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Commit Graph

26 Commits

Author SHA1 Message Date
Guenter Roeck
0cc011c576 lib/list_debug.c: Detect uninitialized lists
In some circumstances, attempts are made to add entries to or to remove
entries from an uninitialized list.  A prime example is
amdgpu_bo_vm_destroy(): It is indirectly called from
ttm_bo_init_reserved() if that function fails, and tries to remove an
entry from a list.  However, that list is only initialized in
amdgpu_bo_create_vm() after the call to ttm_bo_init_reserved() returned
success.  This results in crashes such as

 BUG: kernel NULL pointer dereference, address: 0000000000000000
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 0 P4D 0
 Oops: 0000 [] PREEMPT SMP NOPTI
 CPU: 1 PID: 1479 Comm: chrome Not tainted 5.10.110-15768-g29a72e65dae5
 Hardware name: Google Grunt/Grunt, BIOS Google_Grunt.11031.149.0 07/15/2020
 RIP: 0010:__list_del_entry_valid+0x26/0x7d
 ...
 Call Trace:
  amdgpu_bo_vm_destroy+0x48/0x8b
  ttm_bo_init_reserved+0x1d7/0x1e0
  amdgpu_bo_create+0x212/0x476
  ? amdgpu_bo_user_destroy+0x23/0x23
  ? kmem_cache_alloc+0x60/0x271
  amdgpu_bo_create_vm+0x40/0x7d
  amdgpu_vm_pt_create+0xe8/0x24b
 ...

Check if the list's prev and next pointers are NULL to catch such problems.

Link: https://lkml.kernel.org/r/20220531222951.92073-1-linux@roeck-us.net
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-06-16 19:58:20 -07:00
Zhen Lei
a31f9336ed lib/list_debug.c: print more list debugging context in __list_del_entry_valid()
Currently, the entry->prev and entry->next are considered to be valid as
long as they are not LIST_POISON{1|2}.  However, the memory may be
corrupted.  The prev->next is invalid probably because 'prev' is
invalid, not because prev->next's content is illegal.

Unfortunately, the printk and its subfunctions will modify the registers
that hold the 'prev' and 'next', and we don't see this valuable
information in the BUG context.

So print the contents of 'entry->prev' and 'entry->next'.

Here's an example:
  list_del corruption. prev->next should be c0ecbf74, but was c08410dc
  kernel BUG at lib/list_debug.c:53!
  ... ...
  PC is at __list_del_entry_valid+0x58/0x98
  LR is at __list_del_entry_valid+0x58/0x98
  psr: 60000093
  sp : c0ecbf30  ip : 00000000  fp : 00000001
  r10: c08410d0  r9 : 00000001  r8 : c0825e0c
  r7 : 20000013  r6 : c08410d0  r5 : c0ecbf74  r4 : c0ecbf74
  r3 : c0825d08  r2 : 00000000  r1 : df7ce6f4  r0 : 00000044
  ... ...
  Stack: (0xc0ecbf30 to 0xc0ecc000)
  bf20:                                     c0ecbf74 c0164fd0 c0ecbf70 c0165170
  bf40: c0eca000 c0840c00 c0840c00 c0824500 c0825e0c c0189bbc c088f404 60000013
  bf60: 60000013 c0e85100 000004ec 00000000 c0ebcdc0 c0ecbf74 c0ecbf74 c0825d08
  bf80: c0e807c0 c018965c 00000000 c013f2a0 c0e807c0 c013f154 00000000 00000000
  bfa0: 00000000 00000000 00000000 c01001b0 00000000 00000000 00000000 00000000
  bfc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
  bfe0: 00000000 00000000 00000000 00000000 00000013 00000000 00000000 00000000
  (__list_del_entry_valid) from (__list_del_entry+0xc/0x20)
  (__list_del_entry) from (finish_swait+0x60/0x7c)
  (finish_swait) from (rcu_gp_kthread+0x560/0xa20)
  (rcu_gp_kthread) from (kthread+0x14c/0x15c)
  (kthread) from (ret_from_fork+0x14/0x24)

At first, I thought prev->next was overwritten.  Later, I carefully
analyzed the RCU code and the disassembly code.  The error occurred when
deleting a node from the list rcu_state.gp_wq.  The System.map shows
that the address of rcu_state is c0840c00.  Then I use gdb to obtain the
offset of rcu_state.gp_wq.task_list.

  (gdb) p &((struct rcu_state *)0)->gp_wq.task_list
  $1 = (struct list_head *) 0x4dc

Again:
  list_del corruption. prev->next should be c0ecbf74, but was c08410dc

  c08410dc = c0840c00 + 0x4dc = &rcu_state.gp_wq.task_list

Because rcu_state.gp_wq has at most one node, so I can guess that "prev
= &rcu_state.gp_wq.task_list".  But for other scenes, maybe I wasn't so
lucky, I cannot figure out the value of 'prev'.

Link: https://lkml.kernel.org/r/20211207025835.1909-1-thunder.leizhen@huawei.com
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Cc: "Paul E . McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-01-20 08:52:53 +02:00
Matthew Wilcox
68c1f08203 lib/list_debug.c: print unmangled addresses
The entire point of printing the pointers in list_debug is to see if
there's any useful information in them (eg poison values, ASCII, etc);
obscuring them to see if they compare equal makes them much less useful.
If an attacker can force this message to be printed, we've already lost.

Link: http://lkml.kernel.org/r/20180401223237.GV13332@bombadil.infradead.org
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Tobin C. Harding <me@tobin.cc>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-04-11 10:28:35 -07:00
Kees Cook
85caa95b9f bug: switch data corruption check to __must_check
The CHECK_DATA_CORRUPTION() macro was designed to have callers do
something meaningful/protective on failure.  However, using "return
false" in the macro too strictly limits the design patterns of callers.
Instead, let callers handle the logic test directly, but make sure that
the result IS checked by forcing __must_check (which appears to not be
able to be used directly on macro expressions).

Link: http://lkml.kernel.org/r/20170206204547.GA125312@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Suggested-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-02-24 17:46:56 -08:00
Kees Cook
de54ebbe26 bug: Provide toggle for BUG on data corruption
The kernel checks for cases of data structure corruption under some
CONFIGs (e.g. CONFIG_DEBUG_LIST). When corruption is detected, some
systems may want to BUG() immediately instead of letting the system run
with known corruption.  Usually these kinds of manipulation primitives can
be used by security flaws to gain arbitrary memory write control. This
provides a new config CONFIG_BUG_ON_DATA_CORRUPTION and a corresponding
macro CHECK_DATA_CORRUPTION for handling these situations. Notably, even
if not BUGing, the kernel should not continue processing the corrupted
structure.

This is inspired by similar hardening by Syed Rameez Mustafa in MSM
kernels, and in PaX and Grsecurity, which is likely in response to earlier
removal of the BUG calls in commit 924d9addb9 ("list debugging: use
WARN() instead of BUG()").

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
2016-10-31 13:01:58 -07:00
Kees Cook
0cd340dcb0 list: Split list_del() debug checking into separate function
Similar to the list_add() debug consolidation, this commit consolidates
the debug checking performed during CONFIG_DEBUG_LIST into a new
__list_del_entry_valid() function, and stops list updates when corruption
is found.

Refactored from same hardening in PaX and Grsecurity.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
2016-10-31 13:01:57 -07:00
Kees Cook
54acd4397d rculist: Consolidate DEBUG_LIST for list_add_rcu()
This commit consolidates the debug checking for list_add_rcu() into the
new single __list_add_valid() debug function.  Notably, this commit fixes
the sanity check that was added in commit 17a801f4bf ("list_debug:
WARN for adding something already in the list"), which wasn't checking
RCU-protected lists.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
2016-10-31 13:01:57 -07:00
Kees Cook
d7c816733d list: Split list_add() debug checking into separate function
Right now, __list_add() code is repeated either in list.h or in
list_debug.c, but the only differences between the two versions
are the debug checks. This commit therefore extracts these debug
checks into a separate __list_add_valid() function and consolidates
__list_add(). Additionally this new __list_add_valid() function will stop
list manipulations if a corruption is detected, instead of allowing for
further corruption that may lead to even worse conditions.

This is slight refactoring of the same hardening done in PaX and Grsecurity.

Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Rik van Riel <riel@redhat.com>
2016-10-31 13:01:56 -07:00
Dan Williams
d77a117e68 list: kill list_force_poison()
Given we have uninitialized list_heads being passed to list_add() it
will always be the case that those uninitialized values randomly trigger
the poison value.  Especially since a list_add() operation will seed the
stack with the poison value for later stack allocations to trip over.

For example, see these two false positive reports:

  list_add attempted on force-poisoned entry
  WARNING: at lib/list_debug.c:34
  [..]
  NIP [c00000000043c390] __list_add+0xb0/0x150
  LR [c00000000043c38c] __list_add+0xac/0x150
  Call Trace:
    __list_add+0xac/0x150 (unreliable)
    __down+0x4c/0xf8
    down+0x68/0x70
    xfs_buf_lock+0x4c/0x150 [xfs]

  list_add attempted on force-poisoned entry(0000000000000500),
   new->next == d0000000059ecdb0, new->prev == 0000000000000500
  WARNING: at lib/list_debug.c:33
  [..]
  NIP [c00000000042db78] __list_add+0xa8/0x140
  LR [c00000000042db74] __list_add+0xa4/0x140
  Call Trace:
    __list_add+0xa4/0x140 (unreliable)
    rwsem_down_read_failed+0x6c/0x1a0
    down_read+0x58/0x60
    xfs_log_commit_cil+0x7c/0x600 [xfs]

Fixes: commit 5c2c2587b1 ("mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup")
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Reported-by: Eryu Guan <eguan@redhat.com>
Tested-by: Eryu Guan <eguan@redhat.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-03-09 15:43:42 -08:00
Dan Williams
5c2c2587b1 mm, dax, pmem: introduce {get|put}_dev_pagemap() for dax-gup
get_dev_page() enables paths like get_user_pages() to pin a dynamically
mapped pfn-range (devm_memremap_pages()) while the resulting struct page
objects are in use.  Unlike get_page() it may fail if the device is, or
is in the process of being, disabled.  While the initial lookup of the
range may be an expensive list walk, the result is cached to speed up
subsequent lookups which are likely to be in the same mapped range.

devm_memremap_pages() now requires a reference counter to be specified
at init time.  For pmem this means moving request_queue allocation into
pmem_alloc() so the existing queue usage counter can track "device
pages".

ZONE_DEVICE pages always have an elevated count and will never be on an
lru reclaim list.  That space in 'struct page' can be redirected for
other uses, but for safety introduce a poison value that will always
trip __list_add() to assert.  This allows half of the struct list_head
storage to be reclaimed with some assurance to back up the assumption
that the page count never goes to zero and a list_add() is never
attempted.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Tested-by: Logan Gunthorpe <logang@deltatee.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-01-15 17:56:32 -08:00
Paul E. McKenney
1c97be677f list: Use WRITE_ONCE() when adding to lists and hlists
Code that does lockless emptiness testing of non-RCU lists is relying
on the list-addition code to write the list head's ->next pointer
atomically.  This commit therefore adds WRITE_ONCE() to list-addition
pointer stores that could affect the head's ->next pointer.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-11-23 10:37:35 -08:00
Paul E. McKenney
5cf05ad758 rcu: Fix broken strings in RCU's source code.
Although the C language allows you to break strings across lines, doing
this makes it hard for people to find the Linux kernel code corresponding
to a given console message.  This commit therefore fixes broken strings
throughout RCU's source code.

Suggested-by: Josh Triplett <josh@joshtriplett.org>
Suggested-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-07-06 06:01:49 -07:00
Chris Metcalf
17a801f4bf list_debug: WARN for adding something already in the list
We were bitten by this at one point and added an additional sanity test
for DEBUG_LIST.  You can't validly add a list_head to a list where either
prev or next is the same as the thing you're adding.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2012-05-29 16:22:32 -07:00
Dave Jones
559f9badd1 rcu: List-debug variants of rcu list routines.
* Make __list_add_rcu check the next->prev and prev->next pointers
  just like __list_add does.
* Make list_del_rcu use __list_del_entry, which does the same checking
  at deletion time.

Has been running for a week here without anything being tripped up,
but it seems worth adding for completeness just in case something
ever does corrupt those lists.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-04-24 20:54:49 -07:00
Linus Torvalds
11bcb32848 The following text was taken from the original review request:
"[PATCH 0/3] RFC - module.h usage cleanups in fs/ and lib/"
 		https://lkml.org/lkml/2012/2/29/589
 --
 
 Fix up files in fs/ and lib/ dirs to only use module.h if they really
 need it.
 
 These are trivial in scope vs. the work done previously.  We now have
 things where any few remaining cleanups can be farmed out to arch or
 subsystem maintainers, and I have done so when possible.  What is
 remaining here represents the bits that don't clearly lie within a
 single arch/subsystem boundary, like the fs dir and the lib dir.
 
 Some duplicate includes arising from overlapping fixes from
 independent subsystem maintainer submissions are also quashed.
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Merge tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux

Pull cleanup of fs/ and lib/ users of module.h from Paul Gortmaker:
 "Fix up files in fs/ and lib/ dirs to only use module.h if they really
  need it.

  These are trivial in scope vs the work done previously.  We now have
  things where any few remaining cleanups can be farmed out to arch or
  subsystem maintainers, and I have done so when possible.  What is
  remaining here represents the bits that don't clearly lie within a
  single arch/subsystem boundary, like the fs dir and the lib dir.

  Some duplicate includes arising from overlapping fixes from
  independent subsystem maintainer submissions are also quashed."

Fix up trivial conflicts due to clashes with other include file cleanups
(including some due to the previous bug.h cleanup pull).

* tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
  lib: reduce the use of module.h wherever possible
  fs: reduce the use of module.h wherever possible
  includecheck: delete any duplicate instances of module.h
2012-03-24 10:24:31 -07:00
Paul Gortmaker
8bc3bcc93a 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>
2012-03-07 15:04:04 -05:00
Paul Gortmaker
50af5ead3b bug.h: add include of it to various implicit C users
With bug.h currently living right in linux/kernel.h there
are files that use BUG_ON and friends but are not including
the header explicitly.  Fix them up so we can remove the
presence in kernel.h file.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-02-29 17:15:08 -05:00
Paul Gortmaker
b116ee4d77 lib: fix implicit users of kernel.h for TAINT_WARN
A pending header cleanup will cause this to show up as:

lib/average.c:38: error: 'TAINT_WARN' undeclared (first use in this function)
lib/list_debug.c:24: error: 'TAINT_WARN' undeclared (first use in this function)

and TAINT_WARN comes from include/linux/kernel.h file.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
2012-02-28 17:49:27 -05:00
Linus Torvalds
3c18d4de86 Expand CONFIG_DEBUG_LIST to several other list operations
When list debugging is enabled, we aim to readably show list corruption
errors, and the basic list_add/list_del operations end up having extra
debugging code in them to do some basic validation of the list entries.

However, "list_del_init()" and "list_move[_tail]()" ended up avoiding
the debug code due to how they were written. This fixes that.

So the _next_ time we have list_move() problems with stale list entries,
we'll hopefully have an easier time finding them..

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-02-18 11:32:28 -08:00
Baruch Siach
e3f76e3386 list debugging: warn when deleting a deleted entry
Use the magic LIST_POISON* values to detect an incorrect use of list_del
on a deleted entry.  This DEBUG_LIST specific warning is easier to
understand than the generic Oops message caused by LIST_POISON
dereference.

Signed-off-by: Baruch Siach <baruch@tkos.co.il>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2010-08-09 20:45:08 -07:00
Dave Jones
924d9addb9 list debugging: use WARN() instead of BUG()
Arjan noted that the list_head debugging is BUG'ing when it detects
corruption.  By causing the box to panic immediately, we're possibly
losing some bug reports.  Changing this to a WARN() should mean we at the
least start seeing reports collected at kerneloops.org

Signed-off-by: Dave Jones <davej@redhat.com>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 10:53:29 -07:00
Robert P. J. Day
e0ce0da9fe lists: remove a redundant conditional definition of list_add()
Remove the conditional surrounding the definition of list_add() from list.h
since, if you define CONFIG_DEBUG_LIST, the definition you will subsequently
pick up from lib/list_debug.c will be absolutely identical, at which point you
can remove that redundant definition from list_debug.c as well.

Signed-off-by: Robert P. J. Day <rpjday@crashcourse.ca>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 10:53:27 -07:00
Dave Jones
8f63fdbbd6 [PATCH] More list debugging context
Print the other (hopefully) known good pointer when list_head debugging
too, which may yield additional clues.

Also fix for 80-columns to win akpm brownie points.

Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-12-07 08:39:35 -08:00
Andrew Morton
ab8e92efcf [PATCH] list_del-debug fix
These two BUG_ON()s are redundant and undesired: we're checking for this
condition further on in the function, only better.

Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-01 00:39:17 -07:00
Manfred Spraul
df89a86463 [PATCH] list_del debug check
A list_del() debugging check.  Has been in -mm for years.  Dave moved
list_del() out-of-line in the debug case, so this is now suitable for
mainline.

Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:05 -07:00
Dave Jones
199a9afc3d [PATCH] Debug variants of linked list macros
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:05 -07:00