[FIX] Preload: context fix

Removed redundant access_ok(), copy_from_user() replaced
with read_proc_vm_atomic().
It is done to prevent sleeping in atomic context.

Change-Id: Ib260e0f89b5a0a034c8e591361d4ab1d2ffa4b95
Signed-off-by: Alexander Aksenov <a.aksenov@samsung.com>

diff --git a/preload/preload_module.c b/preload/preload_module.c
index 0563eb7..b23e38d 100644 (file)
--- a/preload/preload_module.c
+++ b/preload/preload_module.c
@@ -10,6 +10,7 @@
 #include <linux/types.h>
 #include <linux/uaccess.h>
 #include <kprobe/swap_kprobes.h>
+#include <kprobe/swap_kprobes_deps.h>
 #include <us_manager/us_manager_common.h>
 #include <us_manager/sspt/sspt_page.h>
 #include <us_manager/sspt/sspt_file.h>
@@ -354,12 +355,6 @@ is_handlers_call_out:
 static inline int __msg_sanitization(char *user_msg, size_t len,
                                     char *call_type_p, char *caller_p)
 {
-       int ret;
-
-       ret = access_ok(VERIFY_READ, (unsigned long)user_msg, (unsigned long)len);
-       if (ret == 0)
-               return -EINVAL;
-
        if ((call_type_p < user_msg) || (call_type_p > user_msg + len) ||
            (caller_p < user_msg) || (caller_p > user_msg + len))
                return -EINVAL;
@@ -785,6 +780,7 @@ static int write_msg_handler(struct kprobe *p, struct pt_regs *regs)
        bool drop;
        int ret;
 
+       /* FIXME: swap_get_uarg uses get_user(), it might sleep */
        user_buf = (char *)swap_get_uarg(regs, 0);
        len = swap_get_uarg(regs, 1);
        call_type_p = (char *)swap_get_uarg(regs, 2);
@@ -801,15 +797,16 @@ static int write_msg_handler(struct kprobe *p, struct pt_regs *regs)
        if (ret == 0 && drop)
                return 0;
 
-       buf = kmalloc(len, GFP_KERNEL);
+       buf = kmalloc(len, GFP_ATOMIC);
        if (buf == NULL) {
                printk(PRELOAD_PREFIX "No mem for buffer! Size = %d\n", len);
                return 0;
        }
 
-       if (copy_from_user(buf, user_buf, len)) {
+       ret = read_proc_vm_atomic(current, (unsigned long)user_buf, buf, len);
+       if (ret < 0) {
                printk(PRELOAD_PREFIX "Cannot copy data from userspace! Size = %d"
-                                     " ptr 0x%lx\n", len, (unsigned long)user_buf);
+                                     " ptr 0x%lx ret %d\n", len, (unsigned long)user_buf, ret);
                goto write_msg_fail;
        }