_name = __mig_get_reply_port ();
m->header.msgh_bits = msgh_bits;
option = user_option;

25
sysdeps/mach/hurd/mig-reply.c
View File

@ -69,29 +69,18 @@ __mig_dealloc_reply_port (mach_port_t arg)
mach_port_t port = get_reply_port ();
set_reply_port (MACH_PORT_NULL); /* So the mod_refs RPC won't use it. */
/* Normally, ARG should be the same as PORT that we store. However, if a
signal has interrupted the RPC, the stored PORT has been deallocated and
reset to MACH_PORT_NULL (or possibly MACH_PORT_DEAD). In this case the
MIG routine still has the old name, which it passes to us here. We must
not deallocate (or otherwise touch) it, since it may be already allocated
to another port right. Fortunately MIG itself doesn't do anything with
the reply port on errors either, other than immediately calling this
function.
And so:
1. Assert that things are sane, i.e. and PORT is either invalid or same
as ARG.
2. Only deallocate the name if our stored PORT still names it. In that
case we're sure the right has not been deallocated / the name reused.
*/
assert (port == arg);
if (!MACH_PORT_VALID (port))
return;
assert (port == arg);
err = __mach_port_mod_refs (__mach_task_self (), port,
MACH_PORT_RIGHT_RECEIVE, -1);
if (err == KERN_INVALID_RIGHT)
/* It could be that during signal handling, the receive right had been
replaced with a dead name. */
err = __mach_port_mod_refs (__mach_task_self (), port,
MACH_PORT_RIGHT_DEAD_NAME, -1);
assert_perror (err);
}
weak_alias (__mig_dealloc_reply_port, mig_dealloc_reply_port)