perf/x86: Check if user fp is valid

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>

2 files changed, 18 insertions, 6 deletions

diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
index 04cd6882308e..e1f3a17034fc 100644
--- a/arch/x86/include/asm/uaccess.h
+++ b/arch/x86/include/asm/uaccess.h
@@ -33,9 +33,8 @@
 #define segment_eq(a, b)        ((a).seg == (b).seg)
 
 #define user_addr_max() (current_thread_info()->addr_limit.seg)
-#define __addr_ok(addr)                                 \
-        ((unsigned long __force)(addr) <                \
-         (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.
@@ -47,14 +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;                                                           \
 })
 
@@ -77,7 +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 relative to the
diff --git a/arch/x86/kernel/cpu/perf_event.c b/arch/x86/kernel/cpu/perf_event.c
index e78bc256aea8..c4706cf9c011 100644
--- a/arch/x86/kernel/cpu/perf_event.c
+++ b/arch/x86/kernel/cpu/perf_event.c
@@ -1757,6 +1757,12 @@ 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
 
 #include <asm/compat.h>
@@ -1781,6 +1787,9 @@ perf_callchain_user32(struct pt_regs *regs, struct perf_callchain_entry *entry)
                 if (bytes != sizeof(frame))
                         break;
 
+                if (!valid_user_frame(fp, sizeof(frame)))
+                        break;
+
                 perf_callchain_store(entry, frame.return_address);
                 fp = compat_ptr(frame.next_frame);
         }
@@ -1824,6 +1833,9 @@ perf_callchain_user(struct perf_callchain_entry *entry, struct pt_regs *regs)
                 if (bytes != sizeof(frame))
                         break;
 
+                if (!valid_user_frame(fp, sizeof(frame)))
+                        break;
+
                 perf_callchain_store(entry, frame.return_address);
                 fp = frame.next_frame;
         }