3.16.62-rc1 review patch. If anyone has any objections, please let me know.
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From: Tomi Valkeinen tomi.valkeinen@ti.com
commit 1bafcbf59fed92af58955024452f45430d3898c5 upstream.
OMAPFB_MEMORY_READ ioctl reads pixels from the LCD's memory and copies them to a userspace buffer. The code has two issues:
- The user provided width and height could be large enough to overflow the calculations - The copy_to_user() can copy uninitialized memory to the userspace, which might contain sensitive kernel information.
Fix these by limiting the width & height parameters, and only copying the amount of data that we actually received from the LCD.
Signed-off-by: Tomi Valkeinen tomi.valkeinen@ti.com Reported-by: Jann Horn jannh@google.com Cc: security@kernel.org Cc: Will Deacon will.deacon@arm.com Cc: Jann Horn jannh@google.com Cc: Tony Lindgren tony@atomide.com Signed-off-by: Bartlomiej Zolnierkiewicz b.zolnierkie@samsung.com Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
--- a/drivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c +++ b/drivers/video/fbdev/omap2/omapfb/omapfb-ioctl.c @@ -493,6 +493,9 @@ static int omapfb_memory_read(struct fb_ if (!access_ok(VERIFY_WRITE, mr->buffer, mr->buffer_size)) return -EFAULT;
+ if (mr->w > 4096 || mr->h > 4096) + return -EINVAL; + if (mr->w * mr->h * 3 > mr->buffer_size) return -EINVAL;
@@ -506,7 +509,7 @@ static int omapfb_memory_read(struct fb_ mr->x, mr->y, mr->w, mr->h);
if (r > 0) { - if (copy_to_user(mr->buffer, buf, mr->buffer_size)) + if (copy_to_user(mr->buffer, buf, r)) r = -EFAULT; }