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Vasily Averin 6c871b7314 pstore: pstore_ftrace_seq_next should increase position index 
In Aug 2018 NeilBrown noticed
commit 1f4aace60b ("fs/seq_file.c: simplify seq_file iteration code and interface")
"Some ->next functions do not increment *pos when they return NULL...
Note that such ->next functions are buggy and should be fixed.
A simple demonstration is

 dd if=/proc/swaps bs=1000 skip=1

Choose any block size larger than the size of /proc/swaps. This will
always show the whole last line of /proc/swaps"

/proc/swaps output was fixed recently, however there are lot of other
affected files, and one of them is related to pstore subsystem.

If .next function does not change position index, following .show function
will repeat output related to current position index.

There are at least 2 related problems:
- read after lseek beyond end of file, described above by NeilBrown
  "dd if=<AFFECTED_FILE> bs=1000 skip=1" will generate whole last list
- read after lseek on in middle of last line will output expected rest of
  last line but then repeat whole last line once again.

If .show() function generates multy-line output (like
pstore_ftrace_seq_show() does ?) following bash script cycles endlessly

 $ q=;while read -r r;do echo "$((++q)) $r";done < AFFECTED_FILE

Unfortunately I'm not familiar enough to pstore subsystem and was unable
to find affected pstore-related file on my test node.

If .next function does not change position index, following .show function
will repeat output related to current position index.

Cc: stable@vger.kernel.org
Fixes: 1f4aace60b ("fs/seq_file.c: simplify seq_file iteration code ...")
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206283
Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Link: https://lore.kernel.org/r/4e49830d-4c88-0171-ee24-1ee540028dad@virtuozzo.com
[kees: with robustness tweak from Joel Fernandes <joelaf@google.com>]
Signed-off-by: Kees Cook <keescook@chromium.org>
2020-02-27 08:04:59 -08:00
arch Bugfixes and improvements to selftests. On top of this, Mauro converted the 2020-02-16 13:01:42 -08:00
block block-5.6-2020-02-05 2020-02-06 06:15:23 +00:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto s390 updates for 5.6-rc2 2020-02-15 13:10:38 -08:00
Documentation Minor bug fixes for IPMI 2020-02-16 13:05:46 -08:00
drivers Minor bug fixes for IPMI 2020-02-16 13:05:46 -08:00
fs pstore: pstore_ftrace_seq_next should increase position index 2020-02-27 08:04:59 -08:00
include Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2020-02-15 12:51:22 -08:00
init Various fixes: 2020-02-11 16:39:18 -08:00
ipc proc: convert everything to "struct proc_ops" 2020-02-04 03:05:26 +00:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2020-02-15 12:51:22 -08:00
lib Various fixes: 2020-02-11 16:39:18 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'merge.nfs-fs_parse.1' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2020-02-08 13:26:41 -08:00
net NFS Client Bugfixes for Linux 5.6-rc2 2020-02-14 14:46:11 -08:00
samples Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
scripts kbuild: fix mismatch between .version and include/generated/compile.h 2020-02-11 05:18:40 +09:00
security selinux/stable-5.6 PR 20200210 2020-02-10 16:51:35 -08:00
sound ALSA: pcm: Fix double hw_free calls 2020-02-13 16:30:22 +01:00
tools Bugfixes and improvements to selftests. On top of this, Mauro converted the 2020-02-16 13:01:42 -08:00
usr Kbuild updates for v5.6 (2nd) 2020-02-09 16:05:50 -08:00
virt KVM: Disable preemption in kvm_get_running_vcpu() 2020-02-12 12:19:35 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap A handful of small documentation fixes that wandered in. 2020-02-07 13:03:10 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Sort entries in database for GPIO 2020-02-10 10:55:18 +01:00
Makefile Linux 5.6-rc2 2020-02-16 13:16:59 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.