aboutsummaryrefslogtreecommitdiff
path: root/hurd
diff options
context:
space:
mode:
authorSergey Bugaev <bugaevc@gmail.com>2023-03-19 18:10:08 +0300
committerSamuel Thibault <samuel.thibault@ens-lyon.org>2023-04-10 23:54:28 +0200
commit747812349d42427c835aeac987aa67641d84f1ad (patch)
treee9391fe71f0f029218155bb38bac64838b8df7fb /hurd
parentb37899d34d2190ef4b454283188f22519f096048 (diff)
downloadglibc-747812349d42427c835aeac987aa67641d84f1ad.zip
glibc-747812349d42427c835aeac987aa67641d84f1ad.tar.gz
glibc-747812349d42427c835aeac987aa67641d84f1ad.tar.bz2
hurd: Improve reply port handling when exiting signal handlers
If we're doing signals, that means we've already got the signal thread running, and that implies TLS having been set up. So we know that __hurd_local_reply_port will resolve to THREAD_SELF->reply_port, and can access that directly using the THREAD_GETMEM and THREAD_SETMEM macros. This avoids potential miscompilations, and should also be a tiny bit faster. Also, use mach_port_mod_refs () and not mach_port_destroy () to destroy the receive right. mach_port_destroy () should *never* be used on mach_task_self (); this can easily lead to port use-after-free vulnerabilities if the task has any other references to the same port. Signed-off-by: Sergey Bugaev <bugaevc@gmail.com> Message-Id: <20230319151017.531737-26-bugaevc@gmail.com>
Diffstat (limited to 'hurd')
-rw-r--r--hurd/sigunwind.c24
1 files changed, 11 insertions, 13 deletions
diff --git a/hurd/sigunwind.c b/hurd/sigunwind.c
index edd40b1..399e690 100644
--- a/hurd/sigunwind.c
+++ b/hurd/sigunwind.c
@@ -18,7 +18,6 @@
#include <hurd.h>
#include <thread_state.h>
-#include <hurd/threadvar.h>
#include <jmpbuf-unwind.h>
#include <assert.h>
#include <stdint.h>
@@ -39,19 +38,18 @@ _hurdsig_longjmp_from_handler (void *data, jmp_buf env, int val)
{
/* Destroy the MiG reply port used by the signal handler, and restore
the reply port in use by the thread when interrupted. */
- mach_port_t *reply_port = &__hurd_local_reply_port;
- if (*reply_port)
- {
- mach_port_t port = *reply_port;
- /* Assigning MACH_PORT_DEAD here tells libc's mig_get_reply_port
- not to get another reply port, but avoids mig_dealloc_reply_port
- trying to deallocate it after the receive fails (which it will,
- because the reply port will be bogus, regardless). */
- *reply_port = MACH_PORT_DEAD;
- __mach_port_destroy (__mach_task_self (), port);
- }
+ mach_port_t reply_port = THREAD_GETMEM (THREAD_SELF, reply_port);
+ /* Assigning MACH_PORT_DEAD here tells libc's mig_get_reply_port not to
+ get another reply port, but avoids mig_dealloc_reply_port trying to
+ deallocate it after the receive fails (which it will, because the
+ reply port will be bogus, regardless). */
+ THREAD_SETMEM (THREAD_SELF, reply_port, MACH_PORT_DEAD);
+ if (MACH_PORT_VALID (reply_port))
+ __mach_port_mod_refs (__mach_task_self (), reply_port,
+ MACH_PORT_RIGHT_RECEIVE, -1);
if (scp->sc_reply_port)
- __mach_port_destroy (__mach_task_self (), scp->sc_reply_port);
+ __mach_port_mod_refs (__mach_task_self (), scp->sc_reply_port,
+ MACH_PORT_RIGHT_RECEIVE, -1);
}
__spin_lock (&ss->lock);