diff options
| author | Dianzhang Chen <dianzhangchen0@gmail.com> | 2019-06-26 12:50:30 +0800 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2019-06-27 23:48:04 +0200 |
| commit | 993773d11d45c90cb1c6481c2638c3d9f092ea5b (patch) | |
| tree | ed3029d1d5c44fed104a622db172ed6c090d3481 /arch/x86/kernel/tls.c | |
| parent | 31a2fbb390fee4231281b939e1979e810f945415 (diff) | |
x86/tls: Fix possible spectre-v1 in do_get_thread_area()
The index to access the threads tls array 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 -> do_get_thread_area.
Fix this by sanitizing the user supplied index before using it to access
the p->thread.tls_array.
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/1561524630-3642-1-git-send-email-dianzhangchen0@gmail.com
Diffstat (limited to 'arch/x86/kernel/tls.c')
| -rw-r--r-- | arch/x86/kernel/tls.c | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/arch/x86/kernel/tls.c b/arch/x86/kernel/tls.c index a5b802a12212..71d3fef1edc9 100644 --- a/arch/x86/kernel/tls.c +++ b/arch/x86/kernel/tls.c @@ -5,6 +5,7 @@ #include <linux/user.h> #include <linux/regset.h> #include <linux/syscalls.h> +#include <linux/nospec.h> #include <linux/uaccess.h> #include <asm/desc.h> @@ -220,6 +221,7 @@ int do_get_thread_area(struct task_struct *p, int idx, struct user_desc __user *u_info) { struct user_desc info; + int index; if (idx == -1 && get_user(idx, &u_info->entry_number)) return -EFAULT; @@ -227,8 +229,11 @@ int do_get_thread_area(struct task_struct *p, int idx, if (idx < GDT_ENTRY_TLS_MIN || idx > GDT_ENTRY_TLS_MAX) return -EINVAL; - fill_user_desc(&info, idx, - &p->thread.tls_array[idx - GDT_ENTRY_TLS_MIN]); + index = idx - GDT_ENTRY_TLS_MIN; + index = array_index_nospec(index, + GDT_ENTRY_TLS_MAX - GDT_ENTRY_TLS_MIN + 1); + + fill_user_desc(&info, idx, &p->thread.tls_array[index]); if (copy_to_user(u_info, &info, sizeof(info))) return -EFAULT; |