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([2a02:4e0:2d18:46e:3ea5:404b:a2c:3af8]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47a8f74b17bsm12292445e9.2.2025.12.11.21.10.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Dec 2025 21:10:27 -0800 (PST) From: Ahmet Eray Karadag To: clm@fb.com, dsterba@suse.com Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org, david.hunter.linux@gmail.com, skhan@linuxfoundation.org, Ahmet Eray Karadag , syzbot+2f8aa76e6acc9fce6638@syzkaller.appspotmail.com Subject: [PATCH] btrfs: fix qgroup extent_changeset leak in page_mkwrite Date: Fri, 12 Dec 2025 08:09:48 +0300 Message-ID: <20251212050947.148242-2-eraykrdg1@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" syzbot reported a memory leak originating from ulist_prealloc() called from qgroup_reserve_data() in the btrfs_page_mkwrite() path. When btrfs_check_data_free_space() succeeds and btrfs_delalloc_reserve_metadata() later fails, we free the data reservation via btrfs_free_reserved_data_space(), but we never free the extent_changeset pointed to by data_reserved. Add the missing extent_changeset_free(data_reserved) in this error path, matching the other exit paths in btrfs_page_mkwrite() and the failure handling in btrfs_check_data_free_space(). Reported-by: syzbot+2f8aa76e6acc9fce6638@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3D2f8aa76e6acc9fce6638 Signed-off-by: Ahmet Eray Karadag --- fs/btrfs/file.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c index 7a501e73d880..4b05e72249e2 100644 --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1910,6 +1910,8 @@ static vm_fault_t btrfs_page_mkwrite(struct vm_fault = *vmf) if (!only_release_metadata) btrfs_free_reserved_data_space(inode, data_reserved, page_start, reserved_space); + extent_changeset_free(data_reserved); + data_reserved =3D NULL; goto out_noreserve; } =20 --=20 2.43.0