lkml.org 
[lkml]   [2018]   [Feb]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[tip:x86/pti] jump_label: Warn on failed jump_label patching attempt
Commit-ID:  5400c00440061515c5bda299c19b6e86b81be798
Gitweb: https://git.kernel.org/tip/5400c00440061515c5bda299c19b6e86b81be798
Author: Josh Poimboeuf <jpoimboe@redhat.com>
AuthorDate: Tue, 20 Feb 2018 11:37:52 -0600
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 21 Feb 2018 10:11:39 +0100

jump_label: Warn on failed jump_label patching attempt

Currently when the jump label code encounters an address which isn't
recognized by kernel_text_address(), it just silently fails.

This can be dangerous because jump labels are used in a variety of
places, and are generally expected to work. Convert the silent failure
to a warning.

This won't warn about attempted writes to tracepoints in __init code
after initmem has been freed, as those are already guarded by the
entry->code check.

Signed-off-by: Josh Poimboeuf <jpoimboe@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@suse.de>
Cc: Jason Baron <jbaron@akamai.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/de3a271c93807adb7ed48f4e946b4f9156617680.1519051220.git.jpoimboe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/jump_label.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/kernel/jump_label.c b/kernel/jump_label.c
index b717765..b2f0b47 100644
--- a/kernel/jump_label.c
+++ b/kernel/jump_label.c
@@ -367,12 +367,15 @@ static void __jump_label_update(struct static_key *key,
{
for (; (entry < stop) && (jump_entry_key(entry) == key); entry++) {
/*
- * entry->code set to 0 invalidates module init text sections
- * kernel_text_address() verifies we are not in core kernel
- * init code, see jump_label_invalidate_module_init().
+ * An entry->code of 0 indicates an entry which has been
+ * disabled because it was in an init text area.
*/
- if (entry->code && kernel_text_address(entry->code))
- arch_jump_label_transform(entry, jump_label_type(entry));
+ if (entry->code) {
+ if (kernel_text_address(entry->code))
+ arch_jump_label_transform(entry, jump_label_type(entry));
+ else
+ WARN_ONCE(1, "can't patch jump_label at %pS", (void *)entry->code);
+ }
}
}

\
 
 \ /
  Last update: 2018-02-21 11:50    [W:0.091 / U:0.096 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site