diff options
| author | Dianzhang Chen <dianzhangchen0@gmail.com> | 2019-06-25 23:30:17 +0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-10-31 22:14:59 +0000 |
| commit | 58ba5001051390e30d726fc44240ed182aa26c1b (patch) | |
| tree | 52b2cc48e123d49b9f94d260c26920197da298f6 /arch | |
| parent | c21c17039e93b5d4c1db276e448b5a197ae0963c (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
Link: https://lkml.kernel.org/r/1561476617-3759-1-git-send-email-dianzhangchen0@gmail.com
[bwh: Backported to 3.16: fold in fix-up from commit 223cea6a4f05
"Merge branch 'x86-pti-for-linus' of ..."]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/x86/kernel/ptrace.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c index 8072696aa20f..619f0c77f203 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 <asm/uaccess.h> #include <asm/pgtable.h> @@ -707,7 +708,8 @@ static unsigned long ptrace_get_debugreg(struct task_struct *tsk, int n) unsigned long val = 0; if (n < HBP_NUM) { - struct perf_event *bp = thread->ptrace_bps[n]; + int index = array_index_nospec(n, HBP_NUM); + struct perf_event *bp = thread->ptrace_bps[index]; if (bp) val = bp->hw.info.address; |