lkml.org 
[lkml]   [2019]   [Sep]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH -tip v2] kprobes: Prohibit probing on BUG() and WARN() address
Date
Since BUG() and WARN() may use a trap (e.g. UD2 on x86) to
get the address where the BUG() has occurred, kprobes can not
do single-step out-of-line that instruction. So prohibit
probing on such address.

Without this fix, if someone put a kprobe on WARN(), the
kernel will crash with invalid opcode error instead of
outputing warning message, because kernel can not find
correct bug address.

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
---
Changes in v2:
- Add find_bug() stub function for !CONFIG_GENERIC_BUG
- Cast the p->addr to unsigned long.
---
include/linux/bug.h | 5 +++++
kernel/kprobes.c | 3 ++-
2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/bug.h b/include/linux/bug.h
index fe5916550da8..f639bd0122f3 100644
--- a/include/linux/bug.h
+++ b/include/linux/bug.h
@@ -47,6 +47,11 @@ void generic_bug_clear_once(void);

#else /* !CONFIG_GENERIC_BUG */

+static inline void *find_bug(unsigned long bugaddr)
+{
+ return NULL;
+}
+
static inline enum bug_trap_type report_bug(unsigned long bug_addr,
struct pt_regs *regs)
{
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 452151e79535..5bdf47190f09 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1514,7 +1514,8 @@ static int check_kprobe_address_safe(struct kprobe *p,
/* Ensure it is not in reserved area nor out of text */
if (!kernel_text_address((unsigned long) p->addr) ||
within_kprobe_blacklist((unsigned long) p->addr) ||
- jump_label_text_reserved(p->addr, p->addr)) {
+ jump_label_text_reserved(p->addr, p->addr) ||
+ find_bug((unsigned long) p->addr)) {
ret = -EINVAL;
goto out;
}
\
 
 \ /
  Last update: 2019-09-03 13:08    [W:0.041 / U:3.260 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site