linux-toradex.git/kernel/printk.c, branch v3.2.73

console: Fix console name size mismatch

2015-05-09T22:16:24+00:00

commit 30a22c215a0007603ffc08021f2e8b64018517dd upstream.

commit 6ae9200f2cab7 ("enlarge console.name") increased the storage
for the console name to 16 bytes, but not the corresponding
struct console_cmdline::name storage. Console names longer than
8 bytes cause read beyond end-of-string and failure to match
console; I'm not sure if there are other unexpected consequences.

Signed-off-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman 
[bwh: Backported to 3.2:
 - Adjust filename
 - Use console_cmdline[i] instead of *c]
Signed-off-by: Ben Hutchings

printk: Fix scheduling-while-atomic problem in console_cpu_notify()

2014-04-01T23:59:00+00:00

commit 85eae82a0855d49852b87deac8653e4ebc8b291f upstream.

The console_cpu_notify() function runs with interrupts disabled in the
CPU_DYING case.  It therefore cannot block, for example, as will happen
when it calls console_lock().  Therefore, remove the CPU_DYING leg of
the switch statement to avoid this problem.

Signed-off-by: Paul E. McKenney 
Reviewed-by: Srivatsa S. Bhat 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

printk: Fix rq->lock vs logbuf_lock unlock lock inversion

2013-07-27T04:34:04+00:00

commit dbda92d16f8655044e082930e4e9d244b87fde77 upstream.

commit 07354eb1a74d1 ("locking printk: Annotate logbuf_lock as raw")
reintroduced a lock inversion problem which was fixed in commit
0b5e1c5255 ("printk: Release console_sem after logbuf_lock"). This
happened probably when fixing up patch rejects.

Restore the ordering and unlock logbuf_lock before releasing
console_sem.

Signed-off-by: ybu 
Cc: Peter Zijlstra 
Link: http://lkml.kernel.org/r/E807E903FE6CBE4D95E420FBFCC273B827413C@nasanexd01h.na.qualcomm.com
Signed-off-by: Thomas Gleixner 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

printk: fix buffer overflow when calling log_prefix function from call_console_drivers

2013-02-06T04:33:57+00:00

This patch corrects a buffer overflow in kernels from 3.0 to 3.4 when calling
log_prefix() function from call_console_drivers().

This bug existed in previous releases but has been revealed with commit
162a7e7500f9664636e649ba59defe541b7c2c60 (2.6.39 => 3.0) that made changes
about how to allocate memory for early printk buffer (use of memblock_alloc).
It disappears with commit 7ff9554bb578ba02166071d2d487b7fc7d860d62 (3.4 => 3.5)
that does a refactoring of printk buffer management.

In log_prefix(), the access to "p[0]", "p[1]", "p[2]" or
"simple_strtoul(&p[1], &endp, 10)" may cause a buffer overflow as this
function is called from call_console_drivers by passing "&LOG_BUF(cur_index)"
where the index must be masked to do not exceed the buffer's boundary.

The trick is to prepare in call_console_drivers() a buffer with the necessary
data (PRI field of syslog message) to be safely evaluated in log_prefix().

This patch can be applied to stable kernel branches 3.0.y, 3.2.y and 3.4.y.

Without this patch, one can freeze a server running this loop from shell :
  $ export DUMMY=`cat /dev/urandom | tr -dc '12345AZERTYUIOPQSDFGHJKLMWXCVBNazertyuiopqsdfghjklmwxcvbn' | head -c255`
  $ while true do ; echo $DUMMY > /dev/kmsg ; done

The "server freeze" depends on where memblock_alloc does allocate printk buffer :
if the buffer overflow is inside another kernel allocation the problem may not
be revealed, else the server may hangs up.

Signed-off-by: Alexandre SIMON 
Signed-off-by: Ben Hutchings

printk: avoid double lock acquire

2011-12-09T15:50:28+00:00

Commit 4f2a8d3cf5e ("printk: Fix console_sem vs logbuf_lock unlock race")
introduced another silly bug where we would want to acquire an already
held lock.  Avoid this.

Reported-by: Andrea Arcangeli 
Signed-off-by: Peter Zijlstra 
Cc: Ingo Molnar 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

printk: remove bounds checking for log_prefix

2011-11-01T00:30:53+00:00

Currently log_prefix is testing that the first character of the log level
and facility is less than '0' and greater than '9' (which is always
false).

Since the code being updated works because strtoul bombs out (endp isn't
updated) and 0 is returned anyway just remove the check and don't change
the behavior of the function.

Signed-off-by: William Douglas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

printk: fix bounds checking for log_prefix

2011-11-01T00:30:53+00:00

Currently log_prefix is testing that the first character of the log level
and facility is less than '0' and greater than '9' (which is always
false).  It should be testing to see if the character less than '0' or
greater than '9' instead.  This patch makes that change.

The code being changed worked because strtoul bombs out (endp isn't
updated) and 0 is returned anyway.

Signed-off-by: William Douglas 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

printk: add console_suspend module parameter

2011-11-01T00:30:53+00:00

We are enabling some power features on medfield.  To test suspend-2-RAM
conveniently, we need turn on/off console_suspend_enabled frequently.

Add a module parameter, so users could change it by:
/sys/module/printk/parameters/console_suspend

Signed-off-by: Yanmin Zhang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

printk: add module parameter ignore_loglevel to control ignore_loglevel

2011-11-01T00:30:53+00:00

We are enabling some power features on medfield.  To test suspend-2-RAM
conveniently, we need turn on/off ignore_loglevel frequently without
rebooting.

Add a module parameter, so users can change it by:
/sys/module/printk/parameters/ignore_loglevel

Signed-off-by: Yanmin Zhang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

locking, printk: Annotate logbuf_lock as raw

2011-09-13T09:11:54+00:00

The logbuf_lock lock can be taken in atomic context and therefore
cannot be preempted on -rt - annotate it.

In mainline this change documents the low level nature of
the lock - otherwise there's no functional difference. Lockdep
and Sparse checking will work as usual.

Signed-off-by: Thomas Gleixner 
[ merged and fixed it ]
Signed-off-by: Ingo Molnar