From: Yuto Ohnuki <ytohnuki@amazon.com> stable inclusion from stable-v6.6.130 commit 75669e987137f49c99ca44406bf0200d1892dd16 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14195 CVE: CVE-2026-31453 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=t... -------------------------------- commit 394d70b86fae9fe865e7e6d9540b7696f73aa9b6 upstream. In xfs_inode_item_push() and xfs_qm_dquot_logitem_push(), the AIL lock is dropped to perform buffer IO. Once the cluster buffer no longer protects the log item from reclaim, the log item may be freed by background reclaim or the dquot shrinker. The subsequent spin_lock() call dereferences lip->li_ailp, which is a use-after-free. Fix this by saving the ailp pointer in a local variable while the AIL lock is held and the log item is guaranteed to be valid. Reported-by: syzbot+652af2b3c5569c4ab63c@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=652af2b3c5569c4ab63c Fixes: 90c60e164012 ("xfs: xfs_iflush() is no longer necessary") Cc: stable@vger.kernel.org # v5.9 Reviewed-by: Darrick J. Wong <djwong@kernel.org> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Yuto Ohnuki <ytohnuki@amazon.com> Signed-off-by: Carlos Maiolino <cem@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: fs/xfs/xfs_inode_item.c [Context conflicts] Signed-off-by: Long Li <leo.lilong@huawei.com> --- fs/xfs/xfs_dquot_item.c | 9 +++++++-- fs/xfs/xfs_inode_item.c | 9 +++++++-- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/fs/xfs/xfs_dquot_item.c b/fs/xfs/xfs_dquot_item.c index 7d19091215b0..74449aec81ed 100644 --- a/fs/xfs/xfs_dquot_item.c +++ b/fs/xfs/xfs_dquot_item.c @@ -125,6 +125,7 @@ xfs_qm_dquot_logitem_push( { struct xfs_dquot *dqp = DQUOT_ITEM(lip)->qli_dquot; struct xfs_buf *bp = lip->li_buf; + struct xfs_ail *ailp = lip->li_ailp; uint rval = XFS_ITEM_SUCCESS; int error; @@ -153,7 +154,7 @@ xfs_qm_dquot_logitem_push( goto out_unlock; } - spin_unlock(&lip->li_ailp->ail_lock); + spin_unlock(&ailp->ail_lock); error = xfs_qm_dqflush(dqp, &bp); if (!error) { @@ -163,7 +164,11 @@ xfs_qm_dquot_logitem_push( } else if (error == -EAGAIN) rval = XFS_ITEM_LOCKED; - spin_lock(&lip->li_ailp->ail_lock); + /* + * The buffer no longer protects the log item from reclaim, so + * do not reference lip after this point. + */ + spin_lock(&ailp->ail_lock); out_unlock: xfs_dqunlock(dqp); return rval; diff --git a/fs/xfs/xfs_inode_item.c b/fs/xfs/xfs_inode_item.c index 950de5200656..33fc894febe2 100644 --- a/fs/xfs/xfs_inode_item.c +++ b/fs/xfs/xfs_inode_item.c @@ -727,6 +727,7 @@ xfs_inode_item_push( struct xfs_inode_log_item *iip = INODE_ITEM(lip); struct xfs_inode *ip = iip->ili_inode; struct xfs_buf *bp = lip->li_buf; + struct xfs_ail *ailp = lip->li_ailp; uint rval = XFS_ITEM_SUCCESS; int error; @@ -750,7 +751,7 @@ xfs_inode_item_push( if (!xfs_buf_trylock(bp)) return XFS_ITEM_LOCKED; - spin_unlock(&lip->li_ailp->ail_lock); + spin_unlock(&ailp->ail_lock); /* * We need to hold a reference for flushing the cluster buffer as it may @@ -774,7 +775,11 @@ xfs_inode_item_push( rval = XFS_ITEM_LOCKED; } - spin_lock(&lip->li_ailp->ail_lock); + /* + * The buffer no longer protects the log item from reclaim, so + * do not reference lip after this point. + */ + spin_lock(&ailp->ail_lock); return rval; } -- 2.52.0