linux-kernel - [PATCH 5.11 284/601] m68k: Add missing mmap_read_lock() to sys

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Date:   Wed, 12 May 2021 16:46:01 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        "Matthew Wilcox (Oracle)" <willy@...radead.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.11 284/601] m68k: Add missing mmap_read_lock() to sys_cacheflush()

From: Liam Howlett <liam.howlett@...cle.com>

[ Upstream commit f829b4b212a315b912cb23fd10aaf30534bb5ce9 ]

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@...cle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@...radead.org>
Link: https://lore.kernel.org/r/20210407200032.764445-1-Liam.Howlett@Oracle.com
Signed-off-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/m68k/kernel/sys_m68k.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/m68k/kernel/sys_m68k.c b/arch/m68k/kernel/sys_m68k.c
index 1c235d8f53f3..f55bdcb8e4f1 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;
 
-- 
2.30.2