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drivers/gpu/vga: allocate vga_arb_write() buffer on stack 

Size of kmalloc() in vga_arb_write() is controlled by user.
Too large kmalloc() size triggers WARNING message on console.
Allocate the buffer on stack to avoid the WARNING.
The string must be small (e.g "target PCI:domain:bus:dev.fn").

Signed-off-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: dri-devel@lists.freedesktop.org
Cc: syzkaller@googlegroups.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/1476451342-146510-1-git-send-email-dvyukov@google.com
This commit is contained in:
Dmitry Vyukov 2016-10-14 15:22:22 +02:00 committed by Daniel Vetter
parent 0853695c3b
commit 49521b13cb
1 changed files with 4 additions and 11 deletions
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15
drivers/gpu/vga/vgaarb.c
View File

@ -1022,21 +1022,16 @@ static ssize_t vga_arb_write(struct file *file, const char __user *buf,
unsigned int io_state;
char *kbuf, *curr_pos;
char kbuf[64], *curr_pos;
size_t remaining = count;
int ret_val;
int i;
kbuf = kmalloc(count + 1, GFP_KERNEL);
if (!kbuf)
return -ENOMEM;
if (copy_from_user(kbuf, buf, count)) {
kfree(kbuf);
if (count >= sizeof(kbuf))
return -EINVAL;
if (copy_from_user(kbuf, buf, count))
return -EFAULT;
}
curr_pos = kbuf;
kbuf[count] = '\0'; /* Just to make sure... */
@ -1259,11 +1254,9 @@ static ssize_t vga_arb_write(struct file *file, const char __user *buf,
goto done;
}
/* If we got here, the message written is not part of the protocol! */
kfree(kbuf);
return -EPROTO;
done:
kfree(kbuf);
return ret_val;
}