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-rw-r--r--include/linux/uaccess.h8
1 files changed, 8 insertions, 0 deletions
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
index 67918c22339c..76c3fe325101 100644
--- a/include/linux/uaccess.h
+++ b/include/linux/uaccess.h
@@ -65,14 +65,22 @@ static inline unsigned long __copy_from_user_nocache(void *to,
65 * do_page_fault() doesn't attempt to take mmap_sem. This makes 65 * do_page_fault() doesn't attempt to take mmap_sem. This makes
66 * probe_kernel_address() suitable for use within regions where the caller 66 * probe_kernel_address() suitable for use within regions where the caller
67 * already holds mmap_sem, or other locks which nest inside mmap_sem. 67 * already holds mmap_sem, or other locks which nest inside mmap_sem.
68 * This must be a macro because __get_user() needs to know the types of the
69 * args.
70 *
71 * We don't include enough header files to be able to do the set_fs(). We
72 * require that the probe_kernel_address() caller will do that.
68 */ 73 */
69#define probe_kernel_address(addr, retval) \ 74#define probe_kernel_address(addr, retval) \
70 ({ \ 75 ({ \
71 long ret; \ 76 long ret; \
77 mm_segment_t old_fs = get_fs(); \
72 \ 78 \
79 set_fs(KERNEL_DS); \
73 pagefault_disable(); \ 80 pagefault_disable(); \
74 ret = __get_user(retval, addr); \ 81 ret = __get_user(retval, addr); \
75 pagefault_enable(); \ 82 pagefault_enable(); \
83 set_fs(old_fs); \
76 ret; \ 84 ret; \
77 }) 85 })
78 86