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Nam Cao e3f0519da4 fbdev: fix incorrect address computation in deferred IO
commit 78d9161d2b upstream.

With deferred IO enabled, a page fault happens when data is written to the
framebuffer device. Then driver determines which page is being updated by
calculating the offset of the written virtual address within the virtual
memory area, and uses this offset to get the updated page within the
internal buffer. This page is later copied to hardware (thus the name
"deferred IO").

This offset calculation is only correct if the virtual memory area is
mapped to the beginning of the internal buffer. Otherwise this is wrong.
For example, if users do:
    mmap(ptr, 4096, PROT_WRITE, MAP_FIXED | MAP_SHARED, fd, 0xff000);

Then the virtual memory area will mapped at offset 0xff000 within the
internal buffer. This offset 0xff000 is not accounted for, and wrong page
is updated.

Correct the calculation by using vmf->pgoff instead. With this change, the
variable "offset" will no longer hold the exact offset value, but it is
rounded down to multiples of PAGE_SIZE. But this is still correct, because
this variable is only used to calculate the page offset.

Reported-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Closes: https://lore.kernel.org/linux-fbdev/271372d6-e665-4e7f-b088-dee5f4ab341a@oracle.com
Fixes: 56c134f7f1 ("fbdev: Track deferred-I/O pages in pageref struct")
Cc: <stable@vger.kernel.org>
Signed-off-by: Nam Cao <namcao@linutronix.de>
Reviewed-by: Thomas Zimmermann <tzimmermann@suse.de>
Tested-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com>
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20240423115053.4490-1-namcao@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2024-05-02 16:29:30 +02:00
arch arm64: dts: rockchip: enable internal pull-up for Q7_THRM# on RK3399 Puma 2024-05-02 16:29:29 +02:00
block block: prevent division by zero in blk_rq_stat_sum() 2024-04-13 13:05:12 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto Revert "crypto: api - Disallow identical driver names" 2024-05-02 16:29:27 +02:00
Documentation net: make SK_MEMORY_PCPU_RESERV tunable 2024-05-02 16:29:24 +02:00
drivers fbdev: fix incorrect address computation in deferred IO 2024-05-02 16:29:30 +02:00
fs btrfs: fix information leak in btrfs_ioctl_logical_to_ino() 2024-05-02 16:29:28 +02:00
include ethernet: Add helper for assigning packet type when dest address does not match device address 2024-05-02 16:29:29 +02:00
init rust: make mutually exclusive with CFI_CLANG 2024-05-02 16:29:27 +02:00
io_uring io_uring: Fix io_cqring_wait() not restoring sigmask on get_timespec64() failure 2024-04-27 17:07:04 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel cpu: Re-enable CPU mitigations by default for !X86 architectures 2024-05-02 16:29:28 +02:00
lib stackdepot: respect __GFP_NOLOCKDEP allocation flag 2024-05-02 16:29:29 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm/memory-failure: fix deadlock when hugetlb_optimize_vmemmap is enabled 2024-04-27 17:07:16 +02:00
net ethernet: Add helper for assigning packet type when dest address does not match device address 2024-05-02 16:29:29 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:12:28 +01:00
scripts gcc-plugins/stackleak: Avoid .head.text section 2024-04-13 13:05:23 +02:00
security landlock: Warn once if a Landlock action is requested while disabled 2024-04-03 15:19:32 +02:00
sound Revert "ASoC: ti: Convert Pandora ASoC to GPIO descriptors" 2024-04-29 12:32:48 +02:00
tools selftests/ftrace: Limit length in subsystem-enable tests 2024-04-27 17:07:04 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt KVM: Always flush async #PF workqueue when vCPU is being destroyed 2024-04-03 15:19:25 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
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 ALSA: scarlett2: Rename scarlett_gen2 to scarlett2 2024-04-27 17:07:11 +02:00
Makefile Linux 6.1.89 2024-04-29 12:32:48 +02:00
README

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

There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
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    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.