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A mirror of the official Linux kernel repository just in case
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Sebastian Mayr 9212ec7d83 uprobes/x86: Fix detection of 32-bit user mode 
32-bit processes running on a 64-bit kernel are not always detected
correctly, causing the process to crash when uretprobes are installed.

The reason for the crash is that in_ia32_syscall() is used to determine the
process's mode, which only works correctly when called from a syscall.

In the case of uretprobes, however, the function is called from a exception
and always returns 'false' on a 64-bit kernel. In consequence this leads to
corruption of the process's return address.

Fix this by using user_64bit_mode() instead of in_ia32_syscall(), which
is correct in any situation.

[ tglx: Add a comment and the following historical info ]

This should have been detected by the rename which happened in commit

  abfb9498ee ("x86/entry: Rename is_{ia32,x32}_task() to in_{ia32,x32}_syscall()")

which states in the changelog:

    The is_ia32_task()/is_x32_task() function names are a big misnomer: they
    suggests that the compat-ness of a system call is a task property, which
    is not true, the compatness of a system call purely depends on how it
    was invoked through the system call layer.
    .....

and then it went and blindly renamed every call site.

Sadly enough this was already mentioned here:

   8faaed1b9f ("uprobes/x86: Introduce sizeof_long(), cleanup adjust_ret_addr() and
arch_uretprobe_hijack_return_addr()")

where the changelog says:

    TODO: is_ia32_task() is not what we actually want, TS_COMPAT does
    not necessarily mean 32bit. Fortunately syscall-like insns can't be
    probed so it actually works, but it would be better to rename and
    use is_ia32_frame().

and goes all the way back to:

    0326f5a94d ("uprobes/core: Handle breakpoint and singlestep exceptions")

Oh well. 7+ years until someone actually tried a uretprobe on a 32bit
process on a 64bit kernel....

Fixes: 0326f5a94d ("uprobes/core: Handle breakpoint and singlestep exceptions")
Signed-off-by: Sebastian Mayr <me@sam.st>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Dmitry Safonov <dsafonov@virtuozzo.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20190728152617.7308-1-me@sam.st
2019-08-26 15:55:09 +02:00
arch uprobes/x86: Fix detection of 32-bit user mode 2019-08-26 15:55:09 +02:00
block block, bfq: handle NULL return value by bfq_init_rq() 2019-08-08 07:31:50 -06:00
certs Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
crypto USB / PHY patches for 5.3-rc1 2019-07-11 15:40:06 -07:00
Documentation x86/CPU/AMD: Clear RDRAND CPUID bit on AMD family 15h/16h 2019-08-19 19:42:52 +02:00
drivers Bug fix for NTB MSI kernel compile warning 2019-08-11 10:13:53 -07:00
fs dax fixes v5.3-rc4 2019-08-11 13:15:10 -07:00
include Bugfixes (arm and x86) and cleanups. 2019-08-09 15:46:29 -07:00
init Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
ipc Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 15:48:02 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-06 17:11:59 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/memremap: Fix reuse of pgmap instances with internal references 2019-08-09 14:16:15 -07:00
net net: dsa: sja1105: Fix memory leak on meta state machine error path 2019-08-06 14:37:02 -07:00
samples treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again 2019-07-25 11:05:10 +02:00
scripts kbuild: show hint if subdir-y/m is used to visit module Makefile 2019-08-10 01:45:31 +09:00
security selinux/stable-5.3 PR 20190801 2019-08-02 18:40:49 -07:00
sound sound fixes for 5.3-rc4 2019-08-09 09:21:27 -07:00
tools Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 16:19:02 -07:00
usr kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test 2019-07-23 10:45:46 +02:00
virt KVM/arm fixes for 5.3, take #2 2019-08-09 16:53:50 +02:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: Add compilation database file 2019-07-27 12:18:19 +09:00
.mailmap MAINTAINERS: Update my email address 2019-07-22 14:57:50 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Remove references to dead website. 2019-07-19 12:22:04 -07:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS, x86/CPU: Tony Luck will maintain asm/intel-family.h 2019-08-15 09:54:05 +02:00
Makefile Linux 5.3-rc4 2019-08-11 13:26:41 -07:00
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.