[hurd,commited] hurd: Fix using altstack while in an RPC call to be aborted
Samuel Thibault
samuel.thibault@ens-lyon.org
Fri Dec 13 02:25:00 GMT 2019
* sysdeps/mach/hurd/i386/trampoline.c (_hurd_setup_sighandler): Always check
for interrupted code being with esp pointing at mach_msg arguments, even
when using an altstack. If we need to abort the RPC we will need
this.
---
sysdeps/mach/hurd/i386/trampoline.c | 27 ++++++++++++++-------------
1 file changed, 14 insertions(+), 13 deletions(-)
diff --git a/sysdeps/mach/hurd/i386/trampoline.c b/sysdeps/mach/hurd/i386/trampoline.c
index a6928a607b..0c5d5a194c 100644
--- a/sysdeps/mach/hurd/i386/trampoline.c
+++ b/sysdeps/mach/hurd/i386/trampoline.c
@@ -74,12 +74,6 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler,
interrupted RPC frame. */
state->basic.esp = state->basic.uesp;
- if ((ss->actions[signo].sa_flags & SA_ONSTACK)
- && !(ss->sigaltstack.ss_flags & (SS_DISABLE|SS_ONSTACK)))
- {
- sigsp = ss->sigaltstack.ss_sp + ss->sigaltstack.ss_size;
- ss->sigaltstack.ss_flags |= SS_ONSTACK;
- }
/* This code has intimate knowledge of the special mach_msg system call
done in intr-msg.c; that code does (see intr-msg.h):
movl %esp, %ecx
@@ -91,13 +85,20 @@ _hurd_setup_sighandler (struct hurd_sigstate *ss, __sighandler_t handler,
We must check for the window during which %esp points at the
mach_msg arguments. The space below until %ecx is used by
the _hurd_intr_rpc_mach_msg frame, and must not be clobbered. */
- else if (state->basic.eip >= (int) &_hurd_intr_rpc_msg_cx_sp
- && state->basic.eip < (int) &_hurd_intr_rpc_msg_sp_restored)
- /* The SP now points at the mach_msg args, but there is more stack
- space used below it. The real SP is saved in %ecx; we must push the
- new frame below there, and restore that value as the SP on
- sigreturn. */
- sigsp = (char *) (state->basic.uesp = state->basic.ecx);
+ if (state->basic.eip >= (int) &_hurd_intr_rpc_msg_cx_sp
+ && state->basic.eip < (int) &_hurd_intr_rpc_msg_sp_restored)
+ /* The SP now points at the mach_msg args, but there is more stack
+ space used below it. The real SP is saved in %ecx; we must push the
+ new frame below there (if not on the altstack), and restore that value as
+ the SP on sigreturn. */
+ state->basic.uesp = state->basic.ecx;
+
+ if ((ss->actions[signo].sa_flags & SA_ONSTACK)
+ && !(ss->sigaltstack.ss_flags & (SS_DISABLE|SS_ONSTACK)))
+ {
+ sigsp = ss->sigaltstack.ss_sp + ss->sigaltstack.ss_size;
+ ss->sigaltstack.ss_flags |= SS_ONSTACK;
+ }
else
sigsp = (char *) state->basic.uesp;
--
2.24.0
More information about the Libc-alpha
mailing list