diff options
Diffstat (limited to '0018-tools-ocaml-evtchn-Don-t-reference-Custom-objects-wi.patch')
| -rw-r--r-- | 0018-tools-ocaml-evtchn-Don-t-reference-Custom-objects-wi.patch | 213 |
1 files changed, 213 insertions, 0 deletions
diff --git a/0018-tools-ocaml-evtchn-Don-t-reference-Custom-objects-wi.patch b/0018-tools-ocaml-evtchn-Don-t-reference-Custom-objects-wi.patch new file mode 100644 index 0000000..8e1c860 --- /dev/null +++ b/0018-tools-ocaml-evtchn-Don-t-reference-Custom-objects-wi.patch @@ -0,0 +1,213 @@ +From e18faeb91e620624106b94c8821f8c9574eddb17 Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Edwin=20T=C3=B6r=C3=B6k?= <edwin.torok@cloud.com> +Date: Thu, 12 Jan 2023 17:48:29 +0000 +Subject: [PATCH 18/61] tools/ocaml/evtchn: Don't reference Custom objects with + the GC lock released +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +The modification to the _H() macro for Ocaml 5 support introduced a subtle +bug. From the manual: + + https://ocaml.org/manual/intfc.html#ss:parallel-execution-long-running-c-code + +"After caml_release_runtime_system() was called and until +caml_acquire_runtime_system() is called, the C code must not access any OCaml +data, nor call any function of the run-time system, nor call back into OCaml +code." + +Previously, the value was a naked C pointer, so dereferencing it wasn't +"accessing any Ocaml data", but the fix to avoid naked C pointers added a +layer of indirection through an Ocaml Custom object, meaning that the common +pattern of using _H() in a blocking section is unsafe. + +In order to fix: + + * Drop the _H() macro and replace it with a static inline xce_of_val(). + * Opencode the assignment into Data_custom_val() in the two constructors. + * Rename "value xce" parameters to "value xce_val" so we can consistently + have "xenevtchn_handle *xce" on the stack, and obtain the pointer with the + GC lock still held. + +Fixes: 22d5affdf0ce ("tools/ocaml/evtchn: OCaml 5 support, fix potential resource leak") +Signed-off-by: Edwin Török <edwin.torok@cloud.com> +Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com> +Acked-by: Christian Lindig <christian.lindig@citrix.com> +(cherry picked from commit 2636d8ff7a670c4d2485757dbe966e36c259a960) +--- + tools/ocaml/libs/eventchn/xeneventchn_stubs.c | 60 +++++++++++-------- + 1 file changed, 35 insertions(+), 25 deletions(-) + +diff --git a/tools/ocaml/libs/eventchn/xeneventchn_stubs.c b/tools/ocaml/libs/eventchn/xeneventchn_stubs.c +index aa8a69cc1e..d7881ca95f 100644 +--- a/tools/ocaml/libs/eventchn/xeneventchn_stubs.c ++++ b/tools/ocaml/libs/eventchn/xeneventchn_stubs.c +@@ -33,11 +33,14 @@ + #include <caml/fail.h> + #include <caml/signals.h> + +-#define _H(__h) (*((xenevtchn_handle **)Data_custom_val(__h))) ++static inline xenevtchn_handle *xce_of_val(value v) ++{ ++ return *(xenevtchn_handle **)Data_custom_val(v); ++} + + static void stub_evtchn_finalize(value v) + { +- xenevtchn_close(_H(v)); ++ xenevtchn_close(xce_of_val(v)); + } + + static struct custom_operations xenevtchn_ops = { +@@ -68,7 +71,7 @@ CAMLprim value stub_eventchn_init(value cloexec) + caml_failwith("open failed"); + + result = caml_alloc_custom(&xenevtchn_ops, sizeof(xce), 0, 1); +- _H(result) = xce; ++ *(xenevtchn_handle **)Data_custom_val(result) = xce; + + CAMLreturn(result); + } +@@ -87,18 +90,19 @@ CAMLprim value stub_eventchn_fdopen(value fdval) + caml_failwith("evtchn fdopen failed"); + + result = caml_alloc_custom(&xenevtchn_ops, sizeof(xce), 0, 1); +- _H(result) = xce; ++ *(xenevtchn_handle **)Data_custom_val(result) = xce; + + CAMLreturn(result); + } + +-CAMLprim value stub_eventchn_fd(value xce) ++CAMLprim value stub_eventchn_fd(value xce_val) + { +- CAMLparam1(xce); ++ CAMLparam1(xce_val); + CAMLlocal1(result); ++ xenevtchn_handle *xce = xce_of_val(xce_val); + int fd; + +- fd = xenevtchn_fd(_H(xce)); ++ fd = xenevtchn_fd(xce); + if (fd == -1) + caml_failwith("evtchn fd failed"); + +@@ -107,13 +111,14 @@ CAMLprim value stub_eventchn_fd(value xce) + CAMLreturn(result); + } + +-CAMLprim value stub_eventchn_notify(value xce, value port) ++CAMLprim value stub_eventchn_notify(value xce_val, value port) + { +- CAMLparam2(xce, port); ++ CAMLparam2(xce_val, port); ++ xenevtchn_handle *xce = xce_of_val(xce_val); + int rc; + + caml_enter_blocking_section(); +- rc = xenevtchn_notify(_H(xce), Int_val(port)); ++ rc = xenevtchn_notify(xce, Int_val(port)); + caml_leave_blocking_section(); + + if (rc == -1) +@@ -122,15 +127,16 @@ CAMLprim value stub_eventchn_notify(value xce, value port) + CAMLreturn(Val_unit); + } + +-CAMLprim value stub_eventchn_bind_interdomain(value xce, value domid, ++CAMLprim value stub_eventchn_bind_interdomain(value xce_val, value domid, + value remote_port) + { +- CAMLparam3(xce, domid, remote_port); ++ CAMLparam3(xce_val, domid, remote_port); + CAMLlocal1(port); ++ xenevtchn_handle *xce = xce_of_val(xce_val); + xenevtchn_port_or_error_t rc; + + caml_enter_blocking_section(); +- rc = xenevtchn_bind_interdomain(_H(xce), Int_val(domid), Int_val(remote_port)); ++ rc = xenevtchn_bind_interdomain(xce, Int_val(domid), Int_val(remote_port)); + caml_leave_blocking_section(); + + if (rc == -1) +@@ -140,14 +146,15 @@ CAMLprim value stub_eventchn_bind_interdomain(value xce, value domid, + CAMLreturn(port); + } + +-CAMLprim value stub_eventchn_bind_virq(value xce, value virq_type) ++CAMLprim value stub_eventchn_bind_virq(value xce_val, value virq_type) + { +- CAMLparam2(xce, virq_type); ++ CAMLparam2(xce_val, virq_type); + CAMLlocal1(port); ++ xenevtchn_handle *xce = xce_of_val(xce_val); + xenevtchn_port_or_error_t rc; + + caml_enter_blocking_section(); +- rc = xenevtchn_bind_virq(_H(xce), Int_val(virq_type)); ++ rc = xenevtchn_bind_virq(xce, Int_val(virq_type)); + caml_leave_blocking_section(); + + if (rc == -1) +@@ -157,13 +164,14 @@ CAMLprim value stub_eventchn_bind_virq(value xce, value virq_type) + CAMLreturn(port); + } + +-CAMLprim value stub_eventchn_unbind(value xce, value port) ++CAMLprim value stub_eventchn_unbind(value xce_val, value port) + { +- CAMLparam2(xce, port); ++ CAMLparam2(xce_val, port); ++ xenevtchn_handle *xce = xce_of_val(xce_val); + int rc; + + caml_enter_blocking_section(); +- rc = xenevtchn_unbind(_H(xce), Int_val(port)); ++ rc = xenevtchn_unbind(xce, Int_val(port)); + caml_leave_blocking_section(); + + if (rc == -1) +@@ -172,14 +180,15 @@ CAMLprim value stub_eventchn_unbind(value xce, value port) + CAMLreturn(Val_unit); + } + +-CAMLprim value stub_eventchn_pending(value xce) ++CAMLprim value stub_eventchn_pending(value xce_val) + { +- CAMLparam1(xce); ++ CAMLparam1(xce_val); + CAMLlocal1(result); ++ xenevtchn_handle *xce = xce_of_val(xce_val); + xenevtchn_port_or_error_t port; + + caml_enter_blocking_section(); +- port = xenevtchn_pending(_H(xce)); ++ port = xenevtchn_pending(xce); + caml_leave_blocking_section(); + + if (port == -1) +@@ -189,16 +198,17 @@ CAMLprim value stub_eventchn_pending(value xce) + CAMLreturn(result); + } + +-CAMLprim value stub_eventchn_unmask(value xce, value _port) ++CAMLprim value stub_eventchn_unmask(value xce_val, value _port) + { +- CAMLparam2(xce, _port); ++ CAMLparam2(xce_val, _port); ++ xenevtchn_handle *xce = xce_of_val(xce_val); + evtchn_port_t port; + int rc; + + port = Int_val(_port); + + caml_enter_blocking_section(); +- rc = xenevtchn_unmask(_H(xce), port); ++ rc = xenevtchn_unmask(xce, port); + caml_leave_blocking_section(); + + if (rc) +-- +2.40.0 + |