Re: [PATCH RFC 1/1] x86: fix bad memory access in fb_is_primary_device()

From: Ingo Molnar
Date: Tue Feb 16 2016 - 02:55:34 EST

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(I've Cc:-ed the EFI-FB and FB gents. Mail quoted below.)

* Alexander Popov <alpopov@xxxxxxxxxxxxxx> wrote:

> Currently the code in fb_is_primary_device() contains to_pci_dev() macro
> which is applied to dev from struct fb_info. In some cases this causes
> bad memory access when fb_is_primary_device() handles fb_info of efifb.
> The reason is that fb dev of efifb is embedded into struct platform_device
> but not into struct pci_dev.
>
> We can fix this by checking fb dev bus name in fb_is_primary_device().
>
> It seems that this bug reveals some bigger problem with to_pci_dev(),
> to_platform_device() and others, which just do container_of() and
> don't check whether struct device is a part of the appropriate structure.
> Should we do something more about it?
>
> KASan report:
>
> ==================================================================
> BUG: KASAN: slab-out-of-bounds in fb_is_primary_device+0x58/0x70 at addr ffff8803b68ca8a8
> Read of size 8 by task swapper/0/1
> =============================================================================
> BUG kmalloc-1024 (Not tainted): kasan: bad access detected
> -----------------------------------------------------------------------------
>
> Disabling lock debugging due to kernel taint
> INFO: Allocated in platform_device_alloc+0x2c/0xa0 age=183 cpu=0 pid=1
> ___slab_alloc+0x486/0x4e0
> __slab_alloc+0x20/0x40
> __kmalloc+0x1d7/0x240
> platform_device_alloc+0x2c/0xa0
> platform_device_register_full+0x3b/0x200
> sysfb_init+0xd4/0x11e
> do_one_initcall+0x122/0x290
> kernel_init_freeable+0x2e9/0x3ad
> kernel_init+0x13/0x100
> ret_from_fork+0x3f/0x70
> INFO: Slab 0xffffea000eda3200 objects=24 used=24 fp=0x (null) flags=0x5fff8000004080
> INFO: Object 0xffff8803b68ca450 @offset=9296 fp=0xffff8803b68ca760
>
> Bytes b4 ffff8803b68ca440: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca450: 60 a7 8c b6 03 88 ff ff 00 00 00 00 00 00 00 00 `...............
> Object ffff8803b68ca460: 20 6c 6f 82 ff ff ff ff 10 5d a8 b6 03 88 ff ff lo......]......
> Object ffff8803b68ca470: 00 60 b3 b8 00 88 ff ff 30 b1 c8 b9 03 88 ff ff .`......0.......
> Object ffff8803b68ca480: d0 e7 6d b7 03 88 ff ff 30 6c 6f 82 ff ff ff ff ..m.....0lo.....
> Object ffff8803b68ca490: 30 b1 c8 b9 03 88 ff ff 40 31 6f 82 ff ff ff ff 0.......@xxxxxxx
> Object ffff8803b68ca4a0: c0 a7 ad b6 03 88 ff ff 03 00 00 00 07 00 00 00 ................
> Object ffff8803b68ca4b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca4c0: 00 00 00 00 00 00 00 00 c8 a4 8c b6 03 88 ff ff ................
> Object ffff8803b68ca4d0: c8 a4 8c b6 03 88 ff ff 00 00 ca b7 03 88 ff ff ................
> Object ffff8803b68ca4e0: 00 00 00 00 00 00 00 00 60 6a 6f 82 ff ff ff ff ........`jo.....
> Object ffff8803b68ca4f0: 48 0b 68 82 ff ff ff ff 90 f5 4f b2 03 88 ff ff H.h.......O.....
> Object ffff8803b68ca500: 00 80 ea b0 03 88 ff ff 00 00 00 00 80 00 00 00 ................
> Object ffff8803b68ca510: 00 00 00 00 00 00 00 00 b8 d3 8c b6 03 88 ff ff ................
> Object ffff8803b68ca520: f8 d8 8c b6 03 88 ff ff ff ff ff 7f 00 00 00 00 ................
> Object ffff8803b68ca530: 00 00 00 00 00 00 00 00 38 a5 8c b6 03 88 ff ff ........8.......
> Object ffff8803b68ca540: 38 a5 8c b6 03 88 ff ff 00 00 00 00 00 00 00 00 8...............
> Object ffff8803b68ca550: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca560: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca570: e0 62 7c 81 ff ff ff ff 60 a4 8c b6 03 88 ff ff .b|.....`.......
> Object ffff8803b68ca580: 00 00 00 00 ff ff ff ff ff ff ff ff 00 00 00 00 ................
> Object ffff8803b68ca590: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca5a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca5b0: e0 ff ff ff 0f 00 00 00 b8 a5 8c b6 03 88 ff ff ................
> Object ffff8803b68ca5c0: b8 a5 8c b6 03 88 ff ff 70 69 7c 81 ff ff ff ff ........pi|.....
> Object ffff8803b68ca5d0: 00 00 00 00 00 00 00 00 d8 a5 8c b6 03 88 ff ff ................
> Object ffff8803b68ca5e0: d8 a5 8c b6 03 88 ff ff 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca5f0: 00 00 00 00 00 00 00 00 81 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca600: 02 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca610: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca620: 00 00 00 00 00 00 00 00 a0 7a fb ff 00 00 00 00 .........z......
> Object ffff8803b68ca630: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca640: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca650: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca660: 60 a6 8c b6 03 88 ff ff 60 a6 8c b6 03 88 ff ff `.......`.......
> Object ffff8803b68ca670: ff ff ff ff 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca690: 00 00 00 00 00 00 00 00 98 a6 8c b6 03 88 ff ff ................
> Object ffff8803b68ca6a0: 98 a6 8c b6 03 88 ff ff 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca6b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca6c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca6d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca6e0: e0 a6 8c b6 03 88 ff ff e0 a6 8c b6 03 88 ff ff ................
> Object ffff8803b68ca6f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca700: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca710: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca720: 30 8a 7b 81 ff ff ff ff 00 00 00 00 00 00 00 00 0.{.............
> Object ffff8803b68ca730: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca740: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca750: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca760: 65 66 69 2d 66 72 61 6d 65 62 75 66 66 65 72 00 efi-framebuffer.
> Object ffff8803b68ca770: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca790: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca7a0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca7b0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca7c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca7d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca7e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca7f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca810: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca820: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca830: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> Object ffff8803b68ca840: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
> CPU: 0 PID: 1 Comm: swapper/0 Tainted: G B 4.4.1 #10
> Hardware name: Gigabyte Technology Co., Ltd. To be filled by O.E.M./Q87M-D2H, BIOS F7 01/17/2014
> ffff8803b68c8000 00000000cdadd1cd ffff8803b7caf7c8 ffffffff815bab5c
> ffff8803b9c07180 ffff8803b7caf7f8 ffffffff8130fbf9 ffff8803b9c07180
> ffffea000eda3200 ffff8803b68ca450 1ffff10076f95f28 ffff8803b7caf820
> Call Trace:
> [<ffffffff815bab5c>] dump_stack+0x44/0x58
> [<ffffffff8130fbf9>] print_trailer+0xf9/0x150
> [<ffffffff813154e4>] object_err+0x34/0x40
> [<ffffffff81317bc1>] kasan_report_error+0x221/0x540
> [<ffffffff816878c9>] ? fb_alloc_cmap_gfp+0x139/0x190
> [<ffffffff8130f123>] ? set_track+0x83/0x140
> [<ffffffff81318478>] kasan_report+0x58/0x60
> [<ffffffff81a0a148>] ? fb_is_primary_device+0x58/0x70
> [<ffffffff81316d8d>] __asan_load8+0x5d/0x70
> [<ffffffff81a0a148>] fb_is_primary_device+0x58/0x70
> [<ffffffff8168505a>] register_framebuffer+0xda/0x5a0
> [<ffffffff816878c9>] ? fb_alloc_cmap_gfp+0x139/0x190
> [<ffffffff81684f80>] ? remove_conflicting_framebuffers+0x50/0x50
> [<ffffffff813172c6>] ? kasan_unpoison_shadow+0x36/0x50
> [<ffffffff813172c6>] ? kasan_unpoison_shadow+0x36/0x50
> [<ffffffff81317496>] ? memcpy+0x36/0x40
> [<ffffffff816874dc>] ? fb_copy_cmap+0x12c/0x190
> [<ffffffff8168787d>] ? fb_alloc_cmap_gfp+0xed/0x190
> [<ffffffff81693f1c>] efifb_probe+0xbac/0xc20
> [<ffffffff81693370>] ? efifb_setcolreg+0xe0/0xe0
> [<ffffffff8140ac15>] ? sysfs_do_create_link_sd.isra.2+0x85/0xc0
> [<ffffffff8169b543>] ? acpi_dev_pm_attach+0x2e/0xe2
> [<ffffffff817b9233>] platform_drv_probe+0x53/0xc0
> [<ffffffff817b5fd2>] driver_probe_device+0x2f2/0x6a0
> [<ffffffff817b6380>] ? driver_probe_device+0x6a0/0x6a0
> [<ffffffff817b6439>] __driver_attach+0xb9/0xc0
> [<ffffffff817b26b3>] bus_for_each_dev+0xf3/0x170
> [<ffffffff817b25c0>] ? subsys_dev_iter_exit+0x10/0x10
> [<ffffffff8131733e>] ? kasan_kmalloc+0x5e/0x70
> [<ffffffff815eadf4>] ? __list_add+0x74/0xf0
> [<ffffffff817b545b>] driver_attach+0x2b/0x30
> [<ffffffff817b4d17>] bus_add_driver+0x307/0x3d0
> [<ffffffff8290157c>] ? vesafb_driver_init+0x14/0x14
> [<ffffffff817b70a3>] driver_register+0xd3/0x190
> [<ffffffff817b910c>] __platform_driver_register+0x6c/0x80
> [<ffffffff8290158e>] efifb_driver_init+0x12/0x14
> [<ffffffff81002192>] do_one_initcall+0x122/0x290
> [<ffffffff81002070>] ? try_to_run_init_process+0x40/0x40
> [<ffffffff828a5a1b>] ? repair_env_string+0x2f/0x73
> [<ffffffff81118766>] ? parse_args+0x356/0x600
> [<ffffffff828a6584>] kernel_init_freeable+0x2e9/0x3ad
> [<ffffffff828a629b>] ? start_kernel+0x59a/0x59a
> [<ffffffff81098259>] ? native_load_sp0+0x29/0x40
> [<ffffffff8112812a>] ? finish_task_switch+0xaa/0x350
> [<ffffffff81c069f0>] ? rest_init+0x90/0x90
> [<ffffffff81c06a03>] kernel_init+0x13/0x100
> [<ffffffff81c069f0>] ? rest_init+0x90/0x90
> [<ffffffff81c1824f>] ret_from_fork+0x3f/0x70
> [<ffffffff81c069f0>] ? rest_init+0x90/0x90
>
> Memory state around the buggy address:
> ffff8803b68ca780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8803b68ca800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> >ffff8803b68ca880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ^
> ffff8803b68ca900: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8803b68ca980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> ==================================================================
>
> Signed-off-by: Alexander Popov <alpopov@xxxxxxxxxxxxxx>
> ---
> arch/x86/video/fbdev.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/video/fbdev.c b/arch/x86/video/fbdev.c
> index d5644bb..4999f78 100644
> --- a/arch/x86/video/fbdev.c
> +++ b/arch/x86/video/fbdev.c
> @@ -18,11 +18,12 @@ int fb_is_primary_device(struct fb_info *info)
> struct pci_dev *default_device = vga_default_device();
> struct resource *res = NULL;
>
> - if (device)
> - pci_dev = to_pci_dev(device);
> -
> - if (!pci_dev)
> + if (!device || !device->bus ||
> + !device->bus->name || strcmp(device->bus->name, "pci")) {
> return 0;
> + }
> +
> + pci_dev = to_pci_dev(device);
>
> if (default_device) {
> if (pci_dev == default_device)
> --
> 1.9.1
>

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