In the Linux kernel, the following vulnerability has been resolved:

gfs2: ignore negated quota changes

When lots of quota changes are made, there may be cases in which an
inode's quota information is increased and then decreased, such as when
blocks are added to a file, then deleted from it. If the timing is
right, function do_qc can add pending quota changes to a transaction,
then later, another call to do_qc can negate those changes, resulting
in a net gain of 0. The quota_change information is recorded in the qc
buffer (and qd element of the inode as well). The buffer is added to the
transaction by the first call to do_qc, but a subsequent call changes
the value from non-zero back to zero. At that point it's too late to
remove the buffer_head from the transaction. Later, when the quota sync
code is called, the zero-change qd element is discovered and flagged as
an assert warning. If the fs is mounted with errors=panic, the kernel
will panic.

This is usually seen when files are truncated and the quota changes are
negated by punch_hole/truncate which uses gfs2_quota_hold and
gfs2_quota_unhold rather than block allocations that use gfs2_quota_lock
and gfs2_quota_unlock which automatically do quota sync.

This patch solves the problem by adding a check to qd_check_sync such
that net-zero quota changes already added to the transaction are no
longer deemed necessary to be synced, and skipped.

In this case references are taken for the qd and the slot from do_qc
so those need to be put. The normal sequence of events for a normal
non-zero quota change is as follows:

gfs2_quota_change
   do_qc
      qd_hold
      slot_hold

Later, when the changes are to be synced:

gfs2_quota_sync
   qd_fish
      qd_check_sync
         gets qd ref via lockref_get_not_dead
   do_sync
      do_qc(QC_SYNC)
         qd_put
	    lockref_put_or_lock
   qd_unlock
      qd_put
         lockref_put_or_lock

In the net-zero change case, we add a check to qd_check_sync so it puts
the qd and slot references acquired in gfs2_quota_change and skip the
unneeded sync.

Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.

CVE: https://git.kernel.org/stable/c/119565e566f91ff3588ffcd5812f0c8061586c6b

CVE: https://git.kernel.org/stable/c/1c28dace66015b675a343b89b0c87abbfda05ff4

CVE: https://git.kernel.org/stable/c/212f112fe5e90e98eb8d48585682880dae139f4c

CVE: https://git.kernel.org/stable/c/2a054b87a1b799b391e578597a42ee6e57a987ae

CVE: https://git.kernel.org/stable/c/2bb42a27a92ff3984c9fa5fbe128eced3ea693f2

CVE: https://git.kernel.org/stable/c/4c6a08125f2249531ec01783a5f4317d7342add5

CVE: https://git.kernel.org/stable/c/53fc16c1ad84f5467ec24341670b63aa759335d3

CVE: https://git.kernel.org/stable/c/5bfda356e903633d16ae1bac1ee38364e12628a3

CVE: https://git.kernel.org/stable/c/b4deec69fe32b58dc5fb4ace52456ece85b75561

kernel.org: https://git.kernel.org/stable/c/119565e566f91ff3588ffcd5812f0c8061586c6b

kernel.org: https://git.kernel.org/stable/c/1c28dace66015b675a343b89b0c87abbfda05ff4

kernel.org: https://git.kernel.org/stable/c/212f112fe5e90e98eb8d48585682880dae139f4c

kernel.org: https://git.kernel.org/stable/c/2a054b87a1b799b391e578597a42ee6e57a987ae

kernel.org: https://git.kernel.org/stable/c/2bb42a27a92ff3984c9fa5fbe128eced3ea693f2

kernel.org: https://git.kernel.org/stable/c/4c6a08125f2249531ec01783a5f4317d7342add5

kernel.org: https://git.kernel.org/stable/c/50e33567bc4a1c4ed79a1d289fe93c9a26491848

kernel.org: https://git.kernel.org/stable/c/53fc16c1ad84f5467ec24341670b63aa759335d3

kernel.org: https://git.kernel.org/stable/c/5bfda356e903633d16ae1bac1ee38364e12628a3

kernel.org: https://git.kernel.org/stable/c/b4deec69fe32b58dc5fb4ace52456ece85b75561