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Gao Xiang 1fa7c9b422 staging: erofs: fix illegal address access under memory pressure 
commit 1e5ceeab69 upstream.

Considering a read request with two decompressed file pages,
If a decompression work cannot be started on the previous page
due to memory pressure but in-memory LTP map lookup is done,
builder->work should be still NULL.

Moreover, if the current page also belongs to the same map,
it won't try to start the decompression work again and then
run into trouble.

This patch aims to solve the above issue only with little changes
as much as possible in order to make the fix backport easier.

kernel message is:
<4>[1051408.015930s]SLUB: Unable to allocate memory on node -1, gfp=0x2408040(GFP_NOFS|__GFP_ZERO)
<4>[1051408.015930s]  cache: erofs_compress, object size: 144, buffer size: 144, default order: 0, min order: 0
<4>[1051408.015930s]  node 0: slabs: 98, objs: 2744, free: 0
  * Cannot allocate the decompression work

<3>[1051408.015960s]erofs: z_erofs_vle_normalaccess_readpages, readahead error at page 1008 of nid 5391488
  * Note that the previous page was failed to read

<0>[1051408.015960s]Internal error: Accessing user space memory outside uaccess.h routines: 96000005 [#1] PREEMPT SMP
...
<4>[1051408.015991s]Hardware name: kirin710 (DT)
...
<4>[1051408.016021s]PC is at z_erofs_vle_work_add_page+0xa0/0x17c
<4>[1051408.016021s]LR is at z_erofs_do_read_page+0x12c/0xcf0
...
<4>[1051408.018096s][<ffffff80c6fb0fd4>] z_erofs_vle_work_add_page+0xa0/0x17c
<4>[1051408.018096s][<ffffff80c6fb3814>] z_erofs_vle_normalaccess_readpages+0x1a0/0x37c
<4>[1051408.018096s][<ffffff80c6d670b8>] read_pages+0x70/0x190
<4>[1051408.018127s][<ffffff80c6d6736c>] __do_page_cache_readahead+0x194/0x1a8
<4>[1051408.018127s][<ffffff80c6d59318>] filemap_fault+0x398/0x684
<4>[1051408.018127s][<ffffff80c6d8a9e0>] __do_fault+0x8c/0x138
<4>[1051408.018127s][<ffffff80c6d8f90c>] handle_pte_fault+0x730/0xb7c
<4>[1051408.018127s][<ffffff80c6d8fe04>] __handle_mm_fault+0xac/0xf4
<4>[1051408.018157s][<ffffff80c6d8fec8>] handle_mm_fault+0x7c/0x118
<4>[1051408.018157s][<ffffff80c8c52998>] do_page_fault+0x354/0x474
<4>[1051408.018157s][<ffffff80c8c52af8>] do_translation_fault+0x40/0x48
<4>[1051408.018157s][<ffffff80c6c002f4>] do_mem_abort+0x80/0x100
<4>[1051408.018310s]---[ end trace 9f4009a3283bd78b ]---

Fixes: 3883a79abd ("staging: erofs: introduce VLE decompression support")
Cc: <stable@vger.kernel.org> # 4.19+
Signed-off-by: Gao Xiang <gaoxiang25@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-03-10 07:17:15 +01:00
arch x86/uaccess: Don't leak the AC flag into __put_user() value evaluation 2019-03-05 17:58:54 +01:00
block
certs
crypto
Documentation
drivers staging: erofs: fix illegal address access under memory pressure 2019-03-10 07:17:15 +01:00
firmware
fs hugetlbfs: fix races and page leaks during migration 2019-03-05 17:58:53 +01:00
include cpufreq: Use struct kobj_attribute instead of struct global_attr 2019-03-10 07:17:15 +01:00
init
ipc
kernel locking/rwsem: Fix (possible) missed wakeup 2019-03-05 17:58:49 +01:00
lib
LICENSES
mm hugetlbfs: fix races and page leaks during migration 2019-03-05 17:58:53 +01:00
net cfg80211: extend range deviation for DMG 2019-03-05 17:58:52 +01:00
samples
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security
sound
tools kvm: selftests: Fix region overlap check in kvm_util 2019-03-05 17:58:52 +01:00
usr
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Makefile Linux 4.19.27 2019-03-05 17:58:54 +01:00
README

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.