lkml.org 
[lkml]   [2018]   [Apr]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [PATCH v3] vmw_balloon: fixing double free when batching mode is off
Date
Ping. Please consider it for inclusion for rc4.

Nadav Amit <namit@vmware.com> wrote:

> From: Gil Kupfer <gilkup@gmail.com>
>
> The balloon.page field is used for two different purposes if batching is
> on or off. If batching is on, the field point to the page which is used
> to communicate with with the hypervisor. If it is off, balloon.page
> points to the page that is about to be (un)locked.
>
> Unfortunately, this dual-purpose of the field introduced a bug: when the
> balloon is popped (e.g., when the machine is reset or the balloon driver
> is explicitly removed), the balloon driver frees, unconditionally, the
> page that is held in balloon.page. As a result, if batching is
> disabled, this leads to double freeing the last page that is sent to the
> hypervisor.
>
> The following error occurs during rmmod when kernel checkers are on, and
> the balloon is not empty:
>
> [ 42.307653] ------------[ cut here ]------------
> [ 42.307657] Kernel BUG at ffffffffba1e4b28 [verbose debug info unavailable]
> [ 42.307720] invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
> [ 42.312512] Modules linked in: vmw_vsock_vmci_transport vsock ppdev joydev vmw_balloon(-) input_leds serio_raw vmw_vmci parport_pc shpchp parport i2c_piix4 nfit mac_hid autofs4 vmwgfx drm_kms_helper hid_generic syscopyarea sysfillrect usbhid sysimgblt fb_sys_fops hid ttm mptspi scsi_transport_spi ahci mptscsih drm psmouse vmxnet3 libahci mptbase pata_acpi
> [ 42.312766] CPU: 10 PID: 1527 Comm: rmmod Not tainted 4.12.0+ #5
> [ 42.312803] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 09/30/2016
> [ 42.313042] task: ffff9bf9680f8000 task.stack: ffffbfefc1638000
> [ 42.313290] RIP: 0010:__free_pages+0x38/0x40
> [ 42.313510] RSP: 0018:ffffbfefc163be98 EFLAGS: 00010246
> [ 42.313731] RAX: 000000000000003e RBX: ffffffffc02b9720 RCX: 0000000000000006
> [ 42.313972] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9bf97e08e0a0
> [ 42.314201] RBP: ffffbfefc163be98 R08: 0000000000000000 R09: 0000000000000000
> [ 42.314435] R10: 0000000000000000 R11: 0000000000000000 R12: ffffffffc02b97e4
> [ 42.314505] R13: ffffffffc02b9748 R14: ffffffffc02b9728 R15: 0000000000000200
> [ 42.314550] FS: 00007f3af5fec700(0000) GS:ffff9bf97e080000(0000) knlGS:0000000000000000
> [ 42.314599] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 42.314635] CR2: 00007f44f6f4ab24 CR3: 00000003a7d12000 CR4: 00000000000006e0
> [ 42.314864] Call Trace:
> [ 42.315774] vmballoon_pop+0x102/0x130 [vmw_balloon]
> [ 42.315816] vmballoon_exit+0x42/0xd64 [vmw_balloon]
> [ 42.315853] SyS_delete_module+0x1e2/0x250
> [ 42.315891] entry_SYSCALL_64_fastpath+0x23/0xc2
> [ 42.315924] RIP: 0033:0x7f3af5b0e8e7
> [ 42.315949] RSP: 002b:00007fffe6ce0148 EFLAGS: 00000206 ORIG_RAX: 00000000000000b0
> [ 42.315996] RAX: ffffffffffffffda RBX: 000055be676401e0 RCX: 00007f3af5b0e8e7
> [ 42.316951] RDX: 000000000000000a RSI: 0000000000000800 RDI: 000055be67640248
> [ 42.317887] RBP: 0000000000000003 R08: 0000000000000000 R09: 1999999999999999
> [ 42.318845] R10: 0000000000000883 R11: 0000000000000206 R12: 00007fffe6cdf130
> [ 42.319755] R13: 0000000000000000 R14: 0000000000000000 R15: 000055be676401e0
> [ 42.320606] Code: c0 74 1c f0 ff 4f 1c 74 02 5d c3 85 f6 74 07 e8 0f d8 ff ff 5d c3 31 f6 e8 c6 fb ff ff 5d c3 48 c7 c6 c8 0f c5 ba e8 58 be 02 00 <0f> 0b 66 0f 1f 44 00 00 66 66 66 66 90 48 85 ff 75 01 c3 55 48
> [ 42.323462] RIP: __free_pages+0x38/0x40 RSP: ffffbfefc163be98
> [ 42.325735] ---[ end trace 872e008e33f81508 ]---
>
> To solve the bug, we eliminate the dual purpose of balloon.page.
>
> Fixes: f220a80f0c2e ("VMware balloon: add batching to the vmw_balloon.")
> Cc: stable@vger.kernel.org
> Reported-by: Oleksandr Natalenko <onatalen@redhat.com>
> Signed-off-by: Gil Kupfer <gilkup@gmail.com>
> Signed-off-by: Nadav Amit <namit@vmware.com>
> Reviewed-by: Xavier Deguillard <xdeguillard@vmware.com>
> ---
> drivers/misc/vmw_balloon.c | 23 +++++++----------------
> 1 file changed, 7 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/misc/vmw_balloon.c b/drivers/misc/vmw_balloon.c
> index 9047c0a529b2..efd733472a35 100644
> --- a/drivers/misc/vmw_balloon.c
> +++ b/drivers/misc/vmw_balloon.c
> @@ -576,15 +576,9 @@ static void vmballoon_pop(struct vmballoon *b)
> }
> }
>
> - if (b->batch_page) {
> - vunmap(b->batch_page);
> - b->batch_page = NULL;
> - }
> -
> - if (b->page) {
> - __free_page(b->page);
> - b->page = NULL;
> - }
> + /* Clearing the batch_page unconditionally has no adverse effect */
> + free_page((unsigned long)b->batch_page);
> + b->batch_page = NULL;
> }
>
> /*
> @@ -991,16 +985,13 @@ static const struct vmballoon_ops vmballoon_batched_ops = {
>
> static bool vmballoon_init_batching(struct vmballoon *b)
> {
> - b->page = alloc_page(VMW_PAGE_ALLOC_NOSLEEP);
> - if (!b->page)
> - return false;
> + struct page *page;
>
> - b->batch_page = vmap(&b->page, 1, VM_MAP, PAGE_KERNEL);
> - if (!b->batch_page) {
> - __free_page(b->page);
> + page = alloc_page(GFP_KERNEL | __GFP_ZERO);
> + if (!page)
> return false;
> - }
>
> + b->batch_page = page_address(page);
> return true;
> }
>
> --
> 2.14.1


\
 
 \ /
  Last update: 2018-04-30 19:31    [W:0.130 / U:33.464 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site