[PATCH AUTOSEL 4.9 12/87] mm/vmalloc.c: fix kernel BUG at mm/vmalloc.c:512!

Sasha Levin
2019-03-27T18:45:17Z

From: "Uladzislau Rezki (Sony)" <urezki@gmail.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@gmail.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Joel Fernandes <joelaf@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@sonymobile.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Garnier <thgarnie@google.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/vmalloc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index e6aa073f01df..73afe460caf0 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -459,7 +459,11 @@ 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