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[34.82.187.25]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3a4ce1c9045sm588743a91.12.2026.09.29.20.16.06 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Sep 2026 20:16:06 -0700 (PDT) From: Hui Peng To: Anders Larsen Cc: Matthias Goergens , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Hui Peng Subject: [PATCH v4 1/6] qnx6: validate di_filelevels in qnx6_iget() before accessing level pointers Date: Wed, 30 Sep 2026 03:15:59 +0000 Message-ID: <20260930031604.70544-2-benquike@gmail.com> X-Mailer: git-send-email 2.56.0.rc1.315.gc6ed9934b7-goog In-Reply-To: <20260924073920.2782917-1-benquike@gmail.com> References: <20260924073920.2782917-1-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 In qnx6_iget(), raw_inode->di_filelevels is read from disk without upper bounds checking. If raw_inode->di_filelevels exceeds QNX6_PTR_MAX_LEVELS (defined as 5 in include/linux/qnx6_fs.h), qnx6_block_map() performs out-of-bounds reads past di_block_ptr when dereferencing indirect tree levels. Validate raw_inode->di_filelevels against QNX6_PTR_MAX_LEVELS in qnx6_iget() and return -EIO if it exceeds 5. Tested in QEMU against tip of mainline commit 62f4c998b297 ("Merge tag 'parisc-for-7.3-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux") using a loop-device reproducer mounting a crafted QNX6 image with di_filelevels = 20: on the unfixed kernel, mounting triggered a buffer_head refcount underflow warning ("VFS: brelse: Trying to free free buffer"); whereas with this fix applied, qnx6_iget() cleanly rejects the corrupted inode with -EIO and logs "qnx6: bad filelevels 20 (max 5) on dev loop0, inode 1". Fixes: 5d026c724220 ("fs: initial qnx6fs addition") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Hui Peng --- Changes in v4: - Rebased cleanly onto upstream mainline commit 62f4c998b297. - Added QEMU test procedure and verification details in commit message body. - Updated commit description to state QNX6_PTR_MAX_LEVELS is 5 as noted by Matthias Goergens. fs/qnx6/inode.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/qnx6/inode.c b/fs/qnx6/inode.c index a15bb03f0ec3..e61c33f2e146 100644 --- a/fs/qnx6/inode.c +++ b/fs/qnx6/inode.c @@ -561,6 +561,14 @@ struct inode *qnx6_iget(struct super_block *sb, unsigned ino) sizeof(raw_inode->di_block_ptr)); ei->di_filelevels = raw_inode->di_filelevels; + if (ei->di_filelevels > QNX6_PTR_MAX_LEVELS) { + pr_err("bad filelevels %u (max %u) on dev %s, inode %u\n", + ei->di_filelevels, QNX6_PTR_MAX_LEVELS, sb->s_id, ino); + folio_release_kmap(folio, raw_inode); + iget_failed(inode); + return ERR_PTR(-EIO); + } + if (S_ISREG(inode->i_mode)) { inode->i_fop = &generic_ro_fops; inode->i_mapping->a_ops = &qnx6_aops; -- 2.55.0.1082.g2b9226bbc0-goog