linux-kernel - [PATCH AUTOSEL 5.0 038/262] mm/vmalloc.c: fix kernel BUG at mm/vmalloc.c:512!

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Date:   Wed, 27 Mar 2019 13:58:13 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     "Uladzislau Rezki (Sony)" <urezki@...il.com>,
        Ingo Molnar <mingo@...e.hu>,
        Joel Fernandes <joelaf@...gle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Tejun Heo <tj@...nel.org>,
        Thomas Garnier <thgarnie@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>, linux-mm@...ck.org
Subject: [PATCH AUTOSEL 5.0 038/262] mm/vmalloc.c: fix kernel BUG at mm/vmalloc.c:512!

From: "Uladzislau Rezki (Sony)" <urezki@...il.com>

[ Upstream commit afd07389d3f4933c7f7817a92fb5e053d59a3182 ]

One of the vmalloc stress test case triggers the kernel BUG():

  <snip>
  [60.562151] ------------[ cut here ]------------
  [60.562154] kernel BUG at mm/vmalloc.c:512!
  [60.562206] invalid opcode: 0000 [#1] PREEMPT SMP PTI
  [60.562247] CPU: 0 PID: 430 Comm: vmalloc_test/0 Not tainted 4.20.0+ #161
  [60.562293] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
  [60.562351] RIP: 0010:alloc_vmap_area+0x36f/0x390
  <snip>

it can happen due to big align request resulting in overflowing of
calculated address, i.e.  it becomes 0 after ALIGN()'s fixup.

Fix it by checking if calculated address is within vstart/vend range.

Link: http://lkml.kernel.org/r/20190124115648.9433-2-urezki@gmail.com
Signed-off-by: Uladzislau Rezki (Sony) <urezki@...il.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Joel Fernandes <joelaf@...gle.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@...ymobile.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Tejun Heo <tj@...nel.org>
Cc: Thomas Garnier <thgarnie@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 mm/vmalloc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 2cd24186ba84..583630bf247d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -498,7 +498,11 @@ static struct vmap_area *alloc_vmap_area(unsigned long size,
 	}
 
 found:
-	if (addr + size > vend)
+	/*
+	 * Check also calculated address against the vstart,
+	 * because it can be 0 because of big align request.
+	 */
+	if (addr + size > vend || addr < vstart)
 		goto overflow;
 
 	va->va_start = addr;
-- 
2.19.1