lib/cmdline: avoid page fault in next_arg

An argument list like "arg=val arg2 \"" can trigger a page fault if the
page pointed by 'args[0xffffffff]' is not mapped and potential memory
corruption otherwise (unlikely but possible if the bogus address is mapped
and contents happen to match the ascii value of the quote character).

The fix is to ensure that we load 'args[i-1]' only when (i > 0).

Prior to this commit the following command would trigger an
unhandled page fault in the kernel:

root@(none):/linus/fs/fat# insmod ./fat.ko "foo=bar \""
[ 33.870507] BUG: unable to handle page fault for address: ffff888204252608
[ 33.872180] #PF: supervisor read access in kernel mode
[ 33.873414] #PF: error_code(0x0000) - not-present page
[ 33.874650] PGD 4401067 P4D 4401067 PUD 0
[ 33.875321] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI
[ 33.876113] CPU: 16 PID: 399 Comm: insmod Not tainted 5.19.0-dbg-DEV #4
[ 33.877193] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-4 04/01/2014
[ 33.878739] RIP: 0010:next_arg+0xd1/0x110
[ 33.879399] Code: 22 75 1d 41 c6 04 01 00 41 80 f8 22 74 18 eb 35 4c 89 0e 45 31 d2 4c 89 cf 48 c7 02 00 00 00 00 41 80 f8 22 75 1f 41 8d 42 ff <41> 80 3c 01 22 75 14 41 c6 04 01 00 eb 0d 48 c7 02 00 00 00 00 41
[ 33.882338] RSP: 0018:ffffc90001253d08 EFLAGS: 00010246
[ 33.883174] RAX: 00000000ffffffff RBX: ffff888104252608 RCX: 0fc317bba1c1dd00
[ 33.884311] RDX: ffffc90001253d40 RSI: ffffc90001253d48 RDI: ffff888104252609
[ 33.885450] RBP: ffffc90001253d10 R08: 0000000000000022 R09: ffff888104252609
[ 33.886595] R10: 0000000000000000 R11: ffffffff82c7ff20 R12: 0000000000000282
[ 33.887748] R13: 00000000ffff8000 R14: 0000000000000000 R15: 0000000000007fff
[ 33.888887] FS: 00007f04ec7432c0(0000) GS:ffff88813d300000(0000) knlGS:0000000000000000
[ 33.890183] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 33.891111] CR2: ffff888204252608 CR3: 0000000100f36005 CR4: 0000000000170ee0
[ 33.892241] Call Trace:
[ 33.892641] <TASK>
[ 33.892989] parse_args+0x8f/0x220
[ 33.893538] load_module+0x138b/0x15a0
[ 33.894149] ? prepare_coming_module+0x50/0x50
[ 33.894879] ? kernel_read_file_from_fd+0x5f/0x90
[ 33.895639] __se_sys_finit_module+0xce/0x130
[ 33.896342] __x64_sys_finit_module+0x1d/0x20
[ 33.897042] do_syscall_64+0x44/0xa0
[ 33.897622] entry_SYSCALL_64_after_hwframe+0x63/0xcd
[ 33.898434] RIP: 0033:0x7f04ec85ef79
[ 33.899009] Code: 48 8d 3d da db 0d 00 0f 05 eb a5 66 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d c7 9e 0d 00 f7 d8 64 89 01 48
[ 33.901912] RSP: 002b:00007fffae81bfe8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
[ 33.903081] RAX: ffffffffffffffda RBX: 0000559c5f1d2640 RCX: 00007f04ec85ef79
[ 33.904191] RDX: 0000000000000000 RSI: 0000559c5f1d12a0 RDI: 0000000000000003
[ 33.905304] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
[ 33.906421] R10: 0000000000000003 R11: 0000000000000246 R12: 0000559c5f1d12a0
[ 33.907526] R13: 0000000000000000 R14: 0000559c5f1d25f0 R15: 0000559c5f1d12a0
[ 33.908631] </TASK>
[ 33.908986] Modules linked in: fat(+) [last unloaded: fat]
[ 33.909843] CR2: ffff888204252608
[ 33.910375] ---[ end trace 0000000000000000 ]---
[ 33.911172] RIP: 0010:next_arg+0xd1/0x110
[ 33.911796] Code: 22 75 1d 41 c6 04 01 00 41 80 f8 22 74 18 eb 35 4c 89 0e 45 31 d2 4c 89 cf 48 c7 02 00 00 00 00 41 80 f8 22 75 1f 41 8d 42 ff <41> 80 3c 01 22 75 14 41 c6 04 01 00 eb 0d 48 c7 02 00 00 00 00 41
[ 33.914643] RSP: 0018:ffffc90001253d08 EFLAGS: 00010246
[ 33.915446] RAX: 00000000ffffffff RBX: ffff888104252608 RCX: 0fc317bba1c1dd00
[ 33.916544] RDX: ffffc90001253d40 RSI: ffffc90001253d48 RDI: ffff888104252609
[ 33.917636] RBP: ffffc90001253d10 R08: 0000000000000022 R09: ffff888104252609
[ 33.918727] R10: 0000000000000000 R11: ffffffff82c7ff20 R12: 0000000000000282
[ 33.919821] R13: 00000000ffff8000 R14: 0000000000000000 R15: 0000000000007fff
[ 33.920908] FS: 00007f04ec7432c0(0000) GS:ffff88813d300000(0000) knlGS:0000000000000000
[ 33.922125] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 33.923017] CR2: ffff888204252608 CR3: 0000000100f36005 CR4: 0000000000170ee0
[ 33.924098] Kernel panic - not syncing: Fatal exception
[ 33.925776] Kernel Offset: disabled
[ 33.926347] Rebooting in 10 seconds..

Link: https://lkml.kernel.org/r/20220728232434.1666488-1-neelnatu@google.com
Signed-off-by: Neel Natu <neelnatu@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

lib/cmdline: Export next_arg() for being used in modules

At least one module will benefit from using next_arg() helper.
Let's export it for that module and others if they consider it
helpful.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

lib/cmdline: remove an unneeded local variable in next_arg()

The local variable 'next' is unneeded because you can simply advance the
existing pointer 'args'.

Link: https://lkml.kernel.org/r/20210201014707.3828753-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/cmdline: Allow get_options() to take 0 to validate the input

Allow get_options() to take 0 as a number of integers parameter to validate
the input.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

lib/cmdline: Update documentation to reflect behaviour

get_options() API has some tricks to optimize that may be not so obvious
to the caller. Update documentation to reflect current behaviour.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

lib/cmdline: allow NULL to be an output for get_option()

In the future we would like to use get_option() to only validate the
string and parse it separately. To achieve this, allow NULL to be an
output for get_option().

Link: https://lkml.kernel.org/r/20201112180732.75589-5-andriy.shevchenko@linux.intel.com
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Vitor Massaru Iha <vitor@massaru.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/cmdline: fix get_option() for strings starting with hyphen

When string doesn't have an integer and starts from hyphen get_option()
may return interesting results. Fix it to return 0.

The simple_strtoull() is used due to absence of simple_strtoul() in a boot
code on some architectures.

Note, the Fixes tag below is rather for anthropological curiosity.

Link: https://lkml.kernel.org/r/20201112180732.75589-4-andriy.shevchenko@linux.intel.com
Fixes: f68565831e72 ("Import 2.4.0-test2pre3")
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Cc: Shuah Khan <skhan@linuxfoundation.org>
Cc: Vitor Massaru Iha <vitor@massaru.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix multiple
warnings by explicitly adding multiple break statements instead of
letting the code fall through to the next case, and by replacing a
number of /* fall through */ comments with the new pseudo-keyword
macro fallthrough.

Notice that Clang doesn't recognize /* Fall through */ comments as
implicit fall-through markings.

Link: https://github.com/KSPP/linux/issues/115
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Revert "lib: Revert use of fallthrough pseudo-keyword in lib/"

This reverts commit 6a9dc5fd6170 ("lib: Revert use of fallthrough
pseudo-keyword in lib/")

Now that we can build arch/powerpc/boot/ free of -Wimplicit-fallthrough,
re-enable these fixes for lib/.

Signed-off-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Nathan Chancellor <natechancellor@gmail.com>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://github.com/ClangBuiltLinux/linux/issues/236
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

lib: Revert use of fallthrough pseudo-keyword in lib/

The following build error for powerpc64 was reported by Nathan Chancellor:

"$ scripts/config --file arch/powerpc/configs/powernv_defconfig -e KERNEL_XZ

$ make -skj"$(nproc)" ARCH=powerpc CROSS_COMPILE=powerpc64le-linux- distclean powernv_defconfig zImage
...
In file included from arch/powerpc/boot/../../../lib/decompress_unxz.c:234,
from arch/powerpc/boot/decompress.c:38:
arch/powerpc/boot/../../../lib/xz/xz_dec_stream.c: In function 'dec_main':
arch/powerpc/boot/../../../lib/xz/xz_dec_stream.c:586:4: error: 'fallthrough' undeclared (first use in this function)
586 | fallthrough;
| ^~~~~~~~~~~

This will end up affecting distribution configurations such as Debian
and OpenSUSE according to my testing. I am not sure what the solution
is, the PowerPC wrapper does not set -D__KERNEL__ so I am not sure
that compiler_attributes.h can be safely included."

In order to avoid these sort of problems, it seems that the best
solution is to use /* fall through */ comments instead of the
fallthrough pseudo-keyword macro in lib/, for now.

Reported-by: Nathan Chancellor <natechancellor@gmail.com>
Fixes: df561f6688fe ("treewide: Use fallthrough pseudo-keyword")
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Reviewed-and-tested-by: Nathan Chancellor <natechancellor@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

treewide: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 230

Based on 2 normalized pattern(s):

this source code is licensed under the gnu general public license
version 2 see the file copying for more details

this source code is licensed under general public license version 2
see

extracted by the scancode license scanner the SPDX license identifier

GPL-2.0-only

has been chosen to replace the boilerplate/reference in 52 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Enrico Weigelt <info@metux.net>
Reviewed-by: Allison Randal <allison@lohutok.net>
Reviewed-by: Alexios Zavras <alexios.zavras@intel.com>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190602204653.449021192@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

lib/cmdline.c: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch
cases where we are expecting to fall through.

This patch fixes the following warnings:

lib/cmdline.c:137:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
lib/cmdline.c:140:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
lib/cmdline.c:143:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
lib/cmdline.c:146:7: warning: this statement may fall through [-Wimplicit-fallthrough=]
lib/cmdline.c:149:7: warning: this statement may fall through [-Wimplicit-fallthrough=]

Warning level 3 was used: -Wimplicit-fallthrough=3

This patch is part of the ongoing efforts to enabling -Wimplicit-fallthrough.

Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>

lib/cmdline.c: remove meaningless comment

One line of code was commented out by c++ style comment for debugging, but
forgot removing it.

Clean it up.

Link: http://lkml.kernel.org/r/1503312113-11843-1-git-send-email-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/cmdline.c: fix get_options() overflow while parsing ranges

When using get_options() it's possible to specify a range of numbers,
like 1-100500. The problem is that it doesn't track array size while
calling internally to get_range() which iterates over the range and
fills the memory with numbers.

Link: http://lkml.kernel.org/r/2613C75C-B04D-4BFF-82A6-12F97BA0F620@gmail.com
Signed-off-by: Ilya V. Matveychikov <matvejchikov@gmail.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

boot/param: Move next_arg() function to lib/cmdline.c for later reuse

next_arg() will be used to parse boot parameters in the x86/boot/compressed code,
so move it to lib/cmdline.c for better code reuse.

No change in functionality.

Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Gustavo Padovan <gustavo.padovan@collabora.co.uk>
Cc: Jens Axboe <axboe@fb.com>
Cc: Jessica Yu <jeyu@redhat.com>
Cc: Johannes Berg <johannes.berg@intel.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Larry Finger <Larry.Finger@lwfinger.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dan.j.williams@intel.com
Cc: dave.jiang@intel.com
Cc: dyoung@redhat.com
Cc: keescook@chromium.org
Cc: zijun_hu <zijun_hu@htc.com>
Link: http://lkml.kernel.org/r/1492436099-4017-2-git-send-email-bhe@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

lib: Add a generic cmdline parse function parse_option_str

There should be a generic function to parse params like a=b,c
Adding parse_option_str in lib/cmdline.c which will return true
if there's specified option set in the params.

Also updated efi=old_map parsing code to use the new function

Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

lib/cmdline.c: add size unit t/p/e to memparse

For modern filesystems such as btrfs, t/p/e size level operations are
common. add size unit t/p/e parsing to memparse

Signed-off-by: Gui Hecheng <guihc.fnst@cn.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Satoru Takeuchi <takeuchi_satoru@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/cmdline.c: declare exported symbols immediately

WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
+EXPORT_SYMBOL(memparse);

WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
+EXPORT_SYMBOL(get_option);

WARNING: EXPORT_SYMBOL(foo); should immediately follow its function/variable
+EXPORT_SYMBOL(get_options);

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Cc: Levente Kurusa <levex@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/cmdline.c: fix style issues

WARNING: space prohibited between function name and open parenthesis '('
+int get_option (char **str, int *pint)

WARNING: space prohibited between function name and open parenthesis '('
+ *pint = simple_strtol (cur, str, 0);

ERROR: trailing whitespace
+ $

WARNING: please, no spaces at the start of a line
+ $

WARNING: space prohibited between function name and open parenthesis '('
+ res = get_option ((char **)&str, ints + i);

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib: reduce the use of module.h wherever possible

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include. Fix up any implicit
include dependencies that were being masked by module.h along
the way.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

generic, memparse(): constify argument

memparse()'s first argument can be const, so it should be.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

lib: allow memparse() to accept a NULL and ignorable second parm

Extend memparse() to allow the caller to use a NULL second parameter, which
would represent no interest in returning the address of the end of the parsed
string.

In numerous cases, callers invoke memparse() to parse a possibly-suffixed
string (such as "64K" or "2G" or whatever) and define a character pointer to
accept the end pointer being returned by memparse() even though they have no
interest in it and promptly throw it away.

This (backward-compatible) enhancement allows callers to use NULL in the cases
where they just don't care about getting back that end pointer.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] Numerous fixes to kernel-doc info in source files.

A variety of (mostly) innocuous fixes to the embedded kernel-doc content in
source files, including:

* make multi-line initial descriptions single line
* denote some function names, constants and structs as such
* change erroneous opening '/*' to '/**' in a few places
* reword some text for clarity

Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

[PATCH] get_options to allow a hypenated range for isolcpus

This allows a hyphenated range of positive numbers in the string passed
to command line helper function, get_options.

Currently the command line option "isolcpus=" takes as its argument a
list of cpus.

Format: <cpu number>,...,<cpu number>
Valid values of <cpu_number> include all cpus, 0 to "number of CPUs in
system - 1". This can get extremely long when isolating the majority of
cpus on a large system. The kernel isolcpus code would not need any
changing to use this feature. To use it, the change would be in the
command line format for 'isolcpus='
Format:
<cpu number>,...,<cpu number>
or
<cpu number>-<cpu number> (must be a positive range in ascending
order.)
or a mixture
<cpu number>,...,<cpu number>-<cpu number>

Signed-off-by: Derek Fults <dfults@sgi.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

Linux-2.6.12-rc2

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!