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[34.83.123.78]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-39e6c5b3932sm11742139a91.13.2026.09.20.21.25.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Sep 2026 21:25:14 -0700 (PDT) From: Hui Peng To: Damien Le Moal , Christian Brauner , Jan Kara , Jeff Layton Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Hui Peng Subject: [PATCH v2 4/6] qnx6: release sb_buf on mmi_fs error path in qnx6_fill_super() Date: Mon, 21 Sep 2026 04:25:09 +0000 Message-ID: <20260921042511.1473629-4-benquike@gmail.com> X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog In-Reply-To: <20260921042511.1473629-1-benquike@gmail.com> References: <20260919222556.3792829-1-benquike@gmail.com> <20260921042511.1473629-1-benquike@gmail.com> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit When mounting with "-o mmi_fs" (QNX6_MOUNT_MMI_FS), qnx6_mmi_fill_super() allocates the active superblock buffer_head and stores it in qs->sb_buf (QNX6_SB(s)->sb_buf), while qnx6_fill_super()'s local bh1 and bh2 pointers remain NULL, and jumps to mmi_success. If a subsequent validation or inode initialization check after mmi_success fails and jumps to out, out1, out2, or out3, the error cleanup at out only calls brelse(bh1) and brelse(bh2) (both NULL), leaking the qs->sb_buf buffer_head reference. Release qs->sb_buf at out when it is distinct from bh1 and bh2 (using qs->sb_buf rather than sbi->sb_buf because sbi is not yet initialized if mmi_success jumps to out on superblock level validation failure). Tested in QEMU against Linux 7.3.0-rc3 by mounting a crafted QNX6 mmi_fs image on /dev/loop0 that succeeds in qnx6_mmi_fill_super() (allocating qs->sb_buf at block 0) and then fails root directory validation, followed by flushing per-CPU bh_lrus and pagecache via /proc/sys/vm/drop_caches and POSIX_FADV_DONTNEED: on the unfixed kernel block 0 remains pinned in bd_mapping by the leaked qs->sb_buf buffer_head (sb_buf_page0_leaked = 1), whereas on the fixed kernel qs->sb_buf is released and evicted cleanly (sb_buf_page0_leaked = 0). Fixes: 5d026c724220 ("fs: initial qnx6fs addition") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng --- Changes in v2: - Split the mmi_fs qs->sb_buf leak fix into its own patch (4/6) separate from the double-brelse fix (3/6), use qs->sb_buf instead of uninitialized sbi->sb_buf, and remove Markdown formatting from the commit message, as requested by Damien Le Moal. fs/qnx6/inode.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/qnx6/inode.c b/fs/qnx6/inode.c index c4a35d81e67c..124b60b47c8e 100644 --- a/fs/qnx6/inode.c +++ b/fs/qnx6/inode.c @@ -467,6 +467,8 @@ static int qnx6_fill_super(struct super_block *s, struct fs_context *fc) out1: iput(sbi->inodes); out: + if (qs->sb_buf && qs->sb_buf != bh1 && qs->sb_buf != bh2) + brelse(qs->sb_buf); brelse(bh1); brelse(bh2); outnobh: -- 2.49.0