linux-kernel - [PATCH 4.9 59/61] mm/vmalloc.c: dont dereference possible NULL pointer in _

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Message-Id: <20200601174022.410196971@linuxfoundation.org>
Date:   Mon,  1 Jun 2020 19:54:06 +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, Liviu Dudau <liviu@...au.co.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Chintan Pandya <cpandya@...eaurora.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Guenter Roeck <linux@...ck-us.net>
Subject: [PATCH 4.9 59/61] mm/vmalloc.c: dont dereference possible NULL pointer in __vunmap()

From: Liviu Dudau <liviu@...au.co.uk>

commit 6ade20327dbb808882888ed8ccded71e93067cf9 upstream.

find_vmap_area() can return a NULL pointer and we're going to
dereference it without checking it first.  Use the existing
find_vm_area() function which does exactly what we want and checks for
the NULL pointer.

Link: http://lkml.kernel.org/r/20181228171009.22269-1-liviu@dudau.co.uk
Fixes: f3c01d2f3ade ("mm: vmalloc: avoid racy handling of debugobjects in vunmap")
Signed-off-by: Liviu Dudau <liviu@...au.co.uk>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Chintan Pandya <cpandya@...eaurora.org>
Cc: Andrey Ryabinin <aryabinin@...tuozzo.com>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Guenter Roeck <linux@...ck-us.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 mm/vmalloc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1499,7 +1499,7 @@ static void __vunmap(const void *addr, i
 			addr))
 		return;
 
-	area = find_vmap_area((unsigned long)addr)->vm;
+	area = find_vm_area(addr);
 	if (unlikely(!area)) {
 		WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
 				addr);