diff mbox series

[v3,5/7] powerpc/32s: Drop NULL addr verification

Message ID 8374d73eced8ac93d756e606ca64c6c3140c8ea8.1579783936.git.christophe.leroy@c-s.fr (mailing list archive)
State New, archived
Headers show
Series [v3,1/7] fs/readdir: Fix filldir() and filldir64() use of user_access_begin() | expand

Commit Message

Christophe Leroy Jan. 23, 2020, 12:59 p.m. UTC
NULL addr is a user address. Don't waste time checking it. If
someone tries to access it, it will SIGFAULT the same way as for
address 1, so no need to make it special.

The special case is when not doing a write, in that case we want
to drop the entire function. This is now handled by 'dir' param
and not by the nulity of 'to' anymore.

Also make beginning of prevent_user_access() similar
to beginning of allow_user_access(), and tell the compiler
that writing in kernel space or with a 0 length is unlikely

Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
---
v2: no change
v3: no change
---
 arch/powerpc/include/asm/book3s/32/kup.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)
diff mbox series

Patch

diff --git a/arch/powerpc/include/asm/book3s/32/kup.h b/arch/powerpc/include/asm/book3s/32/kup.h
index d765515bd1c1..3c1798e56b55 100644
--- a/arch/powerpc/include/asm/book3s/32/kup.h
+++ b/arch/powerpc/include/asm/book3s/32/kup.h
@@ -113,7 +113,7 @@  static __always_inline void allow_user_access(void __user *to, const void __user
 
 	addr = (__force u32)to;
 
-	if (!addr || addr >= TASK_SIZE || !size)
+	if (unlikely(addr >= TASK_SIZE || !size))
 		return;
 
 	end = min(addr + size, TASK_SIZE);
@@ -124,16 +124,18 @@  static __always_inline void allow_user_access(void __user *to, const void __user
 static __always_inline void prevent_user_access(void __user *to, const void __user *from,
 						u32 size, unsigned long dir)
 {
-	u32 addr = (__force u32)to;
-	u32 end = min(addr + size, TASK_SIZE);
+	u32 addr, end;
 
 	BUILD_BUG_ON(!__builtin_constant_p(dir));
 	if (!(dir & KUAP_W))
 		return;
 
-	if (!addr || addr >= TASK_SIZE || !size)
+	addr = (__force u32)to;
+
+	if (unlikely(addr >= TASK_SIZE || !size))
 		return;
 
+	end = min(addr + size, TASK_SIZE);
 	current->thread.kuap = 0;
 	kuap_update_sr(mfsrin(addr) | SR_KS, addr, end);	/* set Ks */
 }