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authorKees Cook <keescook@chromium.org>2019-04-06 08:52:11 -0700
committerKees Cook <keescook@chromium.org>2019-04-07 10:38:31 -0700
commit2bf8496f6e9b7e9a557f65eb95eab16fea7958c7 (patch)
tree057dce6a506b6507436b2d8225198a0e269df0e8 /drivers/misc/lkdtm
parent8c2ffd9174779014c3fe1f96d9dc3641d9175f00 (diff)
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lkdtm/usercopy: Moves the KERNEL_DS test to non-canonical
The prior implementation of the KERNEL_DS fault checking would work on any unmapped kernel address, but this was narrowed to the non-canonical range instead. This adjusts the LKDTM test to match. Fixes: 00c42373d397 ("x86-64: add warning for non-canonical user access address dereferences") Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'drivers/misc/lkdtm')
-rw-r--r--drivers/misc/lkdtm/usercopy.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c
index d5a0e7f1813b..e172719dd86d 100644
--- a/drivers/misc/lkdtm/usercopy.c
+++ b/drivers/misc/lkdtm/usercopy.c
@@ -324,14 +324,16 @@ free_user:
void lkdtm_USERCOPY_KERNEL_DS(void)
{
- char __user *user_ptr = (char __user *)ERR_PTR(-EINVAL);
+ char __user *user_ptr =
+ (char __user *)(0xFUL << (sizeof(unsigned long) * 8 - 4));
mm_segment_t old_fs = get_fs();
char buf[10] = {0};
- pr_info("attempting copy_to_user on unmapped kernel address\n");
+ pr_info("attempting copy_to_user() to noncanonical address: %px\n",
+ user_ptr);
set_fs(KERNEL_DS);
- if (copy_to_user(user_ptr, buf, sizeof(buf)))
- pr_info("copy_to_user un unmapped kernel address failed\n");
+ if (copy_to_user(user_ptr, buf, sizeof(buf)) == 0)
+ pr_err("copy_to_user() to noncanonical address succeeded!?\n");
set_fs(old_fs);
}