[063/165] syscalls: use uaccess_kernel in addr_limit_user_check

Commit Message

Andrew Morton Aug. 12, 2020, 1:33 a.m. UTC

From: Christoph Hellwig <[e-mail]>
Subject: syscalls: use uaccess_kernel in addr_limit_user_check

Patch series "clean up address limit helpers", v2.

In preparation for eventually phasing out direct use of set_fs(), this
series removes the segment_eq() arch helper that is only used to implement
or duplicate the uaccess_kernel() API, and then adds descriptive helpers
to force the kernel address limit.


This patch (of 6):

Use the uaccess_kernel helper instead of duplicating it.

[[e-mail]: arm: don't call addr_limit_user_check for nommu]
  Link: http://lkml.kernel.org/r/[e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Christoph Hellwig <[e-mail]>
Acked-by: Linus Torvalds <[e-mail]>
Tested-by: Guenter Roeck <[e-mail]>
Cc: Nick Hu <[e-mail]>
Cc: Greentime Hu <[e-mail]>
Cc: Vincent Chen <[e-mail]>
Cc: Paul Walmsley <[e-mail]>
Cc: Palmer Dabbelt <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 arch/arm/kernel/signal.c |    2 ++
 include/linux/syscalls.h |    2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

Patch

--- a/arch/arm/kernel/signal.c~syscalls-use-uaccess_kernel-in-addr_limit_user_check
+++ a/arch/arm/kernel/signal.c
@@ -713,7 +713,9 @@  struct page *get_signal_page(void)
 /* Defer to generic check */
 asmlinkage void addr_limit_check_failed(void)
 {
+#ifdef CONFIG_MMU
 	addr_limit_user_check();
+#endif
 }
 
 #ifdef CONFIG_DEBUG_RSEQ
--- a/include/linux/syscalls.h~syscalls-use-uaccess_kernel-in-addr_limit_user_check
+++ a/include/linux/syscalls.h
@@ -263,7 +263,7 @@  static inline void addr_limit_user_check
 		return;
 #endif
 
-	if (CHECK_DATA_CORRUPTION(!segment_eq(get_fs(), USER_DS),
+	if (CHECK_DATA_CORRUPTION(uaccess_kernel(),
 				  "Invalid address limit on user-mode return"))
 		force_sig(SIGKILL);