From 4310c6b8e75d6a47f7548e5948fbe6318aa4440a Mon Sep 17 00:00:00 2001 From: Fedor Pchelkin Date: Mon, 31 Aug 2026 10:58:09 +0300 Subject: thunderbolt: Fix NULL dereference in tb_remove_work() There is a slight race between tb_remove_work() and tb_domain_remove() which leads to dereferencing a NULL tb->root_switch pointer inside tb_free_unplugged_xdomains(): Thread A Thread B tb_remove_work() tb_domain_remove() mutex_lock(&tb->lock) tb_stop() /* doesn't cancel a running callback */ cancel_delayed_work(&tcm->remove_work) ... tb_switch_remove(tb->root_switch) tb->root_switch = NULL mutex_unlock(&tb->lock) mutex_lock(&tb->lock) ... /* without checking ->root_switch */ tb_free_unplugged_xdomains(tb->root_switch) mutex_unlock(&tb->lock) Commit a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") doesn't seem right to move tb_free_unplugged_xdomains() out of the &tb->lock section and the check for tb->root_switch, in particular. It states: For this reason separate removing the XDomain from the topology data structures (where we need the lock) from unregistering the device from the bus (where remove callbacks of the drivers are being called). tb_free_unplugged_xdomains() belongs to the former group of functions requiring the lock. And it also calls tb_xdomain_remove() which should only be called with &tb->lock held. Found by Linux Verification Center (linuxtesting.org) with Svace static analysis tool. Fixes: a8937f35cf39 ("thunderbolt: Remove XDomain from the bus without holding tb->lock") Cc: stable@vger.kernel.org Signed-off-by: Fedor Pchelkin Signed-off-by: Mika Westerberg --- lib/test_dynamic_debug.c | 166 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 166 insertions(+) create mode 100644 lib/test_dynamic_debug.c (limited to 'lib/test_dynamic_debug.c') diff --git a/lib/test_dynamic_debug.c b/lib/test_dynamic_debug.c new file mode 100644 index 000000000..77c2a669b --- /dev/null +++ b/lib/test_dynamic_debug.c @@ -0,0 +1,166 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Kernel module for testing dynamic_debug + * + * Authors: + * Jim Cromie + */ + +#define pr_fmt(fmt) "test_dd: " fmt + +#include + +/* run tests by reading or writing sysfs node: do_prints */ + +static void do_prints(void); /* device under test */ +static int param_set_do_prints(const char *instr, const struct kernel_param *kp) +{ + do_prints(); + return 0; +} +static int param_get_do_prints(char *buffer, const struct kernel_param *kp) +{ + do_prints(); + return scnprintf(buffer, PAGE_SIZE, "did do_prints\n"); +} +static const struct kernel_param_ops param_ops_do_prints = { + .set = param_set_do_prints, + .get = param_get_do_prints, +}; +module_param_cb(do_prints, ¶m_ops_do_prints, NULL, 0600); + +/* + * Using the CLASSMAP api: + * - classmaps must have corresponding enum + * - enum symbols must match/correlate with class-name strings in the map. + * - base must equal enum's 1st value + * - multiple maps must set their base to share the 0-30 class_id space !! + * (build-bug-on tips welcome) + * Additionally, here: + * - tie together sysname, mapname, bitsname, flagsname + */ +#define DD_SYS_WRAP(_model, _flags) \ + static unsigned long bits_##_model; \ + static struct ddebug_class_param _flags##_model = { \ + .bits = &bits_##_model, \ + .flags = #_flags, \ + .map = &map_##_model, \ + }; \ + module_param_cb(_flags##_##_model, ¶m_ops_dyndbg_classes, &_flags##_model, 0600) + +/* numeric input, independent bits */ +enum cat_disjoint_bits { + D2_CORE = 0, + D2_DRIVER, + D2_KMS, + D2_PRIME, + D2_ATOMIC, + D2_VBL, + D2_STATE, + D2_LEASE, + D2_DP, + D2_DRMRES }; +DECLARE_DYNDBG_CLASSMAP(map_disjoint_bits, DD_CLASS_TYPE_DISJOINT_BITS, 0, + "D2_CORE", + "D2_DRIVER", + "D2_KMS", + "D2_PRIME", + "D2_ATOMIC", + "D2_VBL", + "D2_STATE", + "D2_LEASE", + "D2_DP", + "D2_DRMRES"); +DD_SYS_WRAP(disjoint_bits, p); +DD_SYS_WRAP(disjoint_bits, T); + +/* symbolic input, independent bits */ +enum cat_disjoint_names { LOW = 11, MID, HI }; +DECLARE_DYNDBG_CLASSMAP(map_disjoint_names, DD_CLASS_TYPE_DISJOINT_NAMES, 10, + "LOW", "MID", "HI"); +DD_SYS_WRAP(disjoint_names, p); +DD_SYS_WRAP(disjoint_names, T); + +/* numeric verbosity, V2 > V1 related */ +enum cat_level_num { V0 = 14, V1, V2, V3, V4, V5, V6, V7 }; +DECLARE_DYNDBG_CLASSMAP(map_level_num, DD_CLASS_TYPE_LEVEL_NUM, 14, + "V0", "V1", "V2", "V3", "V4", "V5", "V6", "V7"); +DD_SYS_WRAP(level_num, p); +DD_SYS_WRAP(level_num, T); + +/* symbolic verbosity */ +enum cat_level_names { L0 = 22, L1, L2, L3, L4, L5, L6, L7 }; +DECLARE_DYNDBG_CLASSMAP(map_level_names, DD_CLASS_TYPE_LEVEL_NAMES, 22, + "L0", "L1", "L2", "L3", "L4", "L5", "L6", "L7"); +DD_SYS_WRAP(level_names, p); +DD_SYS_WRAP(level_names, T); + +/* stand-in for all pr_debug etc */ +#define prdbg(SYM) __pr_debug_cls(SYM, #SYM " msg\n") + +static void do_cats(void) +{ + pr_debug("doing categories\n"); + + prdbg(LOW); + prdbg(MID); + prdbg(HI); + + prdbg(D2_CORE); + prdbg(D2_DRIVER); + prdbg(D2_KMS); + prdbg(D2_PRIME); + prdbg(D2_ATOMIC); + prdbg(D2_VBL); + prdbg(D2_STATE); + prdbg(D2_LEASE); + prdbg(D2_DP); + prdbg(D2_DRMRES); +} + +static void do_levels(void) +{ + pr_debug("doing levels\n"); + + prdbg(V1); + prdbg(V2); + prdbg(V3); + prdbg(V4); + prdbg(V5); + prdbg(V6); + prdbg(V7); + + prdbg(L1); + prdbg(L2); + prdbg(L3); + prdbg(L4); + prdbg(L5); + prdbg(L6); + prdbg(L7); +} + +static void do_prints(void) +{ + do_cats(); + do_levels(); +} + +static int __init test_dynamic_debug_init(void) +{ + pr_debug("init start\n"); + do_prints(); + pr_debug("init done\n"); + return 0; +} + +static void __exit test_dynamic_debug_exit(void) +{ + pr_debug("exited\n"); +} + +module_init(test_dynamic_debug_init); +module_exit(test_dynamic_debug_exit); + +MODULE_AUTHOR("Jim Cromie "); +MODULE_DESCRIPTION("Kernel module for testing dynamic_debug"); +MODULE_LICENSE("GPL"); -- cgit v1.3.1