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Thu, 23 Apr 2026 21:59:55 -0700 (PDT) Received: from localhost.localdomain ([2600:8802:c01:ca00:45b2:2071:1eb4:e2ce]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-12c919266f6sm24955876c88.1.2026.04.23.21.59.54 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Thu, 23 Apr 2026 21:59:55 -0700 (PDT) From: Tamil Mathi <9tamilmathi@gmail.com> To: paullawrence@google.com Cc: linux-unionfs@vger.kernel.org, kernel-team@android.com, syzbot+75ff1aecfbeeefb78736@syzkaller.appspotmail.com, Tamil Mathi <9tamilmathi@gmail.com> Subject: [PATCH] incfs: validate rlog_pages mount option against MAX_ORDER_NR_PAGES Date: Thu, 23 Apr 2026 21:59:54 -0700 Message-Id: <20260424045954.3187-1-9tamilmathi@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-unionfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The rlog_pages mount option is parsed from user-supplied mount data and used directly to compute the read log ring buffer size: new_buffer_size = PAGE_SIZE * options->read_log_pages; new_buffer = kzalloc(new_buffer_size, GFP_NOFS); kzalloc() for a contiguous allocation larger than MAX_ORDER_NR_PAGES pages triggers WARN_ON(order > MAX_ORDER) in __alloc_pages_noprof(). A user can pass rlog_pages=22472 (~88 MB) to reliably trigger this WARNING during mount. Fix this by rejecting rlog_pages values that exceed MAX_ORDER_NR_PAGES at parse time, returning -EINVAL for out-of-range values. Reported-by: syzbot+75ff1aecfbeeefb78736@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=75ff1aecfbeeefb78736 Signed-off-by: Tamil Mathi <9tamilmathi@gmail.com> --- fs/incfs/vfs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/incfs/vfs.c b/fs/incfs/vfs.c index b45533b..4eaf890 100644 --- a/fs/incfs/vfs.c +++ b/fs/incfs/vfs.c @@ -270,6 +270,8 @@ static int parse_options(struct mount_options *opts, char *str) case Opt_rlog_pages: if (match_int(&args[0], &value)) return -EINVAL; + if (value < 0 || value > MAX_ORDER_NR_PAGES) + return -EINVAL; opts->read_log_pages = value; break; case Opt_rlog_wakeup_cnt: -- 2.39.5 (Apple Git-154)