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authorMiroslav Benes <mbenes@suse.cz>2019-06-20 14:10:37 +0200
committerMiroslav Benes <mbenes@suse.cz>2019-06-20 14:10:37 +0200
commit3eec3e8321c34fd28196be2a7a52cf987ac341b6 (patch)
tree65f8d098344e57bea11332d241734fc77a889c61
parent0a4b38d7b1a1bad3c39c07516bbd2ad76004a64c (diff)
module: Fix livepatch/ftrace module text permissions race
(bsc#1071995 fate#323487).
-rw-r--r--patches.suse/module-fix-livepatch-ftrace-module-text-permissions-race.patch170
-rw-r--r--series.conf1
2 files changed, 171 insertions, 0 deletions
diff --git a/patches.suse/module-fix-livepatch-ftrace-module-text-permissions-race.patch b/patches.suse/module-fix-livepatch-ftrace-module-text-permissions-race.patch
new file mode 100644
index 0000000000..66088c57bc
--- /dev/null
+++ b/patches.suse/module-fix-livepatch-ftrace-module-text-permissions-race.patch
@@ -0,0 +1,170 @@
+From: Josh Poimboeuf <jpoimboe@redhat.com>
+Date: Thu, 13 Jun 2019 20:07:22 -0500
+Subject: module: Fix livepatch/ftrace module text permissions race
+Git-commit: 9f255b632bf12c4dd7fc31caee89aa991ef75176
+Patch-mainline: v5.2-rc5
+References: bsc#1071995 fate#323487
+
+It's possible for livepatch and ftrace to be toggling a module's text
+permissions at the same time, resulting in the following panic:
+
+ BUG: unable to handle page fault for address: ffffffffc005b1d9
+ #PF: supervisor write access in kernel mode
+ #PF: error_code(0x0003) - permissions violation
+ PGD 3ea0c067 P4D 3ea0c067 PUD 3ea0e067 PMD 3cc13067 PTE 3b8a1061
+ Oops: 0003 [#1] PREEMPT SMP PTI
+ CPU: 1 PID: 453 Comm: insmod Tainted: G O K 5.2.0-rc1-a188339ca5 #1
+ Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-20181126_142135-anatol 04/01/2014
+ RIP: 0010:apply_relocate_add+0xbe/0x14c
+ Code: fa 0b 74 21 48 83 fa 18 74 38 48 83 fa 0a 75 40 eb 08 48 83 38 00 74 33 eb 53 83 38 00 75 4e 89 08 89 c8 eb 0a 83 38 00 75 43 <89> 08 48 63 c1 48 39 c8 74 2e eb 48 83 38 00 75 32 48 29 c1 89 08
+ RSP: 0018:ffffb223c00dbb10 EFLAGS: 00010246
+ RAX: ffffffffc005b1d9 RBX: 0000000000000000 RCX: ffffffff8b200060
+ RDX: 000000000000000b RSI: 0000004b0000000b RDI: ffff96bdfcd33000
+ RBP: ffffb223c00dbb38 R08: ffffffffc005d040 R09: ffffffffc005c1f0
+ R10: ffff96bdfcd33c40 R11: ffff96bdfcd33b80 R12: 0000000000000018
+ R13: ffffffffc005c1f0 R14: ffffffffc005e708 R15: ffffffff8b2fbc74
+ FS: 00007f5f447beba8(0000) GS:ffff96bdff900000(0000) knlGS:0000000000000000
+ CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
+ CR2: ffffffffc005b1d9 CR3: 000000003cedc002 CR4: 0000000000360ea0
+ DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
+ DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
+ Call Trace:
+ klp_init_object_loaded+0x10f/0x219
+ ? preempt_latency_start+0x21/0x57
+ klp_enable_patch+0x662/0x809
+ ? virt_to_head_page+0x3a/0x3c
+ ? kfree+0x8c/0x126
+ patch_init+0x2ed/0x1000 [livepatch_test02]
+ ? 0xffffffffc0060000
+ do_one_initcall+0x9f/0x1c5
+ ? kmem_cache_alloc_trace+0xc4/0xd4
+ ? do_init_module+0x27/0x210
+ do_init_module+0x5f/0x210
+ load_module+0x1c41/0x2290
+ ? fsnotify_path+0x3b/0x42
+ ? strstarts+0x2b/0x2b
+ ? kernel_read+0x58/0x65
+ __do_sys_finit_module+0x9f/0xc3
+ ? __do_sys_finit_module+0x9f/0xc3
+ __x64_sys_finit_module+0x1a/0x1c
+ do_syscall_64+0x52/0x61
+ entry_SYSCALL_64_after_hwframe+0x44/0xa9
+
+The above panic occurs when loading two modules at the same time with
+ftrace enabled, where at least one of the modules is a livepatch module:
+
+CPU0 CPU1
+klp_enable_patch()
+ klp_init_object_loaded()
+ module_disable_ro()
+ ftrace_module_enable()
+ ftrace_arch_code_modify_post_process()
+ set_all_modules_text_ro()
+ klp_write_object_relocations()
+ apply_relocate_add()
+ *patches read-only code* - BOOM
+
+A similar race exists when toggling ftrace while loading a livepatch
+module.
+
+Fix it by ensuring that the livepatch and ftrace code patching
+operations -- and their respective permissions changes -- are protected
+by the text_mutex.
+
+Link: http://lkml.kernel.org/r/ab43d56ab909469ac5d2520c5d944ad6d4abd476.1560474114.git.jpoimboe@redhat.com
+
+Reported-by: Johannes Erdfelt <johannes@erdfelt.com>
+Fixes: 444d13ff10fb ("modules: add ro_after_init support")
+Acked-by: Jessica Yu <jeyu@kernel.org>
+Reviewed-by: Petr Mladek <pmladek@suse.com>
+Reviewed-by: Miroslav Benes <mbenes@suse.cz>
+Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
+Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
+Acked-by: Miroslav Benes <mbenes@suse.cz>
+---
+ kernel/livepatch/core.c | 6 ++++++
+ kernel/trace/ftrace.c | 10 +++++++++-
+ 2 files changed, 15 insertions(+), 1 deletion(-)
+
+--- a/kernel/livepatch/core.c
++++ b/kernel/livepatch/core.c
+@@ -30,6 +30,7 @@
+ #include <linux/elf.h>
+ #include <linux/moduleloader.h>
+ #include <linux/completion.h>
++#include <linux/memory.h>
+ #include <asm/cacheflush.h>
+ #include "core.h"
+ #include "patch.h"
+@@ -729,16 +730,21 @@ static int klp_init_object_loaded(struct
+ struct klp_func *func;
+ int ret;
+
++ mutex_lock(&text_mutex);
++
+ module_disable_ro(patch->mod);
+ ret = klp_write_object_relocations(patch->mod, obj);
+ if (ret) {
+ module_enable_ro(patch->mod, true);
++ mutex_unlock(&text_mutex);
+ return ret;
+ }
+
+ arch_klp_init_object_loaded(patch, obj);
+ module_enable_ro(patch->mod, true);
+
++ mutex_unlock(&text_mutex);
++
+ klp_for_each_func(obj, func) {
+ ret = klp_find_object_symbol(obj->name, func->old_name,
+ func->old_sympos,
+--- a/kernel/trace/ftrace.c
++++ b/kernel/trace/ftrace.c
+@@ -33,6 +33,7 @@
+ #include <linux/list.h>
+ #include <linux/hash.h>
+ #include <linux/rcupdate.h>
++#include <linux/memory.h>
+
+ #include <trace/events/sched.h>
+
+@@ -2629,10 +2630,12 @@ static void ftrace_run_update_code(int c
+ {
+ int ret;
+
++ mutex_lock(&text_mutex);
++
+ ret = ftrace_arch_code_modify_prepare();
+ FTRACE_WARN_ON(ret);
+ if (ret)
+- return;
++ goto out_unlock;
+
+ /*
+ * By default we use stop_machine() to modify the code.
+@@ -2644,6 +2647,9 @@ static void ftrace_run_update_code(int c
+
+ ret = ftrace_arch_code_modify_post_process();
+ FTRACE_WARN_ON(ret);
++
++out_unlock:
++ mutex_unlock(&text_mutex);
+ }
+
+ static void ftrace_run_modify_code(struct ftrace_ops *ops, int command,
+@@ -5409,6 +5415,7 @@ void ftrace_module_enable(struct module
+ struct ftrace_page *pg;
+
+ mutex_lock(&ftrace_lock);
++ mutex_lock(&text_mutex);
+
+ if (ftrace_disabled)
+ goto out_unlock;
+@@ -5469,6 +5476,7 @@ void ftrace_module_enable(struct module
+ ftrace_arch_code_modify_post_process();
+
+ out_unlock:
++ mutex_unlock(&text_mutex);
+ mutex_unlock(&ftrace_lock);
+ }
+
diff --git a/series.conf b/series.conf
index 00d8a8da60..06b0e5c4d1 100644
--- a/series.conf
+++ b/series.conf
@@ -22581,6 +22581,7 @@
patches.drivers/Revert-ALSA-hda-realtek-Improve-the-headset-mic-for-.patch
patches.drm/drm-i915-sdvo-Implement-proper-HDMI-audio-support-fo.patch
patches.drm/drm-i915-perf-fix-whitelist-on-Gen10.patch
+ patches.suse/module-fix-livepatch-ftrace-module-text-permissions-race.patch
patches.drivers/usb-dwc2-Fix-DMA-cache-alignment-issues.patch
patches.drivers/platform-x86-mlx-platform-Fix-parent-device-in-i2c-m.patch
patches.drivers/ras-cec-fix-binary-search-function.patch