lkml.org 
[lkml]   [2019]   [Apr]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.14 001/121] arm64: debug: Dont propagate UNKNOWN FAR into si_code for debug signals
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Will Deacon <will.deacon@arm.com>

commit b9a4b9d084d978f80eb9210727c81804588b42ff upstream.

FAR_EL1 is UNKNOWN for all debug exceptions other than those caused by
taking a hardware watchpoint. Unfortunately, if a debug handler returns
a non-zero value, then we will propagate the UNKNOWN FAR value to
userspace via the si_addr field of the SIGTRAP siginfo_t.

Instead, let's set si_addr to take on the PC of the faulting instruction,
which we have available in the current pt_regs.

Cc: <stable@vger.kernel.org>
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


---
arch/arm64/mm/fault.c | 11 ++++++-----
1 file changed, 6 insertions(+), 5 deletions(-)

--- a/arch/arm64/mm/fault.c
+++ b/arch/arm64/mm/fault.c
@@ -834,11 +834,12 @@ void __init hook_debug_fault_code(int nr
debug_fault_info[nr].name = name;
}

-asmlinkage int __exception do_debug_exception(unsigned long addr,
+asmlinkage int __exception do_debug_exception(unsigned long addr_if_watchpoint,
unsigned int esr,
struct pt_regs *regs)
{
const struct fault_info *inf = debug_fault_info + DBG_ESR_EVT(esr);
+ unsigned long pc = instruction_pointer(regs);
struct siginfo info;
int rv;

@@ -849,19 +850,19 @@ asmlinkage int __exception do_debug_exce
if (interrupts_enabled(regs))
trace_hardirqs_off();

- if (user_mode(regs) && instruction_pointer(regs) > TASK_SIZE)
+ if (user_mode(regs) && pc > TASK_SIZE)
arm64_apply_bp_hardening();

- if (!inf->fn(addr, esr, regs)) {
+ if (!inf->fn(addr_if_watchpoint, esr, regs)) {
rv = 1;
} else {
pr_alert("Unhandled debug exception: %s (0x%08x) at 0x%016lx\n",
- inf->name, esr, addr);
+ inf->name, esr, pc);

info.si_signo = inf->sig;
info.si_errno = 0;
info.si_code = inf->code;
- info.si_addr = (void __user *)addr;
+ info.si_addr = (void __user *)pc;
arm64_notify_die("", regs, &info, 0);
rv = 0;
}

\
 
 \ /
  Last update: 2019-04-04 11:53    [W:0.306 / U:68.492 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site