Fix a crash if a transfer outlives closing the device

Related: #1938801

1073.patch

@@ -0,0 +1,72 @@
+From bf833ee6adf58bd4a4a468aa729cdc78bdc13ede Mon Sep 17 00:00:00 2001
+From: Benjamin Berg <bberg@redhat.com>
+Date: Tue, 15 Feb 2022 11:13:41 +0100
+Subject: [PATCH 1/2] core: Catch NULL dev_handle when getting a transfer's
+ context
+
+The dev_handle will be set to NULL when the transfer is still in-flight
+while the device is closed. In that case, the transfer free function
+will try to access the context and would run into a NULL pointer
+dereference.
+
+Add a test for dev_handle being valid before dereferencing it further.
+---
+ libusb/libusbi.h | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/libusb/libusbi.h b/libusb/libusbi.h
+index 158a9af5..dde43df2 100644
+--- a/libusb/libusbi.h
++++ b/libusb/libusbi.h
+@@ -330,7 +330,7 @@ void usbi_log(struct libusb_context *ctx, enum libusb_log_level level,
+ 
+ #define DEVICE_CTX(dev)		((dev)->ctx)
+ #define HANDLE_CTX(handle)	(DEVICE_CTX((handle)->dev))
+-#define TRANSFER_CTX(transfer)	(HANDLE_CTX((transfer)->dev_handle))
++#define TRANSFER_CTX(transfer)	((transfer)->dev_handle ? HANDLE_CTX((transfer)->dev_handle) : NULL)
+ #define ITRANSFER_CTX(itransfer) \
+ 	(TRANSFER_CTX(USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer)))
+ 
+
+From 6428090ea77dfb80906a146977ea7fd6de4718c8 Mon Sep 17 00:00:00 2001
+From: Benjamin Berg <bberg@redhat.com>
+Date: Tue, 15 Feb 2022 10:59:00 +0100
+Subject: [PATCH 2/2] io: Unset dev_handle when removing transfer from flying
+ list
+
+API users might hold on to transfers a bit longer than they are in the
+flying list. If they then close the device prior to freeing all
+transfers, we would end up with invalid pointers to the device.
+
+Fix this by setting the device handle to NULL when removing the device
+from the flying list. This matches the behaviour when the device is
+closed while the transfer is still in the flying list.
+
+Specifically, the libgusb wrapper will currently only free the
+underlying transfer in a later mainloop iteration (as a side effect on
+how GTask does memory management). It is possible to fix this, but it
+would make memory management within libgusb much more error prone.
+---
+ libusb/io.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/libusb/io.c b/libusb/io.c
+index 0d2ac9ea..4e6d8984 100644
+--- a/libusb/io.c
++++ b/libusb/io.c
+@@ -1456,6 +1456,7 @@ static int add_to_flying_list(struct usbi_transfer *itransfer)
+  * if it fails to update the timer for the next timeout. */
+ static int remove_from_flying_list(struct usbi_transfer *itransfer)
+ {
++	struct libusb_transfer *transfer = USBI_TRANSFER_TO_LIBUSB_TRANSFER(itransfer);
+ 	struct libusb_context *ctx = ITRANSFER_CTX(itransfer);
+ 	int rearm_timer;
+ 	int r = 0;
+@@ -1466,6 +1467,7 @@ static int remove_from_flying_list(struct usbi_transfer *itransfer)
+ 	list_del(&itransfer->list);
+ 	if (rearm_timer)
+ 		r = arm_timer_for_next_timeout(ctx);
++	transfer->dev_handle = NULL;
+ 	usbi_mutex_unlock(&ctx->flying_transfers_lock);
+ 
+ 	return r;

libusbx.spec

@@ -1,7 +1,7 @@
 Summary:        Library for accessing USB devices
 Name:           libusbx
 Version:        1.0.25
-Release:        1%{?dist}
+Release:        2%{?dist}
 # upstream libusbx has merged back with libusb and is now called libusb again
 # but we already have a libusb package for the old libusb-compat-0.1, renaming
 # that to libusb-compat while at the same time giving this its name is a bit
@@ -17,6 +17,8 @@ Obsoletes:      libusb1 <= 1.0.9
 # Fix a crash after libusb_exit API has been misused
 # https://bugzilla.redhat.com/show_bug.cgi?id=2050638
 Patch0001:      https://github.com/libusb/libusb/pull/1058.patch
+# Fix a crash if a transfer outlives closing the device
+Patch0002:      https://github.com/libusb/libusb/pull/1073.patch
 
 # Pull in coverity related fixes
 Patch9999:      https://github.com/libusb/libusb/pull/1067.patch
@@ -126,6 +128,10 @@ LD_LIBRARY_PATH=libusb/.libs $RPM_BUILD_ROOT%{_bindir}/libusb-example-listdevs
 
 
 %changelog
+* Tue Feb 15 2022 Benjamin Berg <bberg@redhat.com> - 1.0.25-2
+- Fix a crash if a transfer outlives closing the device
+  Related: #1938801
+
 * Thu Feb 10 2022 Benjamin Berg <bberg@redhat.com> - 1.0.25-1
 - Update to 1.0.25
 - Fix a crash after libusb_exit API has been misused