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Zack Rusin 91398b413d drm/vmwgfx: Keep a gem reference to user bos in surfaces
Surfaces can be backed (i.e. stored in) memory objects (mob's) which
are created and managed by the userspace as GEM buffers. Surfaces
grab only a ttm reference which means that the gem object can
be deleted underneath us, especially in cases where prime buffer
export is used.

Make sure that all userspace surfaces which are backed by gem objects
hold a gem reference to make sure they're not deleted before vmw
surfaces are done with them, which fixes:
------------[ cut here ]------------
refcount_t: underflow; use-after-free.
WARNING: CPU: 2 PID: 2632 at lib/refcount.c:28 refcount_warn_saturate+0xfb/0x150
Modules linked in: overlay vsock_loopback vmw_vsock_virtio_transport_common vmw_vsock_vmci_transport vsock snd_ens1371 snd_ac97_codec ac97_bus snd_pcm gameport>
CPU: 2 PID: 2632 Comm: vmw_ref_count Not tainted 6.5.0-rc2-vmwgfx #1
Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 11/12/2020
RIP: 0010:refcount_warn_saturate+0xfb/0x150
Code: eb 9e 0f b6 1d 8b 5b a6 01 80 fb 01 0f 87 ba e4 80 00 83 e3 01 75 89 48 c7 c7 c0 3c f9 a3 c6 05 6f 5b a6 01 01 e8 15 81 98 ff <0f> 0b e9 6f ff ff ff 0f b>
RSP: 0018:ffffbdc34344bba0 EFLAGS: 00010286
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000027
RDX: ffff960475ea1548 RSI: 0000000000000001 RDI: ffff960475ea1540
RBP: ffffbdc34344bba8 R08: 0000000000000003 R09: 65646e75203a745f
R10: ffffffffa5b32b20 R11: 72657466612d6573 R12: ffff96037d6a6400
R13: ffff9603484805b0 R14: 000000000000000b R15: ffff9603bed06060
FS:  00007f5fd8520c40(0000) GS:ffff960475e80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f5fda755000 CR3: 000000010d012005 CR4: 00000000003706e0
Call Trace:
 <TASK>
 ? show_regs+0x6e/0x80
 ? refcount_warn_saturate+0xfb/0x150
 ? __warn+0x91/0x150
 ? refcount_warn_saturate+0xfb/0x150
 ? report_bug+0x19d/0x1b0
 ? handle_bug+0x46/0x80
 ? exc_invalid_op+0x1d/0x80
 ? asm_exc_invalid_op+0x1f/0x30
 ? refcount_warn_saturate+0xfb/0x150
 drm_gem_object_handle_put_unlocked+0xba/0x110 [drm]
 drm_gem_object_release_handle+0x6e/0x80 [drm]
 drm_gem_handle_delete+0x6a/0xc0 [drm]
 ? __pfx_vmw_bo_unref_ioctl+0x10/0x10 [vmwgfx]
 vmw_bo_unref_ioctl+0x33/0x40 [vmwgfx]
 drm_ioctl_kernel+0xbc/0x160 [drm]
 drm_ioctl+0x2d2/0x580 [drm]
 ? __pfx_vmw_bo_unref_ioctl+0x10/0x10 [vmwgfx]
 ? do_vmi_munmap+0xee/0x180
 vmw_generic_ioctl+0xbd/0x180 [vmwgfx]
 vmw_unlocked_ioctl+0x19/0x20 [vmwgfx]
 __x64_sys_ioctl+0x99/0xd0
 do_syscall_64+0x5d/0x90
 ? syscall_exit_to_user_mode+0x2a/0x50
 ? do_syscall_64+0x6d/0x90
 ? handle_mm_fault+0x16e/0x2f0
 ? exit_to_user_mode_prepare+0x34/0x170
 ? irqentry_exit_to_user_mode+0xd/0x20
 ? irqentry_exit+0x3f/0x50
 ? exc_page_fault+0x8e/0x190
 entry_SYSCALL_64_after_hwframe+0x6e/0xd8
RIP: 0033:0x7f5fda51aaff
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 7>
RSP: 002b:00007ffd536a4d30 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffd536a4de0 RCX: 00007f5fda51aaff
RDX: 00007ffd536a4de0 RSI: 0000000040086442 RDI: 0000000000000003
RBP: 0000000040086442 R08: 000055fa603ada50 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000246 R12: 00007ffd536a51b8
R13: 0000000000000003 R14: 000055fa5ebb4c80 R15: 00007f5fda90f040
 </TASK>
---[ end trace 0000000000000000 ]---

A lot of the analyis on the bug was done by Murray McAllister and
Ian Forbes.

Reported-by: Murray McAllister <murray.mcallister@gmail.com>
Cc: Ian Forbes <iforbes@vmware.com>
Signed-off-by: Zack Rusin <zackr@vmware.com>
Fixes: a950b989ea ("drm/vmwgfx: Do not drop the reference to the handle too soon")
Cc: <stable@vger.kernel.org> # v6.2+
Reviewed-by: Martin Krastev <krastevm@vmware.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230928041355.737635-1-zack@kde.org
History 2023-10-09 15:53:30 -04:00
arch Fix preemption delays in the SGX code, remove unnecessarily UAPI-exported code, 2023-09-10 10:39:31 -07:00
block block: fix pin count management when merging same-page segments 2023-09-06 07:32:27 -06:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto This update includes the following changes: 2023-08-29 11:23:29 -07:00
Documentation drm ci for 6.6-rc1 2023-09-10 11:55:26 -07:00
drivers drm/vmwgfx: Keep a gem reference to user bos in surfaces 2023-10-09 15:53:30 -04:00
fs six smb3 client fixes, one fix for nls Kconfig, one minor spnego registry update 2023-09-09 19:56:23 -07:00
include dma-buf: add dma_fence_timestamp helper 2023-10-05 11:05:58 +02:00
init workqueue: Changes for v6.6 2023-09-01 16:06:32 -07:00
io_uring Revert "io_uring: fix IO hang in io_wq_put_and_exit from do_exit()" 2023-09-07 09:41:49 -06:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel RISC-V Patches for the 6.6 Merge Window, Part 2 (try 2) 2023-09-09 14:25:11 -07:00
lib iov_iter: Kunit tests for page extraction 2023-09-09 15:11:49 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm LoongArch changes for v6.6 2023-09-08 12:16:52 -07:00
net Including fixes from netfilter and bpf. 2023-09-07 18:33:07 -07:00
rust Documentation work keeps chugging along; stuff for 6.6 includes: 2023-08-30 20:05:42 -07:00
samples VFIO updates for v6.6-rc1 2023-08-30 20:36:01 -07:00
scripts Fix preemption delays in the SGX code, remove unnecessarily UAPI-exported code, 2023-09-10 10:39:31 -07:00
security Landlock updates for v6.6-rc1 2023-09-08 12:06:51 -07:00
sound sound fixes for 6.6-rc1 2023-09-08 13:07:50 -07:00
tools perf tools changes for v6.6: 2023-09-09 20:06:17 -07:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt ARM: 2023-09-07 13:52:20 -07:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap for-linus-2023083101 2023-09-01 12:31:44 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS drm ci for 6.6-rc1 2023-09-10 11:55:26 -07:00
Makefile Linux 6.6-rc1 2023-09-10 16:28:41 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.