perf/x86: Check if user fp is valid

commit bc6ca7b342d5ae15c3ba3081fd40271b8039fb25 upstream.

Signed-off-by: Arun Sharma <asharma@fb.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1334961696-19580-4-git-send-email-asharma@fb.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.2: also add user_addr_max() macro]
Cc: Jann Horn <jannh@google.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 7bdc8f4..336c8ae 100644 (file)
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -32,9 +32,9 @@
 
 #define segment_eq(a, b)       ((a).seg == (b).seg)
 
-#define __addr_ok(addr)                                        \
-       ((unsigned long __force)(addr) <                \
-        (current_thread_info()->addr_limit.seg))
+#define user_addr_max() (current_thread_info()->addr_limit.seg)
+#define __addr_ok(addr)        \
+       ((unsigned long __force)(addr) < user_addr_max())
 
 /*
  * Test whether a block of memory is a valid user space address.
@@ -46,14 +46,14 @@
  * This needs 33-bit (65-bit for x86_64) arithmetic. We have a carry...
  */
 
-#define __range_not_ok(addr, size)                                     \
+#define __range_not_ok(addr, size, limit)                              \
 ({                                                                     \
        unsigned long flag, roksum;                                     \
        __chk_user_ptr(addr);                                           \
        asm("add %3,%1 ; sbb %0,%0 ; cmp %1,%4 ; sbb $0,%0"             \
            : "=&r" (flag), "=r" (roksum)                               \
            : "1" (addr), "g" ((long)(size)),                           \
-             "rm" (current_thread_info()->addr_limit.seg));            \
+             "rm" (limit));                                            \
        flag;                                                           \
 })
 
@@ -76,7 +76,8 @@
  * checks that the pointer is in the user space range - after calling
  * this function, memory access functions may still return -EFAULT.
  */
-#define access_ok(type, addr, size) (likely(__range_not_ok(addr, size) == 0))
+#define access_ok(type, addr, size) \
+       (likely(__range_not_ok(addr, size, user_addr_max()) == 0))
 
 /*
  * The exception table consists of pairs of addresses: the first is the

diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index 1c041e0..57cb4fa 100644 (file)
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1461,6 +1461,12 @@ perf_callchain_kernel(struct perf_callchain_entry *entry, struct pt_regs *regs)
        dump_trace(NULL, regs, NULL, 0, &backtrace_ops, entry);
 }
 
+static inline int
+valid_user_frame(const void __user *fp, unsigned long size)
+{
+       return (__range_not_ok(fp, size, TASK_SIZE) == 0);
+}
+
 #ifdef CONFIG_COMPAT
 static inline int
 perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
@@ -1485,6 +1491,9 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
                if (fp < compat_ptr(regs->sp))
                        break;
 
+               if (!valid_user_frame(fp, sizeof(frame)))
+                       break;
+
                perf_callchain_store(entry, frame.return_address);
                fp = compat_ptr(frame.next_frame);
        }
@@ -1531,6 +1540,9 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
                if ((unsigned long)fp < regs->sp)
                        break;
 
+               if (!valid_user_frame(fp, sizeof(frame)))
+                       break;
+
                perf_callchain_store(entry, frame.return_address);
                fp = frame.next_frame;
        }