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Filename Latest commit message Latest commit date
Mazin Rezk f1b4bdde2b drm/amd/display: Clear dm_state for fast updates
commit fde9f39ac7f1ffd799a96ffa1e06b2051f0898f1 upstream.

This patch fixes a race condition that causes a use-after-free during
amdgpu_dm_atomic_commit_tail. This can occur when 2 non-blocking commits
are requested and the second one finishes before the first. Essentially,
this bug occurs when the following sequence of events happens:

1. Non-blocking commit #1 is requested w/ a new dm_state #1 and is
deferred to the workqueue.

2. Non-blocking commit #2 is requested w/ a new dm_state #2 and is
deferred to the workqueue.

3. Commit #2 starts before commit #1, dm_state #1 is used in the
commit_tail and commit #2 completes, freeing dm_state #1.

4. Commit #1 starts after commit #2 completes, uses the freed dm_state
1 and dereferences a freelist pointer while setting the context.

Since this bug has only been spotted with fast commits, this patch fixes
the bug by clearing the dm_state instead of using the old dc_state for
fast updates. In addition, since dm_state is only used for its dc_state
and amdgpu_dm_atomic_commit_tail will retain the dc_state if none is found,
removing the dm_state should not have any consequences in fast updates.

This use-after-free bug has existed for a while now, but only caused a
noticeable issue starting from 5.7-rc1 due to 3202fa62f ("slub: relocate
freelist pointer to middle of object") moving the freelist pointer from
dm_state->base (which was unused) to dm_state->context (which is
dereferenced).

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=207383
Fixes: bd200d190f ("drm/amd/display: Don't replace the dc_state for fast updates")
Reported-by: Duncan <1i5t5.duncan@cox.net>
Signed-off-by: Mazin Rezk <mnrzk@protonmail.com>
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-05 09:59:43 +02:00
arch ARM: dts: imx6qdl-icore: Fix OTG_ID pin and sdcard detect 2020-08-05 09:59:43 +02:00
block block: fix get_max_segment_size() overflow on 32bit arch 2020-07-22 09:33:17 +02:00
certs
crypto keys: asymmetric: fix error return code in software_key_query() 2020-07-22 09:33:04 +02:00
Documentation doc: dt: bindings: usb: dwc3: Update entries for disabling SS instances in park mode 2020-07-22 09:32:59 +02:00
drivers drm/amd/display: Clear dm_state for fast updates 2020-08-05 09:59:43 +02:00
fs Revert "cifs: Fix the target file was deleted when rename failed." 2020-07-29 10:18:41 +02:00
include wireless: Use offsetof instead of custom macro. 2020-08-05 09:59:42 +02:00
init x86: Fix early boot crash on gcc-10, third try 2020-05-20 08:20:34 +02:00
ipc ipc/util.c: sysvipc_find_ipc() incorrectly updates position index 2020-05-20 08:20:16 +02:00
kernel uprobes: Change handle_swbp() to send SIGTRAP with si_code=SI_KERNEL, to fix GDB regression 2020-07-29 10:18:29 +02:00
lib test_objagg: Fix potential memory leak in error handling 2020-06-30 15:37:04 -04:00
LICENSES
mm mm/filemap.c: don't bother dropping mmap_sem for zero size readahead 2020-08-05 09:59:41 +02:00
net 9p/trans_fd: Fix concurrency del of req_list in p9_fd_cancelled/p9_read_work 2020-08-05 09:59:42 +02:00
samples samples/vfs: avoid warning in statx override 2020-07-09 09:37:54 +02:00
scripts scripts/gdb: fix lx-symbols 'gdb.error' while loading modules 2020-07-29 10:18:35 +02:00
security apparmor: ensure that dfa state tables have entries 2020-07-22 09:33:05 +02:00
sound ALSA: hda/hdmi: Fix keep_power assignment for non-component devices 2020-08-05 09:59:42 +02:00
tools perf stat: Zero all the 'ena' and 'run' array slot stats for interval mode 2020-07-22 09:33:05 +02:00
usr
virt KVM: arm64: Save the host's PtrAuth keys in non-preemptible context 2020-06-17 16:40:38 +02:00
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Makefile Linux 5.4.55 2020-07-31 18:39:32 +02:00
README

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.