From: Masami Hiramatsu mhiramat@kernel.org
[ Upstream commit e336b4027775cb458dc713745e526fa1a1996b2a ]
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@devno... Signed-off-by: Ingo Molnar mingo@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 292d6a10b0c26..0faae96302bda 100644 --- a/include/linux/bug.h +++ b/include/linux/bug.h @@ -114,6 +114,11 @@ int is_valid_bugaddr(unsigned long addr);
#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 e2845dd53b30b..11863e2b01c25 100644 --- a/kernel/kprobes.c +++ b/kernel/kprobes.c @@ -1454,7 +1454,8 @@ 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; }