From 5e2dcc2c62b6603c3db85a783a09cb82af79499e Mon Sep 17 00:00:00 2001 From: Benjamin Berg Date: Tue, 22 Feb 2022 12:06:52 +0100 Subject: [PATCH] Work around API misuse in gutenprint Related: #2056326 --- ...ll-first-context-as-implicit-default.patch | 158 ++++++++++++++++++ libusb1.spec | 4 + 2 files changed, 162 insertions(+) create mode 100644 0001-core-Install-first-context-as-implicit-default.patch diff --git a/0001-core-Install-first-context-as-implicit-default.patch b/0001-core-Install-first-context-as-implicit-default.patch new file mode 100644 index 0000000..b64a29e --- /dev/null +++ b/0001-core-Install-first-context-as-implicit-default.patch @@ -0,0 +1,158 @@ +From d46cbbac4851ce6e49d8dacb0daa328453eb8a84 Mon Sep 17 00:00:00 2001 +From: Benjamin Berg +Date: Tue, 22 Feb 2022 11:45:38 +0100 +Subject: [PATCH] core: Install first context as implicit default + +There was a behaviour change in libusb, which triggers issues when the +API is misused. This caused gutenprint to crash, see +https://bugzilla.redhat.com/show_bug.cgi?id=2055504 + +For now, work around this by installing an implicit default. But, change +the code to log an error in case this "feature" is being used. +--- + libusb/core.c | 16 +++++++++++++--- + libusb/libusbi.h | 15 ++++++++++++++- + tests/umockdev.c | 31 +++++++++++++++++++++++++++++++ + 3 files changed, 58 insertions(+), 4 deletions(-) + +diff --git a/libusb/core.c b/libusb/core.c +index 1c1ada1..c75ddae 100644 +--- a/libusb/core.c ++++ b/libusb/core.c +@@ -41,6 +41,7 @@ static libusb_log_cb log_handler; + #endif + + struct libusb_context *usbi_default_context; ++struct libusb_context *usbi_fallback_context; + static int default_context_refcnt; + static usbi_mutex_static_t default_context_lock = USBI_MUTEX_INITIALIZER; + static struct usbi_option default_context_options[LIBUSB_OPTION_MAX]; +@@ -2284,7 +2285,7 @@ int API_EXPORTED libusb_init(libusb_context **ctx) + + usbi_mutex_static_lock(&default_context_lock); + +- if (!ctx && usbi_default_context) { ++ if (!ctx && default_context_refcnt > 0) { + usbi_dbg(usbi_default_context, "reusing default context"); + default_context_refcnt++; + usbi_mutex_static_unlock(&default_context_lock); +@@ -2354,9 +2355,15 @@ int API_EXPORTED libusb_init(libusb_context **ctx) + goto err_io_exit; + } + +- if (ctx) ++ if (ctx) { + *ctx = _ctx; + ++ if (!usbi_fallback_context) { ++ usbi_fallback_context = _ctx; ++ usbi_warn(usbi_fallback_context, "installing new context as implicit default"); ++ } ++ } ++ + usbi_mutex_static_unlock(&default_context_lock); + + return 0; +@@ -2429,6 +2436,8 @@ void API_EXPORTED libusb_exit(libusb_context *ctx) + + if (!ctx) + usbi_default_context = NULL; ++ if (ctx == usbi_fallback_context) ++ usbi_fallback_context = NULL; + + usbi_mutex_static_unlock(&default_context_lock); + +@@ -2575,7 +2584,8 @@ static void log_v(struct libusb_context *ctx, enum libusb_log_level level, + #else + enum libusb_log_level ctx_level; + +- ctx = usbi_get_context(ctx); ++ ctx = ctx ? ctx : usbi_default_context; ++ ctx = ctx ? ctx : usbi_fallback_context; + if (ctx) + ctx_level = ctx->debug; + else +diff --git a/libusb/libusbi.h b/libusb/libusbi.h +index 5f0d5c2..580add8 100644 +--- a/libusb/libusbi.h ++++ b/libusb/libusbi.h +@@ -436,13 +436,26 @@ struct libusb_context { + }; + + extern struct libusb_context *usbi_default_context; ++extern struct libusb_context *usbi_fallback_context; + + extern struct list_head active_contexts_list; + extern usbi_mutex_static_t active_contexts_lock; + + static inline struct libusb_context *usbi_get_context(struct libusb_context *ctx) + { +- return ctx ? ctx : usbi_default_context; ++ static int warned = 0; ++ ++ if (!ctx) { ++ ctx = usbi_default_context; ++ } ++ if (!ctx) { ++ ctx = usbi_fallback_context; ++ if (ctx && warned == 0) { ++ usbi_err(ctx, "API misuse! Using non-default context as implicit default."); ++ warned = 1; ++ } ++ } ++ return ctx; + } + + enum usbi_event_flags { +diff --git a/tests/umockdev.c b/tests/umockdev.c +index b2af512..0e73f94 100644 +--- a/tests/umockdev.c ++++ b/tests/umockdev.c +@@ -551,6 +551,32 @@ test_open_close(UMockdevTestbedFixture * fixture, UNUSED_DATA) + libusb_close(handle); + } + ++static void ++test_implicit_default(UMockdevTestbedFixture * fixture, UNUSED_DATA) ++{ ++ libusb_device **devs = NULL; ++ ++ clear_libusb_log(fixture, LIBUSB_LOG_LEVEL_INFO); ++ g_assert_cmpint(libusb_get_device_list(NULL, &devs), ==, 1); ++ libusb_free_device_list(devs, TRUE); ++ assert_libusb_log_msg(fixture, LIBUSB_LOG_LEVEL_ERROR, "\\[usbi_get_context\\].*implicit default"); ++ ++ /* Only warns once */ ++ g_assert_cmpint(libusb_get_device_list(NULL, &devs), ==, 1); ++ libusb_free_device_list(devs, TRUE); ++ clear_libusb_log(fixture, LIBUSB_LOG_LEVEL_INFO); ++ ++ libusb_init(NULL); ++ g_assert_cmpint(libusb_get_device_list(NULL, &devs), ==, 1); ++ libusb_exit(NULL); ++ ++ /* We free late, causing a warning from libusb_exit. However, ++ * we never see this warning (i.e. test success) because it is on a ++ * different context. ++ */ ++ libusb_free_device_list(devs, TRUE); ++} ++ + static void + test_close_flying(UMockdevTestbedFixture * fixture, UNUSED_DATA) + { +@@ -932,6 +958,11 @@ main(int argc, char **argv) + test_open_close, + test_fixture_teardown); + ++ g_test_add("/libusb/implicit-default", UMockdevTestbedFixture, NULL, ++ test_fixture_setup_with_canon, ++ test_implicit_default, ++ test_fixture_teardown); ++ + g_test_add("/libusb/close-flying", UMockdevTestbedFixture, NULL, + test_fixture_setup_with_canon, + test_close_flying, +-- +2.35.1 + diff --git a/libusb1.spec b/libusb1.spec index 0602138..e7c8582 100644 --- a/libusb1.spec +++ b/libusb1.spec @@ -21,6 +21,10 @@ Patch0002: https://github.com/libusb/libusb/pull/1073.patch # Add umockdev based tests from https://github.com/libusb/libusb/pull/1078 Patch0003: 0001-tests-Add-some-umockdev-based-tests.patch +# Work around API misuse in gutenprint +# https://bugzilla.redhat.com/show_bug.cgi?id=2056326 +Patch9999: 0001-core-Install-first-context-as-implicit-default.patch + %description This package provides a way for applications to access USB devices.