linux-stable.git/kernel/debug, branch v5.7.7

kgdb: Prevent infinite recursive entries to the debugger

2020-06-22T07:32:23+00:00

[ Upstream commit 3ca676e4ca60d1834bb77535dafe24169cadacef ]

If we detect that we recursively entered the debugger we should hack
our I/O ops to NULL so that the panic() in the next line won't
actually cause another recursion into the debugger.  The first line of
kgdb_panic() will check this and return.

Signed-off-by: Douglas Anderson 
Reviewed-by: Daniel Thompson 
Link: https://lore.kernel.org/r/20200507130644.v4.6.I89de39f68736c9de610e6f241e68d8dbc44bc266@changeid
Signed-off-by: Daniel Thompson 
Signed-off-by: Sasha Levin

kgdb: Disable WARN_CONSOLE_UNLOCKED for all kgdb

2020-06-22T07:32:23+00:00

[ Upstream commit 202164fbfa2b2ffa3e66b504e0f126ba9a745006 ]

In commit 81eaadcae81b ("kgdboc: disable the console lock when in
kgdb") we avoided the WARN_CONSOLE_UNLOCKED() yell when we were in
kgdboc.  That still works fine, but it turns out that we get a similar
yell when using other I/O drivers.  One example is the "I/O driver"
for the kgdb test suite (kgdbts).  When I enabled that I again got the
same yells.

Even though "kgdbts" doesn't actually interact with the user over the
console, using it still causes kgdb to print to the consoles.  That
trips the same warning:
  con_is_visible+0x60/0x68
  con_scroll+0x110/0x1b8
  lf+0x4c/0xc8
  vt_console_print+0x1b8/0x348
  vkdb_printf+0x320/0x89c
  kdb_printf+0x68/0x90
  kdb_main_loop+0x190/0x860
  kdb_stub+0x2cc/0x3ec
  kgdb_cpu_enter+0x268/0x744
  kgdb_handle_exception+0x1a4/0x200
  kgdb_compiled_brk_fn+0x34/0x44
  brk_handler+0x7c/0xb8
  do_debug_exception+0x1b4/0x228

Let's increment/decrement the "ignore_console_lock_warning" variable
all the time when we enter the debugger.

This will allow us to later revert commit 81eaadcae81b ("kgdboc:
disable the console lock when in kgdb").

Signed-off-by: Douglas Anderson 
Reviewed-by: Greg Kroah-Hartman 
Reviewed-by: Daniel Thompson 
Link: https://lore.kernel.org/r/20200507130644.v4.1.Ied2b058357152ebcc8bf68edd6f20a11d98d7d4e@changeid
Signed-off-by: Daniel Thompson 
Signed-off-by: Sasha Levin

Merge tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx

2020-04-03T20:12:26+00:00

Pull SPDX updates from Greg KH:
 "Here are three SPDX patches for 5.7-rc1.

  One fixes up the SPDX tag for a single driver, while the other two go
  through the tree and add SPDX tags for all of the .gitignore files as
  needed.

  Nothing too complex, but you will get a merge conflict with your
  current tree, that should be trivial to handle (one file modified by
  two things, one file deleted.)

  All three of these have been in linux-next for a while, with no
  reported issues other than the merge conflict"

* tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
  ASoC: MT6660: make spdxcheck.py happy
  .gitignore: add SPDX License Identifier
  .gitignore: remove too obvious comments

kdb: Censor attempts to set PROMPT without ENABLE_MEM_READ

2020-04-01T15:59:11+00:00

Currently the PROMPT variable could be abused to provoke the printf()
machinery to read outside the current stack frame. Normally this
doesn't matter becaues md is already a much better tool for reading
from memory.

However the md command can be disabled by not setting KDB_ENABLE_MEM_READ.
Let's also prevent PROMPT from being modified in these circumstances.

Whilst adding a comment to help future code reviewers we also remove
the #ifdef where PROMPT in consumed. There is no problem passing an
unused (0) to snprintf when !CONFIG_SMP.
argument

Reported-by: Wang Xiayang 
Signed-off-by: Daniel Thompson 
Reviewed-by: Douglas Anderson

kdb: Eliminate strncpy() warnings by replacing with strscpy()

2020-04-01T15:59:02+00:00

Currently the code to manage the kdb history buffer uses strncpy() to
copy strings to/and from the history and exhibits the classic "but
nobody ever told me that strncpy() doesn't always terminate strings"
bug. Modern gcc compilers recognise this bug and issue a warning.

In reality these calls will only abridge the copied string if kdb_read()
has *already* overflowed the command buffer. Thus the use of counted
copies here is only used to reduce the secondary effects of a bug
elsewhere in the code.

Therefore transitioning these calls into strscpy() (without checking
the return code) is appropriate.

Signed-off-by: Daniel Thompson 
Reviewed-by: Douglas Anderson

.gitignore: add SPDX License Identifier

2020-03-25T10:50:48+00:00

Add SPDX License Identifier to all .gitignore files.

Signed-off-by: Masahiro Yamada 
Signed-off-by: Greg Kroah-Hartman

Revert "kdb: Get rid of confusing diag msg from "rd" if current task has no regs"

2020-02-06T11:40:09+00:00

This reverts commit bbfceba15f8d1260c328a254efc2b3f2deae4904.

When DBG_MAX_REG_NUM is zero then a number of symbols are conditionally
defined. It is therefore not possible to check it using C expressions.

Reported-by: Anatoly Pugachev 
Acked-by: Doug Anderson 
Signed-off-by: Daniel Thompson

kdb: Use for_each_console() helper

2020-01-31T17:34:54+00:00

Replace open coded single-linked list iteration loop with for_each_console()
helper in use.

Signed-off-by: Andy Shevchenko 
Signed-off-by: Daniel Thompson

kdb: remove redundant assignment to pointer bp

2020-01-31T17:34:06+00:00

The point bp is assigned a value that is never read, it is being
re-assigned later to bp = &kdb_breakpoints[lowbp] in a for-loop.
Remove the redundant assignment.

Addresses-Coverity ("Unused value")
Signed-off-by: Colin Ian King 
Link: https://lore.kernel.org/r/20191128130753.181246-1-colin.king@canonical.com
Signed-off-by: Daniel Thompson

kdb: Get rid of confusing diag msg from "rd" if current task has no regs

2020-01-31T17:34:03+00:00

If you switch to a sleeping task with the "pid" command and then type
"rd", kdb tells you this:

  No current kdb registers.  You may need to select another task
  diag: -17: Invalid register name

The first message makes sense, but not the second.  Fix it by just
returning 0 after commands accessing the current registers finish if
we've already printed the "No current kdb registers" error.

While fixing kdb_rd(), change the function to use "if" rather than
"ifdef".  It cleans the function up a bit and any modern compiler will
have no trouble handling still producing good code.

Signed-off-by: Douglas Anderson 
Link: https://lore.kernel.org/r/20191109111624.5.I121f4c6f0c19266200bf6ef003de78841e5bfc3d@changeid
Signed-off-by: Daniel Thompson