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kprobes: Prohibit probing on BUG() and WARN() address 

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>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S . Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naveen N . Rao <naveen.n.rao@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lkml.kernel.org/r/156750890133.19112.3393666300746167111.stgit@devnote2
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Masami Hiramatsu 2019-09-03 20:08:21 +09:00 committed by Ingo Molnar
parent d9f3b450f2
commit e336b40277
2 changed files with 7 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/bug.h
View File

@ -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)
{

3
kernel/kprobes.c
View File

@ -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;
}