linux-stable.git/kernel/debug/kdb/kdb_io.c, branch v3.18.136

kdb: Use strscpy with destination buffer size

2018-12-01T08:47:59+00:00

[ Upstream commit c2b94c72d93d0929f48157eef128c4f9d2e603ce ]

gcc 8.1.0 warns with:

kernel/debug/kdb/kdb_support.c: In function ‘kallsyms_symbol_next’:
kernel/debug/kdb/kdb_support.c:239:4: warning: ‘strncpy’ specified bound depends on the length of the source argument [-Wstringop-overflow=]
     strncpy(prefix_name, name, strlen(name)+1);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
kernel/debug/kdb/kdb_support.c:239:31: note: length computed here

Use strscpy() with the destination buffer size, and use ellipses when
displaying truncated symbols.

v2: Use strscpy()

Signed-off-by: Prarit Bhargava 
Cc: Jonathan Toppins 
Cc: Jason Wessel 
Cc: Daniel Thompson 
Cc: kgdb-bugreport@lists.sourceforge.net
Reviewed-by: Daniel Thompson 
Signed-off-by: Daniel Thompson 
Signed-off-by: Sasha Levin

kdb: Fix handling of kallsyms_symbol_next() return value

2017-12-16T09:32:27+00:00

commit c07d35338081d107e57cf37572d8cc931a8e32e2 upstream.

kallsyms_symbol_next() returns a boolean (true on success). Currently
kdb_read() tests the return value with an inequality that
unconditionally evaluates to true.

This is fixed in the obvious way and, since the conditional branch is
supposed to be unreachable, we also add a WARN_ON().

Reported-by: Dan Carpenter 
Signed-off-by: Daniel Thompson 
Signed-off-by: Jason Wessel 
Signed-off-by: Greg Kroah-Hartman

kernel/printk: use symbolic defines for console loglevels

2014-06-04T23:54:17+00:00

... instead of naked numbers.

Stuff in sysrq.c used to set it to 8 which is supposed to mean above
default level so set it to DEBUG instead as we're terminating/killing all
tasks and we want to be verbose there.

Also, correct the check in x86_64_start_kernel which should be >= as
we're clearly issuing the string there for all debug levels, not only
the magical 10.

Signed-off-by: Borislav Petkov 
Acked-by: Kees Cook 
Acked-by: Randy Dunlap 
Cc: Joe Perches 
Cc: Valdis Kletnieks 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kdb,vt_console: Fix missed data due to pager overruns

2012-10-12T11:37:35+00:00

It is possible to miss data when using the kdb pager.  The kdb pager
does not pay attention to the maximum column constraint of the screen
or serial terminal.  This result is not incrementing the shown lines
correctly and the pager will print more lines that fit on the screen.
Obviously that is less than useful when using a VGA console where you
cannot scroll back.

The pager will now look at the kdb_buffer string to see how many
characters are printed.  It might not be perfect considering you can
output ASCII that might move the cursor position, but it is a
substantially better approximation for viewing dmesg and trace logs.

This also means that the vt screen needs to set the kdb COLUMNS
variable.

Cc: 
Signed-off-by: Jason Wessel

kdb: Remove cpu from the more prompt

2012-07-31T13:16:43+00:00

Having the CPU in the more prompt is completely redundent vs the
standard kdb prompt, and it also wastes 32 bytes on the stack.

Signed-off-by: Jason Wessel

kdb: Fix smatch warning on dbg_io_ops->is_console

2012-03-29T22:41:23+00:00

The Smatch tool warned that the change from commit b8adde8dd
(kdb: Avoid using dbg_io_ops until it is initialized) should
add another null check later in the kdb_printf().

It is worth noting that the second use of dbg_io_ops->is_console
is protected by the KDB_PAGER state variable which would only
get set when kdb is fully active and initialized.  If we
ever encounter changes or defects in the KDB_PAGER state
we do not want to crash the kernel in a kdb_printf/printk.

CC: Tim Bird 
Reported-by: Dan Carpenter 
Signed-off-by: Jason Wessel

kdb: Avoid using dbg_io_ops until it is initialized

2012-03-22T20:07:16+00:00

This fixes a bug with setting a breakpoint during kdb initialization
(from kdb_cmds).  Any call to kdb_printf() before the initialization
of the kgdboc serial console driver (which happens much later during
bootup than kdb_init), results in kernel panic due to the use of
dbg_io_ops before it is initialized.

Signed-off-by: Tim Bird 
Signed-off-by: Jason Wessel

kdb,kgdb: Allow arbitrary kgdb magic knock sequences

2011-08-01T18:23:59+00:00

The first packet that gdb sends when the kernel is in kdb mode seems
to change with every release of gdb.  Instead of continuing to add
many different gdb packets, change kdb to automatically look for any
thing that looks like a gdb packet.

Example 1 cold start test:
echo g > /proc/sysrq-trigger
$D#44+

Example 2 cold start test:
echo g > /proc/sysrq-trigger
$3#33

The second one should re-enter kdb's shell right away and is purely a
test.

Signed-off-by: Jason Wessel

kdb: Remove all references to DOING_KGDB2

2011-08-01T18:23:59+00:00

The DOING_KGDB2 was originally a state variable for one of the two
ways to automatically transition from kdb to kgdb.  Purge all these
variables and just use one single state for the transition.

Signed-off-by: Jason Wessel

kdb,kgdb: Implement switch and pass buffer from kdb -> gdb

2011-08-01T18:23:59+00:00

When switching from kdb mode to kgdb mode packets were getting lost
depending on the size of the fifo queue of the serial chip.  When gdb
initially connects if it is in kdb mode it should entirely send any
character buffer over to the gdbstub when switching connections.

Previously kdb was zero'ing out the character buffer and this could
lead to gdb failing to connect at all, or a lengthy pause could occur
on the initial connect.

Signed-off-by: Jason Wessel