Messages in this thread | | | Date | Mon, 2 Feb 2009 15:54:48 -0800 | From | Andrew Morton <> | Subject | Re: [PATCH] Fix memory corruption in console selection |
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On Fri, 30 Jan 2009 15:27:14 -0500 (EST) Mikulas Patocka <mpatocka@redhat.com> wrote:
> [ I don't know who is the console maintainer or if there is any, so I'm > posting this to Linus ] > > > Fix an off-by-two memory error in console selection. > > The loop below goes from sel_start to sel_end (inclusive), so it writes > one more character. This one more character was added to the allocated > size (+1), but it was not multiplied by an UTF-8 multiplier. > > This patch fixes a memory corruption when UTF-8 console is used and the > user selects a few characters, all of them 3-byte in UTF-8 (for example a > frame line). > > When memory redzones are enabled, a redzone corruption is reported. When > they are not enabled, trashing of random memory occurs. > > Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> > > --- > drivers/char/selection.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6.29-rc3-devel/drivers/char/selection.c > =================================================================== > --- linux-2.6.29-rc3-devel.orig/drivers/char/selection.c 2009-01-30 21:03:07.000000000 +0100 > +++ linux-2.6.29-rc3-devel/drivers/char/selection.c 2009-01-30 21:03:38.000000000 +0100 > @@ -268,7 +268,7 @@ int set_selection(const struct tiocl_sel > > /* Allocate a new buffer before freeing the old one ... */ > multiplier = use_unicode ? 3 : 1; /* chars can take up to 3 bytes */ > - bp = kmalloc((sel_end-sel_start)/2*multiplier+1, GFP_KERNEL); > + bp = kmalloc(((sel_end-sel_start)/2+1)*multiplier, GFP_KERNEL); > if (!bp) { > printk(KERN_WARNING "selection: kmalloc() failed\n"); > clear_selection();
The patch is now in mainline for 2.6.29, as 878b8619f711280fd05845e21956434b5e588cc4.
It appears to be applicable to earlier kernels as far back as 2.6.25 (at least). But the -stable maintainers were not informed of this.
An appropriate way of flagging this is to add
Cc: <stable@kernel.org>
to the changelog.
Please, people - we all need to think about this, to prevent stuff from falling through cracks.
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