diff options
| author | Dianzhang Chen <dianzhangchen0@gmail.com> | 2019-06-25 23:30:17 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-14 08:11:17 +0200 |
| commit | 68ff28291a4f52861542f1387fe1d5b9cebd3851 (patch) | |
| tree | 6e5fc9f64cd6cb8d570a656ea9b386877c57c148 | |
| parent | d8e26651ce8d2dd4f87315642658b4e21f6471d1 (diff) | |
x86/ptrace: Fix possible spectre-v1 in ptrace_get_debugreg()
commit 31a2fbb390fee4231281b939e1979e810f945415 upstream.
The index to access the threads ptrace_bps is controlled by userspace via
syscall: sys_ptrace(), hence leading to a potential exploitation of the
Spectre variant 1 vulnerability.
The index can be controlled from:
ptrace -> arch_ptrace -> ptrace_get_debugreg.
Fix this by sanitizing the user supplied index before using it access
thread->ptrace_bps.
Signed-off-by: Dianzhang Chen <dianzhangchen0@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: bp@alien8.de
Cc: hpa@zytor.com
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1561476617-3759-1-git-send-email-dianzhangchen0@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index e2ee403865eb..aeba77881d85 100644 --- a/arch/x86/kernel/ptrace.c +++ b/arch/x86/kernel/ptrace.c @@ -24,6 +24,7 @@ #include <linux/rcupdate.h> #include <linux/export.h> #include <linux/context_tracking.h> +#include <linux/nospec.h> #include <linux/uaccess.h> #include <asm/pgtable.h> @@ -651,9 +652,11 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n) { struct thread_struct *thread = &tsk->thread; unsigned long val = 0; + int index = n; if (n < HBP_NUM) { - struct perf_event *bp = thread->ptrace_bps[n]; + struct perf_event *bp = thread->ptrace_bps[index]; + index = array_index_nospec(index, HBP_NUM); if (bp) val = bp->hw.info.address; |