tree 524d326c77b78a3f6945248001224c7cad181197
parent a23f89a2f05a42a23fd974f537a2213d00e72b66
author Benjamin Gordon <bmgordon@chromium.org> 1608084867 -0700
committer Commit Bot <commit-bot@chromium.org> 1608173197 +0000

lorgnette: Enforce maximum scan buffer size

When starting to return a page, a scanner can claim arbitrary
dimensions.  Lorgnette reads line by line through a modest-sized buffer,
but this could still result in creating an output PNG of unbounded size.
To avoid this, ensure that the scanner's claimed parameters are
self-consistent values that don't result in more than 400MB of raw data.
This limit is enough to scan:

  * An 11x17 ledger page at 600 dpi in 16-bit color.
  * An 8.5x40 banner from the ADF at 600 dpi in 16-bit color.
  * An 8.5x11 letter page at 1200 dpi in 8-bit color.

Since the frontend currently limits requests to 600 dpi and 8-bit
color, this limit should provide a safety net without hampering any
realistic consumer-level scanner.

BUG=b:175588023
TEST=New unit test

Change-Id: Ie0944a1865e176beec38415be033e510d4e9e526
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform2/+/2594491
Commit-Queue: Benjamin Gordon <bmgordon@chromium.org>
Tested-by: Benjamin Gordon <bmgordon@chromium.org>
Reviewed-by: Allen Webb <allenwebb@google.com>
Reviewed-by: Jesse Schettler <jschettler@chromium.org>