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Commit c32b8f70 authored by Jin Qian's avatar Jin Qian Committed by TARKZiM
Browse files

uid_sys_stats: fix overflow when io usage delta is negative 



Setuid can cause negative delta. Check this and update total usage only
if delta is positive.

Bug: 64317562
Change-Id: I4818c246db66cabf3b11d277faceedec1678694a
Signed-off-by: default avatarJin Qian <jinqian@google.com>
parent e7366b94

drivers/misc/uid_cputime.c

+21 −5
Original line number Diff line number Diff line
@@ -235,13 +235,29 @@ static void compute_uid_io_bucket_stats(struct io_stats *io_bucket, 
					struct io_stats *io_last,

					struct io_stats *io_dead)

{

	io_bucket->read_bytes += io_curr->read_bytes + io_dead->read_bytes -

	s64 delta;



	delta = io_curr->read_bytes + io_dead->read_bytes -

		io_last->read_bytes;

	io_bucket->write_bytes += io_curr->write_bytes + io_dead->write_bytes -

	if (delta > 0)

		io_bucket->read_bytes += delta;



	delta = io_curr->write_bytes + io_dead->write_bytes -

		io_last->write_bytes;

	io_bucket->rchar += io_curr->rchar + io_dead->rchar - io_last->rchar;

	io_bucket->wchar += io_curr->wchar + io_dead->wchar - io_last->wchar;

	io_bucket->fsync += io_curr->fsync + io_dead->fsync - io_last->fsync;

	if (delta > 0)

		io_bucket->write_bytes += delta;



	delta = io_curr->rchar + io_dead->rchar - io_last->rchar;

	if (delta > 0)

		io_bucket->rchar += delta;



	delta = io_curr->wchar + io_dead->wchar - io_last->wchar;

	if (delta > 0)

		io_bucket->wchar += delta;



	delta = io_curr->fsync + io_dead->fsync - io_last->fsync;

	if (delta > 0)

		io_bucket->fsync += delta;



	io_last->read_bytes = io_curr->read_bytes;

	io_last->write_bytes = io_curr->write_bytes;