diff options
| author | Peter Zijlstra <[email protected]> | 2019-08-29 10:24:45 +0200 |
|---|---|---|
| committer | Peter Zijlstra <[email protected]> | 2019-09-02 14:22:38 +0200 |
| commit | 9b8bd476e78e89c9ea26c3b435ad0201c3d7dbf5 (patch) | |
| tree | b9a0554a17fe68adb8624c7845fdb1d8e0d7d324 | |
| parent | 29d9a0b50736768f042752070e5cdf4e4d4c00df (diff) | |
x86/uaccess: Don't leak the AC flags into __get_user() argument evaluation
Identical to __put_user(); the __get_user() argument evalution will too
leak UBSAN crud into the __uaccess_begin() / __uaccess_end() region.
While uncommon this was observed to happen for:
drivers/xen/gntdev.c: if (__get_user(old_status, batch->status[i]))
where UBSAN added array bound checking.
This complements commit:
6ae865615fc4 ("x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation")
Tested-by Sedat Dilek <[email protected]>
Reported-by: Randy Dunlap <[email protected]>
Signed-off-by: Peter Zijlstra (Intel) <[email protected]>
Reviewed-by: Josh Poimboeuf <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Cc: [email protected]
Cc: Randy Dunlap <[email protected]>
Cc: [email protected]
Cc: Josh Poimboeuf <[email protected]>
Link: https://lkml.kernel.org/r/[email protected]
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 9c4435307ff8..35c225ede0e4 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -444,8 +444,10 @@ __pu_label: \ ({ \ int __gu_err; \ __inttype(*(ptr)) __gu_val; \ + __typeof__(ptr) __gu_ptr = (ptr); \ + __typeof__(size) __gu_size = (size); \ __uaccess_begin_nospec(); \ - __get_user_size(__gu_val, (ptr), (size), __gu_err, -EFAULT); \ + __get_user_size(__gu_val, __gu_ptr, __gu_size, __gu_err, -EFAULT); \ __uaccess_end(); \ (x) = (__force __typeof__(*(ptr)))__gu_val; \ __builtin_expect(__gu_err, 0); \ |