From: Liam Howlett <liam.howlett@oracle.com>
Date: Wed, 7 Apr 2021 20:00:45 +0000 (+0000)
Subject: m68k: Add missing mmap_read_lock() to sys_cacheflush()
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=f829b4b212a315b912cb23fd10aaf30534bb5ce9;p=linux.git

m68k: Add missing mmap_read_lock() to sys_cacheflush()

When the superuser flushes the entire cache, the mmap_read_lock() is not
taken, but mmap_read_unlock() is called.  Add the missing
mmap_read_lock() call.

Fixes: cd2567b6850b1648 ("m68k: call find_vma with the mmap_sem held in sys_cacheflush()")
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20210407200032.764445-1-Liam.Howlett@Oracle.com
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
---

diff --git a/arch/m68k/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c
index 1c235d8f53f36..f55bdcb8e4f15 100644
--- a/arch/m68k/kernel/sys_m68k.c
+++ b/arch/m68k/kernel/sys_m68k.c
@@ -388,6 +388,8 @@ sys_cacheflush (unsigned long addr, int scope, int cache, unsigned long len)
 		ret = -EPERM;
 		if (!capable(CAP_SYS_ADMIN))
 			goto out;
+
+		mmap_read_lock(current->mm);
 	} else {
 		struct vm_area_struct *vma;