6.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Christoph Hellwig <hch@xxxxxx>
commit 07eae0fa67ca4bbb199ad85645e0f9dfaef931cd upstream.
Commit 32dd4f9c506b ("xfs: remove a superflous hash lookup when inserting
new buffers") converted xfs_buf_find_insert to use
rhashtable_lookup_get_insert_fast and thus an operation that returns the
existing buffer when an insert would duplicate the hash key. But this
code path misses the check for a buffer with a reference count of zero,
which could lead to reusing an about to be freed buffer. Fix this by
using the same atomic_inc_not_zero pattern as xfs_buf_insert.
Fixes: 32dd4f9c506b ("xfs: remove a superflous hash lookup when inserting new buffers")
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Darrick J. Wong <djwong@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # v6.0
Signed-off-by: Carlos Maiolino <cem@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/xfs/xfs_buf.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/fs/xfs/xfs_buf.c
+++ b/fs/xfs/xfs_buf.c
@@ -663,9 +663,8 @@ xfs_buf_find_insert(
spin_unlock(&bch->bc_lock);
goto out_free_buf;
}
- if (bp) {
+ if (bp && atomic_inc_not_zero(&bp->b_hold)) {
/* found an existing buffer */
- atomic_inc(&bp->b_hold);
spin_unlock(&bch->bc_lock);
error = xfs_buf_find_lock(bp, flags);
if (error)
